ANNUAL REPORTSON THEPROGRESS OF CHEMISTRYGENERAL AND PHYSICAL CHEMISTRY.1. INFRARED AND RAMAN SPECTROSCOPY.THE first part of this Report deals with the spectra of molecules consideredas isolated systems and continues with spectral effects characteristic first ofcondensed phases and then of more specific forms of association, such ashydrogen bonding. Some miscellaneous topics and papers on apparatusand techniques are reported at the end.During the year, Volume IX in the series “ Techniques of OrganicChemistry,” entitled “ Chemical Applications of Spectroscopy,’’ hasappeared. This volume, edited by W. West, contains inter al. chapters onthe theory of infrared and Raman spectroscopy including the application ofgroup theory to molecular vibrations and on the applications of infraredand Raman spectroscopy to the elucidation of molecular structure of organiccompounds.Greater emphasis is given to infrared methods. Complement-ing this treatment, the Raman spectroscopy of inorganic compounds hasbeen reviewed.2 Other reviews have been given on the use of infraredspectroscopy in structural and analytical ~tudies,~ in the study of naturalproduct^,^ and in relation to intramolecular effects (ring strain, conjugation,etc.). A catalogue of infrared spectra of gases has been published andRussian work on the resonance-Raman effect (Raman spectra excited byradiation of frequency close to the resonance frequency of the molecule) hasbeen reviewed.’ Abstracts have been published of papers presented atinternational conferences at Pittsburg Sa on Analytical Chemistry andApplied Spectroscopy and at Ohio 8b on Molecular Structure and Spectro-scopy.Potential Functions.-A new potential function for diatomic moleculeshas been ~uggested,~ applicable to molecules for which data are available1 “ Techniques of Organic Chemistry,” General editor A.Weissburger, Vol. IX,“ Chemical Applications of Spectroscopy,” Interscience Publishers, Inc., New York andLondon, 1956.L. A. Woodward, Quart. Rev., 1956, 10, 185.3 J. Lecomte and Y.-R. Naves, J . Chim. phys., 1956, 53, 462; L. J. Bellamy,A. R. H. Cole, Fortschr. Chem. org. Naturstofle, 1956, 13, 1.R. C. Lord and F. A. Miller, Appl. Spectroscopy, 1956, 10, 115.J. Behringer and J. Brandmiiller, 2. Elektrochem., 1956, 60, 643.(a) Spectrochiwt.Acta, 1966, 8. 107; (b) ibid., p. 280.C. Le R. Beckel, J . Cham. Phys., 1956, 24, 553.Research, 1956, 9, 147 ; A. E. Martin, Ind. Chemist, 1956, 32, 464.6 R. H. Pierson, A. N. Fletcher, and E. St. C. Gantz, Analyt. Chem., 1956, 28, 12188 GENERAL AND PHYSICAL CHEMISTRY.for higher vibrational states. Linnett lo has discussed the internucleardistances and force constants of a number of diatomic molecules in terms ofthe number of electrons in the bonding region and the 0 or x character ofthe electrons. There are still few accurate vibrational data for isotopicallysubstituted molecules other than for deuterium substitution. Such dataare necessary to evaluate the force constants of the most general quadraticpotential-energy function. Thus, for bent XY, molecules, while threefundamental frequencies can be observed there are two primary and twointeraction force constants to be evaluated.Smith and Linnett l1 havediscussed the relation between these when the three frequencies are known,for a number of molecules of this type, and have indicated ways in which,in the absence of isotopic data, one of the force constants can be estimated,so fixing approximately the values of the others. Besides providing morereliable values of the primary constants the interaction constants provideresults of direct chemical interest as they may often be related to electronicchanges in one bond caused by stretching or bending another. Smith andLinnett l1 suggest that the compression of the lone pairs may contributeto the bending constant in such molecules as 0,, NO,-, etc. Simpson l2has pointed out that potential-energy terms linear in angle may occur forthe out-of-plane vibrations of planar molecules and that such terms arelikely to be important where interatomic repulsion is large.Vibration-Rotation Spectra.-Numerous vibration-rotation spectralstudies have been published. Molecules studied include NO l3 (re =1.1506 A), CS, l4 (CS r, 1.553 A), N,O l5 (the four constants in the quadraticpotential-energy expression obtained), HCN and DCN 16- l7 (complete setof vibrational anharmonic constants calcdated),17 0, 18* l9 (with a deter-mination l9 of the four quadratic potential-energy constants from combineduse of infrared data and measurements by microwave spectroscopy ofcentrifugal distortion effects), D,O and HDO 2o (in great detail), H2S 21(re-assignment of strong absorption round 2600 cm.-l to vl), H2Te,22CD,F 23* 24 (compared with that in methane, the C-H bond is lengthenedand the HCH angle enlarged 23) , C10,F 25 (symmetric top), allene,26* 27* 28and deuterated allenes 27* 28 (infrared 26, 28 and Raman 27 studies).lo J.W. Linnett, J., 1956, 276.l 1 S. Smith and J. W. Linnett, Trans. Faruduy SOC., 1956, 52, 891.12 C. J. S. M. Simpson, J . Chem. Phys., 1956, 24, 1109.13 H. W. Thompson and B. A. Green, Spectrochim. Actu, 1956, 8, 129.l4 H. C. Allen, jun. , E. K. Plyler, and L. R. Blaine, J . Amer. Chern. SOC. , 1966, 78,15 E. K. Plyler, E. D. Tidwell, and H.C. Allen, jun., J . Chem. Phys., 1966, 24, 95.113 I. R. Dagg and H. W. Thompson, Trans. Furaday SOL, 1966, 52, 455.l7 H. C. Allen, jun., E. D. Tidwell, and E. K. Plyler, J . Chem. Phys., 1956, 25, 302.18 L. D. Kaplan and L. Neven, ibid., 24, 1183.19 L. Pierce, ibid., p. 139.2O W. S. Benedict, N. Gailar, and E. K. PlyIer, ibid., p. 1139.81 H. C. Allen, jun., L. R. Blaine, and E. K. Plyler, ibid., p. 35.22 K. Rossmann and J. W. Straley, ibid., p. 1276.Z3 F. A. Anderson, B. Bak, and S. Brodersen, ibid., p. 989.24 W. F. Edge11 and L. Parts, J . Amer. Chem. SOC., 1956, 78, 2358.26 R. P. Madden and W. S. Benedict, J . Chem. Phys., 1956, 25, 594.26 K. N. Rao and E. D. Palik, ibid., 1965, 23, 2112.37 B. P. Stoicheff, Canad. J . Phys., 1955, 33, 811.48 J.Overend and H. W. Thompson. Trans. Furaday SOC., 1966, 52, 1295.4843PULLIN : INFRARED AND RAMAN SPECTROSCOPY. 0Vibration Spectra and Force Constants.-Force constants have beenevaluated for series of molecules of the following types : XH, and XD3,29XY, 30 (planar), XY, 31 (pyramidal), XY, 32 (tetrahedral), M(CH3)3,33 andM(CH3)4.34 The solution of the vibration problem of pyramidal moleculesof the type XY(CH,), has been discussed.35 The force constants of BF, andCF, have been compared with those of the other fluorides of the first rowof the Periodic Table.36Increasing attentionis being given to the infrared spectra of inorganic compounds. New orimproved spectra or interpretations of spectra have been reported for thefollowing compounds of the XY, type : AlCl, (and AL&16),37 PI, and ASI,,~~PH,+ 39 (in PH,I), GaC1,- 40 (in aqueous hydrochloric acid solutions ofGaCl, and in fused GaC1,) and BH,- 41 (from these spectra and publisheddata comparison was made of the bond-stretching force constants in thefour series of isoelectronic compounds : BH,- , CH,, NH,+ ; AlH,-, SiH,,PH,' ; AlCl,-, SiCI,, PC14+ ; and ZnCl,2-, GaC14-, GeC1,) ; also for ZIICI,~-and CdC1,2-,42 AlH,- * (in LiAIH,), SF,,@ OSO,,,~ AuC~,-,~~ PF5,4' UF,,,*NpF,, and Among closely related compounds, studies have beenmade of the mixed halides of boron 50 and g e r m a n i ~ m , ~ ~ sulphur di~hloride,~~sulphur and selenium halides of the type S,X,,53 and tetramethyltin.s Ofconsiderable chemical interest is the determination of the infrared absorp-tion spectrum of the N, radical by Pimentel and his co-workers 65 by the'' matrix isolation method " in which the reactive species and a large excessof inert diluent, such as argon, are rapidly condensed on a transparent platemaintained at a low temperature.Also of interest is the report 56 of twoSpectra of inorganic and metallo-organic compounds.a* V. P. Morozov, Zhur. $2. Khim., 1955, 29, 1804.30 K. Venkateswarlu and S. Sundaram, J . Chem. Phys., 1955, 23, 2368.31 Idem, Proc. Phys. Soc., 1956, 69, A , 180.3!4 Idem, J . Chem. Phys., 1955, 23, 2365.33 K. Shimizu, J . Chew. SOC. Japan, 1956, 77, 1103.34 Idem, ibid., p. 1284.3 5 H. C. Beachell, B. Katlafsky, and J. L. Lauer, J . Chem. Phys., 1955, 23, 2171.36 J.Goubeau, W. Bues, and F. Kampmann, 2. anorg. Chem., 1956,283, 123.37 W. Klemperer, J . Chem. Phys., 1956, 24, 353.30 L. A. Woodward and H. L. Roberts, Trans. Faraday SOC., 1956, 52, 1458.40 Idem, J., 1956, 3721, 3723.41 Idem, ibid., p. 1170.42 M. A. Bredig and E. R. Van Artsdalen, J . Chem. Phys., 1956, 24, 478.43 L. D'Or and J. Fuger, Bull. SOC. roy. Sci. LiPge, 1956, 25, 14.R. E. Dodd, L. A, Woodward, and H. L. Roberts, Trans. Faraday SOC., 1956,52,1052.46 L. A. Woodward and H. L. Roberts, ibid., p. 615 ; N. J. Hawkins and W. W. Sabol,46 A. A. Vlkk and P. Beran, Chem. Listy, 1956,50. 1306.4 7 J. P. Pemsler and W. G. Plaget, jun., J . Chem. Phys., 1956, 24, 920.49 Idem, ibid., 1955, 23, 2192; N. J. Hawkins, H. C.Mattraw, and W. W. Sabol,50 L. P. Lindeman and M. K. Wilson, J . Chem. Phys., 1956, 24, 242.51 0. HAlov&, Coll. Czech. Chem. Comm., 1955, 20, 1261.62 C. Otero and J. R. Barcelb, Anales Fis. Quim., 1956, 52, B, 291.63 H. Stammreich and R. Forneris, Spectrochim. Acta, 1956, 8, 46.64 W. F. Edge11 and C. H. Ward, J . Amer. Chem. SOL, 1955, 7'7, 6486.6 6 D. E. Milligan, H. W. Brown, and G. C . Pimentel, J . Chem. Phys.. 1956,245, 1080.66 J. T. Mulhaupt and D. F. Hornig, J . Chem. Phys., 1956, 24, 169.H. Stammreich, R. Forneris, and Y . Tavares, ibid., 25, 580.J . Chem. Phys., 1956, 245, 775.J. G. Malm, B. Weinstock, and H. H. Classen, J . Chem. Phys., 1956, 25, 427.ibid., p. 219110 GENERAL AND PHYSICAL CHEMISTRY.Raman bands in the spectrum of perchloric acid monohydrate which appearto belong to the OH stretching and bending vibration of the hydrosoniumion.Use has been made of infrared emission methods to obtain the spectrumof LiH 57 and of Group I1 halides which show rather unexpected inter-relationships. 58 Metal carbonyls 59 and the interesting compounds, thehydrocarbonyls, 6o for which conflicting structures have been proposed, havereceived attention. Spectral studies have been made of the cyanogenhalides,G1 the isocyanate group,62 trifluoromethyl cyanide,g3 boron cyanide,64alkali cyanides, 65 complex cyanides,66 potassium thi0cyanate,~7 metalammines,6s and nitro- and chl~ro-ammines.~~ Closely related to theammines are the series of mercury-nitrogen compounds investigated byBrodersen and Becher.70 These authors evaluated approximately thestretching force constant of the Hg-N bond and assigned frequencies to thevibrational modes of NH, NH,, and NH, groups. A number of similarstudies of inorganic complex and chelate compounds have been published.That of the complex acetates of uranium and some transuranic elements 71is interesting in that it seems to show that the metal-oxygen stretching forceconstant decreases as the metal-oxygen separation decreases. Otherinorganic compounds investigated include N,OZ2- 72 (trans, planar, fromabsence of coincident frequencies between the infrared and Raman spectra),N0,F 73 (probably planar), various sulphur-nitrogen compounds 74 includingthe ring trimer (NSO,-), analogous to the trimetaphosphate ion, the aqueoussilicate ion,75 di-769 77 penta-, and de~a-borane,~' trimethylb~rane,~~ deuter-5 7 W.Klemperer, J . Chem. Phys., 1955, 23, 2452.5 8 W. Klemperer and L. Lindeman, ibid., 1956, 25, 1066.59 S. L. Shufler, H. W. Sternberg, and R. A. Friedel, J . Amer. Chem. SOC., 1956, 78,2687; F. T. King and E. R. Lippincott, ibid., p. 4192; L. H. Jones, J . Chem. Phys.,1955, 23, 2448.60 W. F. Edgell, C. Magee, and G. Gallup, J . Amer. Chem. SOC., 1956, 78, 4185;F. A. Cotton and G. Wlkinson, Chem. and Ind., 1956, 1305.62 H. Hoyer, Chern. Ber., 1956, 89, 2677.s3 W. F. Edgell and R. M. Potter, J. Chem. Phys., 1956, 24, 80.64 J. Guy and M. Chaigneau, Bull. SOC. chim. France, 1956, 257.66 W. Briigel, G. Daumiller, and 0. Romrnell, Angew.Chem., 1956, 68, 440.66 (a) R. A. Penneman and L. H. Jones, J . Chem. Phys., 1956, 24, 293; (b) L. H.Jones and M. M. Chamberlain, ibid., 25, 365; G. B. Bonino and 0. Salvetti, Atti Accad.naz. Lincei, Rend. Classe Sci. j i s . mat. nut., 1956, 20, 150; M. F. A. Elsayed and R. K.Sheline, -1. Amer. Chem. SOC., 1956,78, 702 : D. M. Sweeney, I. Nakagawa, S. Mizushima,and J. V. Quagliano, ibid., p. 889.6 7 J. R. Saraf, Sci. Light, 1956, 5, 23; L. H. Jones, J . Chem. Phys., 1956, 25, 1069.6s D. B. Powell and N. Sheppard, J., 1956, 3108; D. B. Powell, ibid., 4495; G. M.Barrow, R. H. Krueger, and F. Basolo, J . Inorg. Nuclear Chem., 1956, 2, 340.69 I . R. Beattie and H. J. V. Tyrrell, J . , 1956, 2849; D. G. Hill and A. F. Rosen-berg, J .Chcm. Phys., 1956, 24, 1219; L. H. Jones, ibid., 1955, 23, 2105; R. B. Pent-land, T. J . Lane, and J. V. Quagliano, J . Amer. Chem. SOC., 1956, 78, 887.7O K. Brodersen and H. J . Becher, Chem. Ber., 1956, 89, 1487.71 L. H. Jones, J . Chem. Phys.. 1955, 23, 2105.72 L. Kuhn and E. R. Lippincott, J . Amer. Chem. SOC., 1956, 78, 1820.73 R. E. Dodd, J . A. Rolfe, and L. A. Woodward, Trans. Faraday SOC., 1956,52,145.74 H. J. Hofmann and K. Andress, 2. ar,org. Chem., 1956, 284, 234.7 5 D. Fortnum and J. 0. Edwards, J . Inorg. Nuclear Chem., 1956, 2, 264.76 H. C. Beachell and E. J. Levy, J . Chem. Phys., 1955, 23, 2168; D. A. Brown7 7 P. R. Pondy and H. C. Beachell, J . Chem. Phys., 1956, 25, 238.78 J . E. Stewart, J . Res. Nut. Bur. Stand., 1956, 58, 337.W.0. Freitag and E. R. Nixon, J . Chem. Phys., 1956, 24, 109.and H. C. Longuet-Higgins, J . Inorg. Nuclear Chem., 1955, 1, 352PULLIN : INFRARED AND RAMAN SPECTROSCOPY. 11ated germanes 79 and digermane,80 deuterium-substituted silanes, 61 halogen-substituted silanes,s2 CCl,-SC1,83 NCOSC~,,~~ disiloxane, and [2H,]di~iloxane 85(it is suggested that the Si-0-5 angle is close to 180°, from the absence ofgenuine coincidences between the infrared and Raman spectra).Among the simplerorganic compounds for which detailed assignments are possible, halogen-substituted ethanes, ethylenes, and benzenes continue to receive attention ;papers have appeared on CH3*CC13 and CD3*CCl,, 86 sym-tetrachloro- s7a9and sym-tetrabromo-ethane 87b3 88 (sym-tetrabromoethane will crystallise ineither the trans or the gauche form s7b), 1 : 2-dibromo-2 : 2-difl~oroethane,~~trichloroethylene,w trichlorofluoroeth ~ l e n e , ~ l 1 -chloro- 1 -fluoroet hylenqg2mono ha loge no benzene^,^^ dihalogenoben~enes,~~ and hexafluor~benzene.~~Bellamy and N'illiams 96 discuss relations between the frequencies of halidesof the type CH,X and the corresponding halogen acid HX, and betweenthe halides CH,X and molecules CH,Y, for various groups Y such as -CO,H,-Sic&, -SH, etc.These relations are interpreted largely in terms of changesof hybridisation. Several papers have appeared on the spectra of formicacid and related compounds : formic acid,97 f~rmaldehyde,~~ formate i~n,~ga*formyl fluoride,loo acetate ion, 99b9 lola oxalate ion,l0la8 and osalic acid.101bThe force field for molecules of type X-CH-0 has been discussed.lo2 Othersmall molecules studied include isobutane and [2H1]i~~butane, lo3 proyeneSpectral studies of individual organic compoatnds.79 L.P. Lindeman and M. K. Wilson, 2. phys. Chent. (Frankfurt), 1956, 9, 29.80 D. A. Dows and R. M. Hexter, J . Chern. Phys., 1956, 24, 1029, 1117.8% K. Kawai and H. Murata, ibid., 1955, 23, 2451 ; C. Newnian and J. K. O'Loane,8s F. Feh6r and H. J. Barthold, 2. anorg. Chem., 1956, 284, 60.84 F. FehCr and W. Weber, 2. Naturforsch., 1956, l l b , 426.8S R. C. Lord, D. W. Robinson, and W. C. Schrumb, J . Amer. Chew. Soc., 1956, 78,86 J. C. Evans and H. J. Bernstein, Canad. J . Chern., 1955, 33, 1746.( a ) S. Mizushima and co-workers, J .Chenz. Phys., 1955, 23, 1907; J. P. Zeitlow,F. F. Cleveland, and A. G. Neister, ibid., 1956, 24, 142; (b) K. E. Kagarise, ibid.,J. H. Meal and M. K. Wilson, ibid., p. 385.S. R. Polo, and M. K. Wilson, ibid., 1956, 25, 855; Y . Morino, ibid., 1956, 24, 164.1327.p. 300.88 D. E. Mann, J. H. Meal, and E. K. Z'lyler, ibid., p. 1018.89 R. E. Kagarise, ibid., p. 1264.J. C. Evans and H. J. Bernstein, Canad. J . Chenz., 1955, 33, 1792; T. J. liouser,R. B. Bernstein, R. G. Miekka, and J. C. Angus, J . Amer. Chem. SOC., 1955, 77, 6201.91 D. E. Mann and E. K. Plyler, J . Cltem. Ph-ys., 1955, 23, 1989; J . R. Nielsen,C. W. Gullikson, and A. H. Woolett, ibid., p. 1994.O2 D. E. Mann, N. Acquista, and E. K. Plyler, ibid., p. 2122.Og D.H. Whiffen, J., 1956, 1350; D. 1%'. Scott and co-workers, J . Amer. Chew.SOL., 1956, 78, 5457.A. Narasimham, M. 2. El-Sabban, and J . H. Nielsen, J . Chcm. Phys., 1956, 24,420, 433, 1232; S. L. N. G. Krishnamachari, Current Sci., 1956, 25, 185, 260.95 L. Delbouille, J . Chem. Phys., 1956, 25. 182.g6 L. J. Bellaniy and R. L. Williams, J . , 1956, 2753.87 W. J. Orville-Thomas, Research, 1956, 9, s15; D. Chapman, J . , 1956, 225;9g T. Miyazawa, J . Chem. SOC. Japagz, 1955, 76, 1132.99 K. Ito and H. J. Bernstein, (a) J . Chcm. SOC. Japan, 1956, 77, 381 ; ( b ) Canad.loo H. W. Morgan, P. -4. Staats, and J. H. Goldstein. J . Chem. Phys., 1966, 25, 337.lol (a) K. J. Wilmshurst, ibid., 1955, 23, 2463; (b) H. Murata and K. Kawai, ibid.,lo2 T.Miyazawa, J. Chem. SOC. Japan, 1956, '97, 366.lo9 J. C. Evans and H. J. Bernstein, Canad. J . Chem., 1966, 34, 1037.J. K. Wilmshurst, J . Claem. Phys., 1956, 25, 478.J . Chem., 1956, 34, 170.1966, 25, 58912 GENERAL AND PHYSICAL CHEMISTRY.and deuteropropene ,lO4 cyclohe~ene,~~5 CH,CN, and CD,CN, s6 compoundsrelated to adamantane and urotropinJ106 ethylene oxide,lo7 ozonides ofethylene, propene, and isobutene,los ethylene carbonate log (probably planarin the liquid state), naphthalene,l1° anthracene and tetracene,lll acet-aldehyde,l12 diacetyl,l13 dicyanoacetylene,ll* halogen~picrins,~~~ and somealkyl phosphates and thiophosphates.1l6 It is possible only to refer to asmall fraction of all the organic structures investigated by infrared andRaman spectroscopy : a few of the groups of compounds that have receivedmost attention are referred to below.Characteristic spectra o f g o q 5 s .Ketorces. The carbonyl group continuesto be the subject of numerous spectroscopic investigations. Ha1ford,ll7 in apaper basic to any discussion of variation of the carbonyl stretching fre-quency, investigates the location of the carbonyl frequency in a variety ofmodels applicable to non-conjugated ketones. He shows that in a planarmodel (MC),CO in which the M-C linkage is a normal single bond, thecarbonyl frequency is insensitive to variation of mass or position of M andthat the Y shaped C,CO model can be used with fair accuracy to obtain thecarbonyl force constant. The carbonyl frequency increases linearly withcarbonyl force constant and decreasing C-C-C angle; this is supported byexperimental evidence.Data defining frequency-bond-length correlationsfor CO and CN bonds have been assembled.ll8 Lecomte, Josien, and Las-combe 119 examined a large number of ketones in the KBr region and wereable to trace through the series bands arising from three bending modes.Jones et discuss the origin of some low-frequency bands in steroids.Attention has been drawn to the higher intensity of the Raman spectra andthe lower carbonyl frequency of conjugated ketones compared with thoseof similar uncon j ugated ketones. 121 Shorygin had previously discussed indetail the effect of conjugation on Raman intensities.122 The effects oflo4 L. M. Sverdlov, Doklady Akad.Nauk S.S.S.R., 1956, 106. 80.lo6 K. Sakashita, J . Chem. SOC. Japan, 1956, 77, 1094.lo6 R. Mecke and H. Spiesecke, Chem. Ber., 1955, 88, 1997; Spectrochim. Ada, 1956,7, 387; J . Chem. Phys., 1956, 25, 577; A. Cheutin and J.-P. Mathieu, J. Chim. phys.,1956, 53, 106.lo? R. C. Lord and B. Nolin, J. Chem. Phys., 1956, 24, 656.lo8 D. Garvin and C. Schubert, J. Phys. Chem., 1956, 60, 807.lo9 C . L. Angell, Trans. Faraday SOC., 1956, 52, 1178.110 J. Brandmiiller and E. Schmid, 2. Physik, 1956, 144, 428.111 J. W. Sidman, J. Chem. Phys., 1956, 25, 116, 122.112 J. C. Evans and H. J. Bernstein, Canad. J. Chem., 1956, 34, 1083.113 J. W. Sidman and D. S. McClure, J. Amer. Chem. SOC., 1955, 77, 6471.114 F. A. Miller, R. B. Hannan, jun., and L.R. Cousins, J . Chem. Phys., 1955, 23,115 J. Mason and J . Dunderdale, J . , 1956, 754, 759.1 l 6 M. Baudler, Naturwiss., 1956, 43, 124; J. Michalski, R. Mierzecki, and E.11' J. 0. Halford, J. Chem. Phys., 1956, 24, 830.118 E. M. Layton, jun., R. D. Kross, and V. A. Fassel, ibid., 25, 135.119 J . Lecomte, M.-L. Josien, and J. Lascombe, BulE. SOC. chzm. France, 1956,120 R. N. Jones, B. Nolin, and G. Roberts, J. Amer. Chem. Soc., 1955, 77, 6331.L. Piaux, M. Durand, and L. Henry, Compt. rend., 1956,242, 2650; M. Harrandand H. Martin, Bull. SOC. chim. Fralzce, 1956, 1383.lZ2 P. P. Shorygin, Uspekhi Khim., 1950, 19, 419; English translation, NationalResearch Council of Canada, Technical translation TT-228.2127.Rurarz, Roczniki Chem., 1956, 30, 651.163-165PULLIN INFRARED AND RAMAN SPECTROSCOPY.13conjugation, 123 halogen substitution 124 and transannular interaction lo5(in cyclic ketones) on the carbonyl band have been further investigated.Hydrocarbon and C-H modes. A high proportion of papers on hydro-carbons have been concerned with C-H deformation frequencies.126* 12'9 128* 129Kross, Fassell, and Margoshes have discussed the C-H out-of-planebending frequencies of a large number of mono- and di-substituted benzenes(see also Bellamy 126b and Kakiuti 126c). Groups attracting electrons outof the ring raise the C-H bending frequencies. Kross et aZ.12G" suggest thathigher bending frequencies are to be associated with decreased ability of thex electrons to contribute to sp3 character in the carbon orbitals as thehydrogen atoms move out of the plane.Whiffen127 has shown that thestronger infrared bands in benzene from 1650 to 2000 cm.-l can be interpretedas summation tones of out-of-plane C-H bending modes. The frequenciesof the summation bands agree quite closely with the sum of the fundamentalfrequencies, suggesting low mechanical anharmonicity. Whiflen suggeststhat large electrical anharmonicity is characteristic of out-of-plane bendingmotion of C-H bonds having $2 hybridisation and also of bending motionof C-H bonds having sp hybridisation. The analytical use of the C-Hstretching region has been discussed. 130 Among other groups of compoundsthat have received attention are polynuclear hydrocarbons ll1- 131 andrelated fatty acids,lzo9 133 glycerides,134 glycols,136 ethers,13Ga l k o ~ i d e s , ~ ~ ~ i m i n e ~ , l ~ ~ and compounds containing the nitro-group.lagFurther advance has been made in theinterpretation of the spectra of amides, peptides, and proteins. A thoroughinvestigation of the spectra of a series of A'-monosubstituted amides invarious physical states has been made by Japanese ~ 0 r k e r s . l ~ ~ The spectraldata, together with the results of force-constant calculations, were used toassign to their vibrational modes six bands characteristic of monosubstitutedamides. Other papers have appeared on the doubling of a band near 3p inAmides, $@tides, and proteins.123 S. Inayama, Pharm. Bull. (Japan), 1956, 4, 198.lS4 H. Gerding and H. C. Haring, Rec.Trav. chim., 1955, 74, 1409.125 N. J. Leonard et al., J . Amer. Chem. SOC., 1955, 77, 6234, 6237.126 ( a ) R. D. Kross, V. A. Fassell, and M. Margoshes, J . Amer. Chem. SOC., 1956, 78,1332; ( b ) L. J. Bellamy, J . , 1955, 2818; (c) Y . Kakiuti, J . Chem. Phys., 1956, 25, 777.lP7 D. H. Whiffen, Spectrochim. Actu, 1955, 7, 253.lz8 J. K. Brown and N. Sheppard, Trans. Faraday SOC., 1955, 51, 1611.129 M.-L. Josien and J.-M. Lebas, Bull. SOC. chim. France, 1956, 53, 57, 62.130 D. L. Guertin, S. E. Wiberley, and W. H. Bauer, J . Amer. Oil Chemists' SOC.,131 N. Fuson and M.-L. Josien, J . Amer. Chem. SOC., 1956, 78, 3049.l 3 Z L. Cencelj and D. Hadzi, Spectrochim. Actu, 1955, 7, 274.133 D. L. Guertin, S. E. Wiberley, and W. H. Bauer, Analyt.Chem., 1956, 28, 1194;R. T. O'Connor, J . Amer. Oil Chemists' SOC., 1956, 33, 1 ; 1%'. Fuchs and R. Drieberg,Fette u. Seifen, 1956, 58, 3; R. T. Holman and P. R. Edmondson, Analyt. Chem., 1956,28, 1533.134 D. Chapman, J., 1956, 55, 2522.135 N. Chakhovskoy, R. H. Martin, and (in part) R. Van Nechel, Bull. SOC. chim.belges, 1966, 65, 453.136 G. Lagrange and P. Mastalgi, Compt. rend., 1955, 241, 1947.197 D. L. Guertin et al., J . Phys. Chem., 1956, 60, 1018; F. H. Seubold, jun., J .Org. Chem., 1956, 21, 156.138 J. Fabian, M. Legrand, and P. Poirier, Bull. SOC. chim. France, 1956, 1461, 1499.139 J. F. Brown, J . Amer. Chem. SOC., 1955, 77, 6341.140 T. Miyazawa, T. Shimanouchi, and S. Mizushima, J . Chem. Phys., 1956, 24, 408.1956, 33, 17214 GENERAL AND PHYSIC.11, CHEbIISTR\'.the spectra of some N-monosubstituted amides, which was interpreted asevidence for cis-trans-isomerism : 141 the near-infrared spectrum of thepeptide group,142 the infrared dichroism of acetanilide and the transitionmoment direction of the amide-I charactcristic vibration,143 and the di-chroism of fibrous proteins in the 2p region.144 A summary has been givenof the use of infrared spectroscopy in investigating polypeptide and proteinstructures.145 Blout and Asadourian,146 using infrared methods, examinecritically one case of the supposed a -+ 9 transformation of polypeptidesin the presence of formic acid.Lcnormant 14' has studied by infraredmethods the state of proteins in silk glands and the process by which theybecome insoluble.He suggests that the insolubilisation of the proteins ofsilk glands by mechanical strain corresponds to the same change as thatoccurring in the thermal denaturation of other proteins. Goulden 148 hasused infrared methods to investigate protein-sugar interactions. Severalother papers on proteins and related materials have appeared. 149Compounds of biological interest forwhich infrared spectra have been reported include deoxyribonucleic acid,150vitamin B, and related salts of phosphoglyceric acid,152thymus nucleohi~tone,~~~ adenosine phosphate,lN anhydrous p-lacto~e,l~~charoninsulphuric acid, chrondroitinsulphuric acid, and related poly-saccharides, and halogeno-st eroids .Intensities.-The determination of bond moments and their spatialderivatives from gas-phase infrared intensity measurements has now becomefairly standardised ; however, considerable discretion is usually needed.Abrief critical survey of the position at the end of 1955 has been given byHornig.15* The importance of taking into account movements during thevibration of all thc electrons, especially unshared pairs, is emphasised andillustrated by a consideration of the intensity of v2 (symmetrical bendingmode) of ammonia and the intensity and force constant of the bending modeof hydrogen cyanide. Theoretical calculations 159 indicate that the majorpart of the intensity of the v2 vibration of ammonia is due to the changingSome spectra of bioZogica1 interest.141 R. A. Russell and H. W. Thompzon, Spectvochim.Acta, 1956, 8, 138.142 K. T. Hecht and D. L. Wood, Pruc. Roy. Soc., 1956, A , 235, 174.143 N. B. Abbott and A. Elliott, ibid., 234, 247.144 R. D. B. Fraser, J . Chew. Phys., 1956, 24, 89.146 A. E. Elliott, J . Appl. Chem., 1956, 6, 341.146 E. R. Blout and A. Asadourian, J . Amer. Chew. Sor., 1956, 78, 955.14' H. Lenormant, Trans. Faraday Soc., 1956, 52, 549.148 J. D. S. Goulden, Nature, 1955, 177, 85.149 -4. Elliott and B. R. Malcolm, Trans. Favaday Soc., 1956,52, 528; E. Ellenbogen,J . Amer. Chem. SOC., 1956, 78, 363, 366, 369; H. I?. Schwarz et al., Science, 1956, 123,328.H. Lenormant and C . de Loze, Bull. SOC. chim. France, 1955, 1501, 1504; H. P.Schwarz et al., Science, 1956, 123, 328.H. Hirano, H. Yonemoto, and H.Kamio, J . Pharm. SOC. Japan, 1956, 76, 239.C. de Loze and H. Lenormant, Bull. SOC. chim. France, 1956, 450.K. Nakanishi, N. Takahashi, and F. Egami, Bull. Chem. SOC. Japan, 1956, 29,lS2 A. Rosenberg and B. G. Malmstrom, Acta Chem. Scand., 1955, 9, 1546,lK4 H. Gomahr, W. Miedreich, and A. Reuter, Aqzgew. Chem., 1956, 68, 578.l66 Y. Tsuzuki and N. Mori, J . Chem. SOC. Japan, 1956, 77, 993.lS7 D. H. R. Barton, J. E. Page, and C. W. Shoppee, J . , 1956, 331.l 6 * D. F. Hornig and D. C. McKean, J . Phys. Chem., 1955, 59, 1133.l 6 0 N. V. Cohan and C . -4. Coulson, Trans. Faraday SOC., 1956, 52, 1163.434PULLIN INFKAREI) AND RAMAN SPECTROSCOPY. Idhybridisation of the lone-pair electrons accompanying the motion of theatoms. A more sophisticated and more accurate way of obtaining the trueintensities from the experimental figures has recently been applied to thecarbon dioxide bending vibration.lW The importance of using an adequatepotential function when interpreting infrared intensities is shown by somecalculations of moments for sulphur dioxide.lsl However, a more funda-mental difficulty is revealed by the work of Russell and Thompson 162 whoinvestigated the mechanical and electrical anharmonicity of the N-Hstretching vibration in a series of organic compounds in solution.Theyfound a large variation in the relative intensity R of first overtone to funda-mental, due almost entirely to variation in the intensity of the fundamental.In some cases (dimethylamine and diethylamine) the first overtone wasmore intense. The high values of R were due to high electrical, rather thanhigh mechanical, anharmonicity.From the data given the mechanicalanharmonicity factor x, can be seen to increase slightly with increasing R.Investigations of variation of intensity and frequency of characteristicvibrations of groups, as a function of other substituents in the molecule,continue ; exceptionally large variations of intensity of the CGN stretchingvibration have been found.lGd The intensity of the carbonyl stretchingvibration in cyclic ketones shows an interesting variation with ring s i ~ e . 1 ~ Experimental 165 and theoretical intensity work on paraffins has beenreported. The bond moment and the first and the second derivative of thebond moment were obtained for hydrogen chloride from infrared dispersionmeasurements by E e g a ~ .l ~ ~ Raman intensities have been calculated semi-quantitatively for C,H,X (X = C1, Br, and I) by using the approximationof x electrons in a one-dimensional box with infinite walls.168 Apparatusand methods for determining Raman intensities have been described 169and some depolarisation ratios for CC1,X- and CBr,X-type moleculesca1c~lated.l~~ Raman intensity sum rules have been used as an aid tovibrational assignment. 86Rotational Isomerism.-Rotational isomerism in subs ti tut ed et hanescontinues to receive a t t e n t i ~ n . ~ ~ - ~ ~ Barriers to rotation have been estimatedfor digermane,80 dirnethylaminodib~rane,~~~ CC1,*SC1,83 and diphenylderivatives.172 Internal rotation in polyethylene and its derivatives 173I 6 O L.D. Kaplan and D. F. Eggers, J . Chem. PAYS., 1956, 25, 576.161 D. F. Eggers, 1. C. Hisatsune, and I. Van AIten, J . Phys. Chenz., 1955, 59, 1124.163 H. W. Thompson and G . Steel, Trans. Furaday Soc., 1956, 52, 1451.164 T. Biirer and H. H. Grunthard, Helv. Chzm. Acta, 1956, 39, 356.16s H. Luther and G. Czerwony, 2. phys. Chew. (Frunhfurt), 1956, 6, 286.1 6 6 H. Primas and H. H. Grunthard, Helv. Chim. Ada, 1956, 39, 1182.167 Compt. rend.. 1956, 242, 1593.188 M. V. Vol’kenshtein and S. M. Yazyka, Doklady Akad. Nawk S.S.S.R., 1955, 104,I). A. Long, I>. C. Milner, and A. G. Thomas, Proc. Roy. SOC., 1956, A , 237, 186,A. IVeber and S. M. Ferigle, J . Chem. Ph-w., 1955, 23, 2207; R.H. Krupp,1 7 1 J . E. Stewart, ibid., 1955, 23, 2204.I73 G. Kortiim and H. Maier, 2. fihys. Chem. (Frankfurt), 1956, 7, 207.173 I. J. Novak, Zhur. tekh. Fiz., 1955, 25, 1854; I. M. Ward, Chenz. and Ind., 1956,R. A. Russell and H. W. Thompson, Proc. Roy. Soc., 1956, A , 234, 318.834.197.’3. M. Ferigle, and A. Weber, abid., 1956, 24, 355.90516 GENERAL AND PHYSICAL CHEMISTRY.has been discussed. Calculations made of barriers to internal rotation 174illustrate two quite different approaches to the problem : that the problemis complex is shown by the evidence for the preponderance of attractiveover repulsive forces in some cases of rotational isomerism involving therelative orientation of halide to methyl groups 175 and chloride to carbonylgroups.176 Probably of importance for the investigation of rotationalisomerism are some observations by Orr 177 who examined various trans-stilbene derivatives.The width of the band due to the out-of-plane in-phasevibration of the olefinic hydrogen atoms was greater in derivatives wherethe steric hindrance was greater. The width of this band was supposed tobe due to the short life-time of the vibrational state, which in turn resultedfrom transfer of vibrational energy from this mode to other deformationalmodes.Spectra of Condensed Phases.-The infrared and Raman spectra nowreported are those which show points of interest by virtue of the material’sbeing in a condensed phase. Special effects in gases at high pressures arealso included.Crystals.Several papers on general aspects of crystal spectra haveappeared.178 In a further paper in the series “ Motions of Molecules inCondensed Systems ” Zwerdling and Halford 179 report an investigation ofthe polarisation properties of infrared absorption bands of molecular modesinactive in the free molecule, but active in the crystal because of the lower-ing of the symmetry of the molecule by the crystalline field. The samplestudied was a single crystal of benzene. Polarised infrared studies havebeen made of a large number of salt hydrates and inorganic hydroxyliccompounds 180 and of benzophenone,181 a ~ e t a n i l i d e , ~ ~ ~ KAg(CN),,ls2 andiodoform.ls3 In the study of iodoform, Hexter and Cheung investigated,inter al., the polarisation of the absorption band due to the C-H stretchingmode and found it significantly different from that predicted by the oriented-gas model, that is, the model in which the solid is regarded as a non-interact-ing collection of molecules held rigidly in appropriate relative orientations.This difference was attributed to the effect of combination of the C-Hstretching mode with lattice frequencies.In a further paper, Hexter andDows ls4 consider the effect of libration of the molecular units in the latticeon the polarisation of the infrared absorption bands : with reasonable valuesfor libration frequencies, features of a number of published crystal spectra174 E. A. Mason and M. M. Kreevoy, J . Amer. Chem. Soc., 1955, 77, 5808; B. Bak,175 G.J. Szasz, ibid., 1955, 23, 2449.176 L. J. Bellamy, L. C. Thomas, and R. L. Williams, J.. 1956, 3704.177 S. F. D. Om, Spectrochim. Ada, 1956, 8, 218.l 7 3 (a) C. Haas, ibid., p. 19; (b) H. Poulet, Ann. Phys., 1955, 10, 908.17n S. Zwerdling and R. S. Halford, J . Chem. Phys., 1955, 23, 2221.180 (a) M. Haas and G. B. B. M. Sutherland, Proc. Roy. Soc., 1956, A , 236, 427;( b ) R. E. Rundle, K. Nakamoto, and J. W. Richardson, J . Chem. Phys., 1955, 23, 2460;(t) A.-M. Vergnoux, Compt. rend., 1956, 242, 758; M.-P. Bernard, ibid., p. 1012; H. E.Petch, N. Sheppard, and H. D. Megaw, Acta Cryst., 1956, 9, 29.J . Chem. Phys., 1956, 24, 918.lB1 L. Delbouille, Bull. Classe Sci., Acad. ray. Belg., 1956, 63, 388.lB2 L. H. Jones, J. Chem. Phys., 1956, 25, 379.lB3 R.M. Hexter and H. Cheung, ibid., 1956, 24, 1186.lE4 R. 1%. Hexter and D. A. Dows, ibid., 25, 504PULLIN : INFRARED AND RAMAN SPECTROSCOPY. 17can be accounted for. The most complete study of the infrared spectra ofhydrates was that of gypsum by Haas and Sutherland.l* Reflectionmethods were mainly used to obtain the polarised spectra : the superiorityof reflection over transmission methods for highly absorbing crystals isevident from the results obtained. The coupling of the internal motions ofthe equivalent molecular units (H20 and SO,2-) in the unit cell producedsurprisingly large splittings of frequencies in some cases. The polarisationand relative intensities of bands corresponding to the symmetric and anti-symmetric stretching modes of the H,O units showed interesting anomalies.The polarisation behaviour of v, (the symmetrical bending mode) was foundto agree fairly well with that predicted. In several papers attention isdrawn to the relative constancy in frequency of v2 in different hydrates.lS5The polarisation behaviour of v2 of water has been used as evidence fordeviation from planarity in the system CU-O’~ in CuC&,2H20.Thissuggests some covalent character in the Cu-0 bond.lM Raman spectrahave been reported for gypsum lS6 and several other salt hydrates,ls7hydroxonium salts,188 strontianite,lsg magnesite,lS0 and iodoform.191 Adetailed Raman investigation of single crystals of a- and p-resorcinol byPenot and Mathieu lg2 illustrates the complexity of a detailed analysis ofcrystal spectra and the high standard of experimental work required.Thereported observation of discrete lines in the Raman spectrum of MgO 1g3 has abearing on the theory of crystal spectra. A very detailed discussion of anom-alous effects in the Raman spectra of crystals has been given by Poulet.l7&Compressed gases. A brief review of collision-complex spectra in com-pressed gases and liquids has been given by Ketelaar lg4 (see also ref. 195).Solutions and pure liquids. The intensity of a band of a substance in theliquid phase will differ in general from the gas-phase value, the differencebeing related to the different dielectric constants of the two phases. Thiseffect has been further examined, theoretically for pure liquids l96 andexperimentally for solutions.lS7 It appears that the dielectric theorydeveloped so far for this change of intensity applies strictly only to pureliquids whilst most measurements have been made on solutions. Effectsof molecular interaction on Raman intensities have been examined.lg8\H186 P. J. Lucchesi and W. A. Glasson, J . Amer. Chem. Soc., 1956, 78, 1347; E.186 A. I. Stekhanov, Doklady Akad. Nauk S.S.S.R., 1956, 106, 433.187 A. Weill-Marchand, Compt. rend., 1955, 241, 1456; 1956, 242, 93, 1791.188 D. J. Millen and E. G. Vaal, J., 1956, 2913.189 T. S. Krishnan, Proc. Indian Acad. Sci., 1956, 44, A , 96.lQo D. Krishnamurti, ibid., 43, A , 210.l91 H. Stammreich and R. Forneris, Spectrochim. Ada, 1956, 8, 62.lS2 D. Penot and J.-P.Mathieu, J . Chim. fihys., 1955, 52, 829.lg4 J. A. A. Ketelaar, Rec. Trav. chim., 1956, 75, 857.195 L. Galatry and B. Vodar, Compt. rend., 1956, 242, 1871; A. Michels and H. Delg6 S. R. Polo and M. K. Wilson, J . Chem. Phys., 1955, 23, 2376.197 J. H. Jaffe and S. Kimel, J . Chem. Phys., 1956, 25, 374.lg8 Ya. S. Bobovich et al., Doklady Akad. Nauk S.S.S.R., 1956, 108, 607; Idem,Hartert, Naturwiss., 1956, 43, 275.S. J. KhambMA, Proc. Phys. Soc., 1950, 89. A , 426.Kluiver, Physica, 1956, 22, 919.Zhur. eksp. teoret. Fiz., 1956, 30, 189Evidence for a temperature variation of infrared band intensities has beenput Further, rigorous experimental work is required. Soluteband-widths in mixed solvents have been interpreted in simple statisticalterms.200 Evans and Bernstein 201 measured the polarisation and intensitiesof the two Raman forbidden fundamentals of carbon disulphide in a seriesof cyclopentane solutions.They suggest that interaction between the CS,molecules in solution reduces their symmetry to C, (single plane of symmetryonly). A Raman line suggestive of internzolecztlar vibration has beenobserved with liquid carbon disulphide at - 100°.202 Lafont 203 describesthe Ranian spectrum of a saturated solution of zinc sulphate. The closesimilarity to the complex Raman spectrum of crystalline ZnS0,,7H20 withwhich the solution is in equilibrium, is impressive evidence for regions ofshort-range order in the saturated solution. Solvent effects on characteristicbands of the following groups have been investigated : >C0,Lo2a* -OH,204b>NH,205 -CN,fo6* 163 -NO,, and -CF,.206 Particularly large changes ofintensity with solvent are shown by the -CN group, which are interpretedin terms of changes in the electronic structure of the group.Further papers on interactionin solution are on hydrogen sulphide solutions 207 (including evidence foran H,S-mesitylene complex), sulphur dioxide solutions 208 (includingevidence for an SO,-pyridine complex), association of aldehydes,209 theconcentration-dependent structure of the Raman carbonyl stretching bandin solutions of ketones,2aa complexes between ether and HCl or HRr,210organic complexes with HBr or HI 211 and with aluminium bromide andstaiinic and between benzene and chlorine and bromine 213 (seehowever Murakami 214), Ionic equilibria studied include equilibria in-volving N02+,215 equilibria in molten salts,40* 42 and an outstanding investig-ation of the equilibrium of complex cyanides in aqueous solution.s6aThere is still diversity of opinion about the natureof hydrogen-bonded systems and of their spectral manifestations.Thewidth of OH stretching frequencies in strongly hydrogen-bonded systemshas received much attention in the past, Frisch and Vidale 216 have solvedAssociatiopz and dissociation in solution.Hydrogen bonding.lsB T. 1,. Brown, J . Chem. Phys., 1956, 24, 1281 ; U. Liddel and E . 0. Becker, ibid.,2oo T. Yoshino, ibid., 1956, 24, 76.201 J. C. Evans and H. J. Bernstein, Canad. J . Chem., 1956, 34, 1127.202 S.C, Sirkar and G. S. Kastha, J . Chem. Phys., 1955, 23, 2439.2os R. Lafont, Compt. rend., 1956, 242, 1154.204 ( a ) C. Mangin and M.-M. Bottreau, Compt. rend., 1956, 242, 2637; ( b ) H . Tsubo-205 1'. Mirone and G. F. Fabbri, Gazzetta, 1956, 86, 1079.2O6 E. Lippert and W. Vogel, 2. phys. Chem. (Frankfurt), 1956, 9, 133.207 M.-L. Josien and P. Saumagne, Bull. SOC. chim. France, 1956, 937.208 A. Tramer, Bull. Acad. polon. Sci., CE. 111, 1956, 4, 355.209 W. Suetaka. Gazzetta, 1956, 88, 783.210 G. L. Vidale and R. C. Taylor, J. Amer. Chem. SOC., 1956, 78, 294.311 M.-L. Josien, G. Sourisseau, and U. Castinel, Bull. SOC. chim. France, 1955, 1539.21* V. N. Filimonov and A. N. Terenin, Doklady Akad. Nauk S.S.S.R., 1966, 109.31s E. E. Ferguson, J .Chem. Phys., 1956, 25, 576.214 H. Murakami, ibid., 1955, 23, 1957.216 S. FCnCant and J. Chedin, Cowzpt. rend., 1956, 243, 41.z16 H. L. Frisch and G. L. Vidale, J . Chem. P h p . , 1966, 25, 982.25, 173.mura, J . Chem. SOC., Japan, 1956, 77, 962.799E'ULLIN INFKAKEI) .\NI) KhM;\N SPECTROSCOPY. 19the classical vibration problem of the niodel system X-H * - .Y in which theH Y bond is anharmonic, and show that on these grounds alone consider-able width is to be expected. Barrow217 and Tsubomura218 measurethe intensities of the hydrogen-bonded X-H stretching frequencies(X-H = alcohol or phenol, Y various). The intensities are greater, thegreater the acidity of XH. Barrow derives the high intensity of thisvibration from the increase of ionic character of the X-H bond on extensionand Tsubomura from the transfer of charge (electrons) from Y to X onextension of X-H.Tsubomura points out that the relatively low intensityfound in chelate compounds such as salicylaldehyde can be understood onthe latter basis, as the dipolarity resulting from the above type of chargetransfer can be (formally) eliminated by rearrangement of bonds round theconjugated system. ,4 different explanation seems to be required for theapparent absence of the OH stretching band in the anion of o-hydroxy-benzoic acid.219 Deductions about the nature of hydrogen bonds have beenmade from the observed expansion of crystals containing short hydrogenbonds when the bonding hydrogen is substituted by deuterium. Pirenne 220presents calculations to show that this may be explained without introducingstrongly anharmonic forces or protonic resonance effects if a three-dimensionalmodel of the hydrogen bond is used.Other papers on the nature of thehydrogen bond have appeared.221 Correlations have been suggested be-tween X-H stretching frequencies and X-Y distances for several systems 222and for metallic hydroxides.223 Similar correlations have tentatively beensuggested for the deformation frequencies.22o Sutherland z2* reports on thedeformation frequencies of alcohols. Four bands characteristic of associatedalcohols are found in the region 1450-650 cm.-l. Among specific hydrogenboiiding systems studied were hydrogen bonding by phenols 2 2 5 9 217* 218 andby the thiol g r ~ ~ p .~ ~ ~ ~ ~ ~ ~ ~ It has been noted227 that the spectroscopicevidence does not support C-H * * 0 hydrogen bonding in certain caseswhere molecular interaction is present.Fundamental papers on the normal modes and spectra ofhigh polymers have appeared.228 Spectral changes of polymers consequentPolymers.p17 G. M. Barrow, J . Phys. Chem., 1955, 59, 1129.zl* H. Tsubomura, J . Chem. Phys., 1956, 24, 927.Z19 H. Musso, Chem. Ber., 1955, 88, 1915.220 J. Pirrenne, Physica, 1955, 21, 971.221 V. Von Keussler and G. Rossniy, 2. Elektrochenr., 1956, 60, 136; D. N. Shigorinet ai., Doklady Akad. Nauk S.S.S.R., 1956, 108, 672 ; D. N. Shigorin and N. S.Dokunikhin, Zur. $2. Khim. 1955,29, 1958.p22 N. Nakamoto, M. Margoshes, and R. E. Rundle, J .Amer. Chem. Soc., 1955, 77,6480; G. C. Pimentel and C. H. Sederholm, J . Chem. Phys., 1956, 24, 639.223 0. Glemser and E. Hartert, 2. anoi'g. Cham., 1956, 283, 111.224 G. B. B. M. Sutherland and co-workers, J . Chem. Phys., 1956, 24, 559; 25,778.225 (a) A. Wagner, H. J. Becher, and K.-G. Kottenhahn, Chem. Ber., 1956, 89,1708; ( b ) Y . Sat0 and S. Nakakura, Sci. Light, 1955,4, 120; R. Mecke and G. Rossmy,Z. Elektrochem., 1955, 59, 866.226 A. Menefee, D. A. Aliord, and C . B. Scott, J . Chem. Phys.. 1956, 25, 370.227 W. G. Schneider and H. J. Bernstein, Trans. Faraday SOC., 1956, 52, 13; C.Fauconnier and M. Harrand, Ann. Phys., 1956, 1, 5.228 C. Y. Liang, S. Krimm, and G. B. B. M. Sutherland, J . Chem. Phys., 1956,25, 543; MI. C . Tobin and M.J . Carrano, zbid., p. 1045; E. E. Ferguson, zhid., 24.111520 GENERAL AND PHYSICAL CHEMISTRY.on softening 229 and on irradiation 230 have been described. The effect ofcrystallinity on the infrared spectrum of poly(chlorotrifluoroethy1ene) hasbeen in~estigated.~~lMisceZEaneous applications. A number of papers have appeared on thespectra of adsorbed molecules. These are reported elsewhere in this volume.Infrared spectroscopy has been used to study flames.232 The infraredspectra of glasses,233 clays,234 and coals 235 have been described.Apparatus and Techniques-Evaluations of designs of infrared spectro-photometers have been made,236 and descriptions have appeared of a zir-conium arc source,237 a simple novel slit mechanism,238 a variable-pathabsorption cell for corrosive an apparatus for producing singlecrystals by sublimation,240 an automatic band integrator,241 and Ramanexcitation sources suitable for use with coloured corn pound^.^^^ 242 Otherpapers deal with the matrix isolation method for reactive molecules,243 infra-red measurements out to 140 microns,244 and a method of casting plasticreplica mirrors.245A.D. E. P.2. KINETICS OF CHEMICAL CHANGE.Kinetics in the Gas Phase.-During 1956 the study of chemical reactionsin the gas phase has yielded its usual heavy crop of publications. Thesecan be grouped mainly into a number of well-marked fields-purelytheoretical investigations, experimental studies of molecular decompositionsand isomerisations, reactions between molecules, and reactions involvingfree radicals and atoms.We have omitted here the extensive and ratherspecialised field of combustions, flames, ignitions, and explosions.229 G. S. Markova, G. K. Sadovskaya, and V. A. Kargin, Zhur. fiz. Khim., 1956, 30,437, English summary suppl- No. 2, 9 ; K. A. Fischer and G. Brandes, Naturwiss., 1956,43, 223.230 R. Kaiser, Kolloid Z . , 1956, 148, 168; A. Brockes and R. Kaiser, Naturwiss.,1956, 43, 53.231 I. I. Novak, Zhur. tekh. Fiz., 1955, 25, 1854.232 J . T. Neu, J. Phys. Chem., 1956, 60, 320; T. M. Cawthon and J. D. McKinley,jun., J . Chem. Phys., 1956, 25, 585.233 Ya. S. Bobovich, 0. P. Girin, and T. P. Tulub, Doklady Akad. Nauk S.S.S.R.,1955, 105, 61.234 S. G. GarciB, H. Beutelspacher, and W.Flaig, Anales Fis. QuZm., 1956, 52, B,39, 369; A. Hidalgo and J . M. Serratosa, ibid., p. 101.236 I. G. C. Dryden, Brennstoff-Chem., 1956, 37, 42 ; R. A. Friedel and J . A. Queiser,Analyt. Chem., 1956, 28, 22; G. A. Monnot and A. Ladam, Compt. rend., 1955, 241,1939; K. Kozima, K. Sakashita, and T. Yoshino, J. Chem. SOC. Japan, Ind. Chem.Sect., 1956, 77, 1432.z36 M. J . E. Golay, J. Opt. SOC. Amer., 1956, 46, 422; W. Zehden, S. African Ind.Chemist, 1956, 10, 77; K. Kudo, Sci. Light, 1955, 4, 105; 1956, 5, 1.237 W. H. Cloud, J. Opt. SOC. Amer., 1956, 46, 895.s38 H. M. Crosswhite and W. G. Fastie, ibid., p. 110.239 R. M. Adams and J . J . Katz, ibid., p. 895.240 S. Z. Zwerdling and R. S. Halford, J. Chem. Phys., 1956, 28, 2215.241 F. B. Strauss, Chem.and Ind., 1956, 1140.242 F. T. King and E. R. Lippincott, J . Opt. SOC. Amer., 1956, 46, 661.243 E. D. Becker and G. C. Pimentel, J. Chean. Phys., 1956, 25, 224.244 E. K. Plyler and N. Acquista, J . Res. Nut. Bur. Stand., 1956, 56, 149; C. Y .Liang, S. Krimm, and G. B. B. M. Sutherland, J. Chem. Phys., 1956, 25, 542.245 G. Haas, J . Opt. SOC. Amer., 1955, 45, 945KINETICS OF CHEMICAL CHANGE. 21Theoretical. There have been no entirely new developments in thetheories of rate processes. A few papers extending and clarifying certainaspects of existing theories have appeared ; the remainder are concernedwith the application and testing of established theories. A number ofpapers have been published on mathematical methods of handling certaintypes of mechanism and on the analysis of experimental results.In thefield of unimolecular reactions, Slater has re-emphasised the need for asynthesis of the four main treatments of such reaction processes. He hasmade a contribution in this direction by discussing the r81e of specific disso-ciation probabilities (S.D.P.) in these theories. The “ S.D.P.” is defined asthe probability per second of dissociation of isolated molecules in a givenstate; the state, in the simplest instance, is prescribed solely by a giventotal energy. Slater has shown that m y classical theory based on harmonicvibrations yielding an expression for the high-pressure rate constant of theform k , = A exp (--BIT) has necessarily an S.D.P. identical in form withthat of Kassel’s and must show a pressure dependence of the rate constantidentical with Kassel’s.A similar result is derived for the case correspond-ing to Kassel’s quantum-mechanical treatment. It is pointed out that amore detailed definition of S.D.P., i.e., one in which configuration and theinternal distribution of energy are important, is respoJisible for the fact thatSlater’s theory gives a pressure dependence of the rate constant differentfrom that of Kassel’s theory. Slater concludes that, whereas the conceptof a detailed S.D.P. is inappropriate to Kassel’s theory, it is implicit inEyring’s theory as formulated by Giddings and E ~ r i n g . ~ Slater has de-veloped a quantum-mechanical form of his harmonic-oscillator theory andhas also shown that the effect of anhannonicity on the results of his classicaltheory is negligible.Later, he has treated unimolecular dissociations onthe basis that the activated states are so closely specified that the lifetimeto dissociation is determinate. This “ determinate ” or “ regular ” situationgives different results for the pressure dependence of the rate constant fromthose of his treatment based on the usual assumption that dissociationsoccur at random. He concludes that the “ regular ’’ and “ random ” casesindicate the extremes between which lies the true pressure dependence.The limiting first- and second-order rates, however, are independent of thetype of distribution.The high frequency factors (-10l6 sec.-l) shown by certain moleculardecompositions (see Table 1) have received some attention.has discussed the results for a number of mercury alkyls.Assuming that,in some cases, more than one internal vibrational degree of freedom (up toa maximum of five) can contribute to the activation energy, and usingplausible critical energy values, Pritchard is able to account for the observedfrequency factors and activation energies. This theory has also beenPritchardN. B. Slater, Proc. Leeds Phil. SOC., 1955, 8, 259.Idem, Phil. Trans., 1953, A , 246, 57.J. C. Giddings and H. Eyring, J . Chern. Phys., 1954, 22, 638.N. B. Slater, Proc. Roy. SOC. Edinburgh, 1955, A , 64, 161.Idem, Proc. Leeds Phil. SOC., 1955, 6, 268.Idem, J . Chem. Phys., 1966, 24, 1256.H. 0. Pritchard, J . Chem. Phys., 1956, 25, 26722 GENERAL AND PHYSICAL CHEMISTRY.applied to the thermal decomposition of ketones, a number of which alsoshow high frequency factors (Table 1).The high frequency factors foundfor certain mercury alkyls have also been discussed by Carter, Chappell,and Warhurst in terms of the shape of the potential-energy surface repre-senting the energies of molecular configurations. Both these treatmentsassociate the high frequency factors with decomposition into three fragmentsin a single step, whereas normal ” values, i.e., 1013-1014 sec.-l areassociated with decomposition into two fragments.The ‘ I automatic fundamental calculations of molecular structure ” ofBoys et aL1* are perhaps the most significant theoretical development ofthe past year. Their calculations of the activation energy of the reactionH + H, + H, + H and of the dimensions and vibration frequencies ofthe transition state are the first to be carried out by a direct method withno semi-empirical features. It is claimed that their value for the activationenergy (0-025 atomic unit = 15-6 kcal.mole-l) could be improved withoutan unduly large amount of labour ; further results of this type of work willbe awaited with great interest. Sat0 l1 ha? applied his new semi-empiricalmethod l2 for calculating activation energies to the reactions H + HX +H, + X (X = halogen) and to the energies of X, “ molecules.” The resultsare in closer agreement with experimental values than those of Eyring andhis collaborators and the potential-energy surfaces are free from hollowsnear the saddles.The pre-exponential factors of twelve bimolecular reactions have beencalculated l3 on the basis of simple collision theory and also by using thetransition-state expressions (a) in the partition function form and (b) inthe thermodynamic form, for which the entropies of the activated complexeshave been estimated from analogies with hydrocarbons.Comparing theresults with the experimental values, the authors conclude that method (a)gives results which are a good deal more satisfactory, and method (b) slightlymore satisfactory, than those derived from collision theory. Knox andTrotman-Dickenson l4 have compared the experimental values for therelative pre-exponential factors of pairs of HR molecules in the chlorineatom reactions C1 + HR + CIH + R with the corresponding relativevalues calculated by transition-state theory.These authors consider thatboth the experimental and calculated ratios can be estimated much moreaccurately than absolute values for any one reaction. They are of theopinion that some of the discrepancies between the calculated and observedratios are definitely outside the likely errors in the estimations and may bedue to transmission-coefficient effects. Calculations of the steric factors forthe reactions of hydrogen atoms and radicals with unsaturated moleculeshave been reported.l5. l6D. Clarke and H. 0. Pritchard, J., 1956, 2136.9 H. V. Carter, E. I. Chappell, and E. Warhurst, J., 1956, 106.lo S.F. Boys, G. B. Cook, C. M. Reeves, and I. Shavitt, Nature, 1956, 178, 1207.l1 S. Sato, J . Chem. Phys., 1955, 23, 2465.l a Idem, ibid., p. 592.l3 D. R. Herschbach, H. S. Johnston, K. S. Pitzer,and R. E. Powell, ibid., 1956,25,736.l4 J. H. Knox and A. F. Trotman-Dickenson, J. Phys. Chem., 1956, 60, 1367.lb A. D. Stepukhovich, Doklady Akad. Nauk S.S.S.R., 1953, 92, 127.l6 A. D. Stepukhovich and E. I. Etingof, Z h u r . j z . Khim., 1955, 29, 1974KINETICS OF CHEMICAL CHANGE. 23Further work on the mathematical analysis of chain reaction hasappeared. Blanquet 17 has discussed special cases of chain-branchingmechanisms and Vasil'ev l8 has discussed the integration of the equationsof chain reactions in which the concentrations of active intermediates changewith time.For complex reaction mechanisms, instead of making approxim-ations to the rigorous rate expression so that these may be solved exactly,TABLE 1. A rrhenias parameters of molecular decompositions.Molecule Method (kcal . mole-') (sec .-l) Ref.E ADiethylmercury .............................. F, T 42.5 2 1 x 1014 9Phenylmercury chloride .................... 59 f 3 1 x 1013 ,,Phenylmercury bromide .................... 63 2 2 x 1014 ,,Trifluoroacetone ................................ 67.8 3.0 x 1013Acetophenone ................................... 77.6 11Trifluoroacetophenone ....................... 73.8 1.8 x 10'5 ,,Dibenzfrl ketone ................................ 71.8 1.8 x 1017 ,,72.0 2.4 x 1014 2ii1 -Ni tropropane ................................47.7 2.5 x 1013 ,,2-Nitropropane .............................. 39.0 1 x 1013Diethyl ketone .............................. S,'i(NO) 59.6 3.68 x 1013 IbcycloPenty1 bromide ........................ S 41.4 7.9 x 10'1 33Ethyl nitrate ................................. S 38.0 5.5 x 1014 34Diphen ylmercury ............................. 68 f 4 1 x lOl6 ,,Hexafluoroazomethane ....................... 48.5 9.0 x 1013 85.1 x 10"Benzophenone ................................... 87-5 1-6 x 10" ,,Acetone ......................................... 70.9 1.4 x lo'&NitFoethane .................................... F,"N, 41.4 + 1-1 2.2 x loll 29.......................................Methyl n-propyl ketone ..................... S, I (P) 56.3 1.07 x 1013 31cis- and trans- 1 : 2-Dichloroethylene.. ....S. C 52-7 3.6 x lo1* 32* F, flow system ; S , static system ; T, excess of toluene present ; K2] nitrogen ascarrier gas; I(NO), fully inhibited by nitric oxide; I(€'), inhibited by propene; C,chain reaction suppressed.Morrow l9 has suggested that it is useful to derive an approximate solutionof the rigorous expression by expanding the time variable as a function ofthe concentrations in the form of a Taylor's series. This can avoidintegrations which may be laborious. Papers on the mathematics ofseveral types of consecutive reaction 20i 21, 22* 23 have appeared in one ofwhich 23 the advantages of using matrices are illustrated. A special type ofmechanism involving simultaneous reactions has been discussed.24 Flynn 25has described a method for obtaining the rate constant and order of areaction when the reactant concentrations are unknown and the only availableexperimental information is the rate of formation of an unreactive product.The effect of the products on rates of energy transfer in unimolecular re-actions in the pressure region where the observed rate is determined by thel7 I-'.Blanquet, J. Chim. phys., 1955, 52, 826.S. S. Vasil'ev, Voprosy Khiwz. Kinetiki, Katalizai Keaksionnoi Sposobnosti Akad.J. C. Morrow, J. Chem. Phys., 1955, 23, 2452.Nauk S.S.S.R., 1955, 137.2o M. Talat-Erben, ibid., p. 2445.21 S. Wideqvist, Arkiv Kemi, 1956, 8, 545.22 D. H. McDaniel and C. 13. Smoot, J. Phys. Chem.. 1956, 60, 966.23 A.E. R. Westman and D. B. DeLury, Canad. J. Chem., 1956, 34, 1134.2*1 R. Zahradnik and 0. Schmidt, Chem. Listy, 1956, 50, 180.25 J. H. Flynn, J. Pkys. Chem., 1956, 60, 133224 GENERAL AND PHYSICAL CHEMISTRY.rate of activation has been discussed by Volpe and Johnston.2s They haveapplied their treatment to their recent experimental work27 on the uni-molecular decomposition of nitryl chloride in the presence of various foreigngases at low pressures. In this case, neglect of the energy-transfer efficiencyof the products introduces only small errors in the values of the rate constant.Molecular decompositions. Table 1 gives the values of the activationenergies and frequency factors obtained by new investigations on molecularthermal decompositions.All the examples have been shown to be first-order reactions (at least in the initial stages) and, with one or two doubtfulcases, the figures appear to be reliable for the unimolecular first step in thedecomposition. The results for the three aliphatic nitro-compounds 29and the two ketones 30332 are somewhat doubtful; the former because theauthors suspected that there may be a change of mechanism in the temper-ature range of the investigation; the latter because of the surprising andvariable behaviour shown by several simple ketones towards the presenceof nitric oxide. The decompositions of acetone,35 ethyl methyl ketone,36and methyl fi-propyl ketone31 are all catalysed by nitric oxide, but that ofdiethyl ketone 30 is inhibited by it. The results for cis- and tram-dichloro-ethylene,, are derived from the observations at high pressures when chainreactions are suppressed.These authors give details of the changes in theArrhenius parameters with pressure, and in a further paper 37 discuss thechain mechanism. Clarke and Pritchard have pointed out that theirresults for the series of ketones show that replacement of CH, by CF, hasvery little effect on either the activation energy or the frequency factor andhence the effective number of oscillators contributing to the reaction is notdependent on the physical mass of the relevant groups. Szwarc andTaylor28 identify the value of 72 kcal. mole-l for the activation energy ofthe decomposition of acetone with D(CH3-COCH,) and from this theydeduce a value of 17 kcal.mole-l for D(CH,-CO). These authors have alsoreviewed critically the validity of the toluene carrier technique. Theyconclude that for pyrolyses which yield methyl radicals the method willgive reliable results provided the methyl radical concentration is not veryhigh and that the method is quite reliable for the pyrolysis of bromides andsubstances which yield a large radical which then decomposes into a smallerradical and a stable species, the latter being used to follow the reaction.A value of G5.7 kcal. mole-l has been deduced 38 for the activation energyof the reaction H + H,CO __t H, + HCO from studies of the pyrolysis ofl6 M. Volpe and H. S. Johnston, J . Amer. Chem. SOC., 1956, 78, 3910.28 M. Szwarcand J.W. Taylor, J . Chem. Phys., 1955, 23, 2310.lS K. A. Wilde, Ind. Eng. Chem., 1956, 48, 769.8o C. E. Waring and C. S. Barlow, J . Amer. Chem. Sot., 1956, 78, 2048.81 C. E. Waring and V. L. Garik, ibid., p. 5198.82 A. M. Goodall and K. E. Howlett, J., 1956, 2640.aa S. J. W. Price, R. Shaw, and A. F. Trotman-Dickenson, ibid., p. 3855.34 F. H. Pollard, H. S. B. Marshall, and A. E. Pedler, Trans. Paraday Sot., 1956,35 C. E. Winkler and (Sir) C. N. Hinshelwood, Proc. Roy. Sot.,- 1935, A , 149, 340.s6 C. E. Waring and M. Spector, J . Amer. Chem. SOG., 1955, 77, 6453.87 A. M. Goodall and K. E. HowIett, J., 1956, 3092.98 R. Klein, M. D. Scheer, and L. J. Schoen, J . Amer. Chem. SOC., 1956, 78, 50Idem, ibid., p. 3903.52, 59KINETICS OF CHEMICAL CHANGE.25formaldehyde. Further confirmation of the molecular mechanism for theisomerisation of cyclopropane has been provided by McNesby and Gordon 39and Lindquist and Rollefson.40 The former heated cyclopropane-deuteriummixtures and found that no deuterated cyclopropanes or propenes are formed.The latter investigated the isomerisation of cyclopropane and rHflcyclo-propane, and found that the ratio of the rate constants (cyclopropaneltritiumcompound) = (0.63 & 0-02) exp [(825 -+ lO)/RT] in the range 447-555".The expression derived from transition-state theory is 1.16 exp (800/RT) andthe ratio of the frequency factors calculated from Slater's theory is 1-62.Both theories thus predict a frequency-factor ratio of greater than unity, incontrast to the experimental value of 0.63 & 0.02.A similar effect hasbeen found by Gray and Pritchard 41 who have found that the high-pressurerate constant for the thermal decomposition of octadeuterocyclobutane istwice that for cyclobutane. These authors point out that if the criticalco-ordinate is either a C-H or an H-H distance, and if the two activationenergies are equal, then Slater's theory would predictHowever, the cause of this apparent discrepancy may lie in a small differencein activation energy.The bimolecular decomposition of nitrogen dioxide has been re-examinedby Rosser and Wise 42 and by Ashmore and Le~itt.*~ At all except the lowestpressure the results for the reaction NO, + NO, + 2N0 + 0, agree withthose of Boden~tein.~~" At the lowest pressures and during the initial stagesof the reaction, Ashmore and Levitt found deviations from strict bi-molecularity which they account for by the participation of the reactionsNO, + NO, 4, NO + NO, and NO, + NO, t NO + NO, + 0,.Inboth studies the reaction was followed by measurement of changes in opticaldensity, the latter workers 43 using a logarithmic photometer. The halogen-catalysed thermal decomposition of nitrous oxide has been studied; thereaction was found to be of the first order in nitrous oxide and in halogenatom concentration. The pre-exponential factors and activation energiesfor the three cases of catalysis by C1, Br, and I atoms are 1.3 x 1014 and33.5, 2.0 x 1014 and 37, and 2.8 x 1014 and 38, respectively; the pre-exponential factors are in C.C./(mole sec.) units and the activation energiesin kcal. mole-l. It has also been found45 that the nitric oxide formed inhigh yield in the initial stages of the thermal decomposition of nitrous oxidequickly inhibits its own further formation and that the chemiluminescenceof this decomposition is closely related to this inhibiting effect. The chemi-luminescence is ascribed to the reaction NO + 0 + NO, + hv. A mech-anism for the decomposition is discussed by these workers. The catalysisby nitric oxide of the cis-trans-isomerisation of dideuteroethylene has beenkc0 (C4H8) lk,(C,D*) = 4 23s J. R. McNesby and A. S. Gordon, J . Chem. Ph-ys., 1956, 25, 582.40 R. H. Lindquist and G. K. Rollefson, ibid., 1956, 24, 725.41 B.F. Gray and H. 0. Pritchard, J., 1956, 1002.42 W. A. Rosser and H. Wise, J . Chem. Phys., 1956, 24, 493.43 P. G. Ashmore and B. P. Levitt, Research, 1956, 9, s25.4aa Cf. M. Bodenstein, Z.$hys. Chem., 1922, 100, 68.44 F. Kaufman, N. J. Gerri, and D. A. Pascale, J . Chem. Phys., 1956, 24, 32.46 F. Kaufman, N. J. Gerri, and R. E. Bowman, ibid., 1966, 25, 10626 GENERAL ANL? PHYSICAL CHEMISTRY.studied by Rabinovitch and Looney.46 The reaction is of the first orderin ethylene and in nitric oxide, the activation energy being 27.5 kcal. mole-1.These authors conclude that the isomerisation involves the opening of thedouble bond.Stepukhovich and his collaborators 47 have continued their studies of thethermal decomposition of gaseous hydrocarbons.'They find that tetra-methylethylene greatly accelerates the decomposition of propane at 590°,but the acceleration decreases with decreasing temperature until at 522" thissubstance retards the decomposition of propane. Similar results werefound for the decomposition of isobutane. The thermal decomposition ofbutyl bromides has been inve~tigated.~~ The secondary and tertiarybromides show first-order kinetics whereas the order for the normal andiso-butyl bromides is 1.5, owing to a chain mechanism. The observationsfor the first two bromides are in agreement with those of Maccoll et al. (seeAnnual Reports, 1955, 52, 10). In this field it has also been found49 (inagreement with Maccoll et al.) that the thermal decompositions of n-propyland isopropyl bromide are not straightforward unimolecular eliminations ofHBr.A study of the pyrolysis of [l-14C]propane has shown 50 that the12C-12C bonds in this molecule break about 8% more frequently than12C-14C bonds and this result is unaffected by the presence of nitric oxide.This difference is the same as that found by Stevenson et aL51 between12C-12C bonds and 12C-13C bonds. The velocity constant for the decom-position of photo-excited aniline molecules has been determined ; 52 thefrequency factor and activation energy of the process, which probablyinvolves the breaking of the C-N bond, are 3.6 x 1013 sec.-l and 12 kcal.mole-l, respectively. It is interesting that the frequency factor for thedecomposition of an excited molecule lies in the so-called '' normal range."Results for other excited molecules would be very interesting.A detailedexamination of the mercury-photosensitised decomposition of C,H,, C,D4,and cis-C,H,D, has been made,S3 and the results further confirm earlierwork by the same authors indicating that hydrogen and acetylene areformed from ethylene by direct molecular decomposition and not via theformation of free radicals. This process shows an isotope effect and exten-sive isotopic isomerisation also occurs ; cis-C,H2D2 isomerises to the antias well as the tram form. The change is considered to take place duringcollisional deactivation of energy-rich ethylene molecules. From a quantit-ative study of the rate of production of hydrogen it was concluded that theremust be two types of energy-rich ethylene molecules involved, only one of4 G B.S. Rabinovitch and F. S. Looney, J . Chem. Phys., 1956, 23, 2439.4 7 A. D. Stepukhovich and E. E. Nikitin, Doklady Akad. Nauk S.S.S.R., 1955, 105,48 G. B. Sergeev, ibid., 1966, 106, 299.d9 N. N. Semenov, G. B. Sergeev, and G. A. Kapralova, ibid., 1055, 105, 301.so H. M. Frey, C. J. Danby, and (Sir) C. N. Hinshelwood, Proc. Roy. SOC., 1956, A ,61 D. P. Stevenson, C. D. Wagner, 0. Beeclr, and J. W. Otvos, J . Chem. Phys., 1948,62 B. Stevens, ibid., 1956, 24, 1372.63 A. B. Callear and R. J. Cvetanovic, ibid., p, 873.54 R. J. Cvetanovic and A. B. Callear, ibid., 1955, 23, 1182.997.234, 301.16, 993KINETICS OF CHEMICAL CHANGE. 27which can decompose. In contrast to the above conclusions concerning theproduction of H, and C,H,, Varnerin and D o ~ l i n g , ~ ~ from an investigationof the thermal decomposition of C,H6-CD, mixtures, conclude that ethanedecomposes into two methyl radicals which start a chain mechanism, andthat a negligible amount of H, and D, are formed by direct moleculardecomposition.Benson 56 has given a detailed critical analysis of theTABLE 2. Values of ET - +ED and A,/~/AD for radical reactions involving ahydrogen-atom transfer. E T i s the activation of energy of the reactionR* + HX+ RH + *X and ED that of the dimevisation R- + R*-+R, ; AT and AD are the corresponding fire-exponential factors.RadicalCH,*,,Molecule (HX)D,D,CH,*CO*CH,H,CH,*CD,*CD2*CH,CH,*CH,*CH,CH,*CH,*CH,*CH,CH,*CH(CH,),H,HD (to give CF,H)HD (to give CF,D)D4CH,CH,*CHa*CH,*CH,CH;CH,*CH,*CH,D,H',E T - *ED(kcal .)11.912.1 f 0-69.8 f 0.410.2 f 0.59.311.46.5 f 0.55.1 f 0-34-7 f 0.39.5 f 0.710.5 f 1.510.2 f 1.510.2 f 0.79.5 f 25.5 f 19.78.87.66.25.34.7(3.0)1.78.0(7.7)6.07.2 f 0.58.0 - 9.24.98.5 f 0.1A T / ~ / A D[c.c. /(mole sec. )]4-13-9 x 1048.5 x 104-~3 x 104~ 1 . 5 x 1 0 45.8 x 1048.4 x 10412 x 1049-7 x 1 0 46.0 x 1047.2 x 104(0.73 x 104)0.3 x 104(5.8 x 104)6.8 x lo44.5 x 10'1.8 x 10'C4.8 x 10'(106 - 108)-Ref.58596bfi261, I, I633 ,I ,ii6k, I5 ,,.I 1,.,,#,,66676869(a) For the removal of a secondary H atom.( b ) For the removal of either a primary H atom OY a secondary D atom.(c) Calc.from the published figures for the ratios of the steric factors, PT/~/€'D,by assuming that the collision-number ratio Z , / l / Z , = lo7 [c.c./(mole sec.)]f.available experimental work on the pyrolysis of dimethyl ether. He hasput forward a chain mechanism for the decomposition and has derivedvalues for the rate constants of some of the reactions involved. The thermaldecomposition of some alkyl nitrites has been investigated. 57Reactions involving radicals. The activation energies and pre-exponentialfactors resulting from new investigations of the hydrogen-transfer reactionsof radicals are given in Table 2. The radicals have been produced mainly bythe photolysis of ketones.The agreement between the two schools ofss K. E. Varnerin and J. S. Dooling, J . Amer. Chent. SOC., 1956, 78, 2042.5 6 S. W. Benson, J . Chem. Phys., 1956, 25, 27.6 7 J. B. Levy, J . Amer. Chem. SOC., 1956, 78, 1780; Ind. Eng. Chenz., 1956, 48, 76228 GENERAL AND PHYSICAL CHEMISTRY.workers on the trifluoromethyl radical is very good, particularly sincedifferent methods and radical sources were used; one school 62s 63 usedthe photolysis of (CF,),CO, while the photolysis of CF,*N=N*CF, was usedby the other.B4* 65 Workers in both schools have arrived at the same generalconclusion, that the activation energies for the hydrogen-transfer reactionsof CF, radicals are 2-3 kcal. mole-1 less than those of the correspondingCH, radical reactions. Ayscough and Polanyi 63 have given a detaileddiscussion of their results for trifluoromethyl radical reactions in terms ofcollision theory and transition-state theory, and have calculated the pre-exponential factors of a number of these reactions.The results obtained 64for the reaction of CF, radicals with CH, together with those 70 for thereaction of CD, radicals with CF,H permit an estimation of D(CF,-H). Avalue of 102 & 2 kcal. mole-l was obtainedJ70 based on D(CH,-H) =102.5 & 1 kcal. mole-l.A new theory has been developed for the rotating-sector method ofinvestigating radical recombination rates.71 It includes the situation whenthe radicals are removed by both first- and second-order reactions.Appliedto the case of CH, radicals the recombination rate constant was found to be2.2 x lo1, c.c./(mole sec.) which is about half the value hitherto accepted.The method has also been applied to CF, radicals,72 yielding a rate constantof 2.3 x lo1, c.c./(mole sec.). A collision diameter of 4 A being assumed,this means that ED (Table 2) cannot be greater than 1.5 kcal. mole-l. Hencethe figures given in column 3 of Table 2 must be close to the true values forET. The sector method has also been applied to the recombination ofn-propyl radicals; 73 a value of 6 x 1015 c.c./(mole sec.) was obtained forthe sum of the rate constants of disproportionation and recombination. Theauthors, in discussing likely errors, state that this figure may be as much as20 times too large.It appears probable, however, that n-propyl radicalsrecombine at almost every collision. A very extensive study of the be-haviour of ethyl and propyl radicals at room temperature has been madeby Bradley, Melville, and Robb.',. '59 76 Two different methods were used6 8 J. R. McNesby, A. S. Gordon, and S. R. Smith, J . Amer. Chem. SOG., 1956,78, 1287.69 J. Chanmugam and M. Burton, J . Amer. Chem. SOC., 1956, 78, 509.6o H. Gesser and E. W. R. Steacie, Canad. J . Chenz., 1956, 34, 113.61 J. R. McNesby and A. S. Gordon, J . Amer. Chem. SOC., 1956, 78, 3570.62 P. B. Ayscough and E. W. R. Steacie, Canad. J . Chem., 1956, 34, 103.63 P. B. Ayscough and J. C. Polanyi, Tvans. Faraday SOC., 1956, 52, 960.64 G. 0. Pritchard, H. 0.Pritchard, and A. F. Trotman-Dicltenson, Chem. and Ind.,6 5 G. 0. Pritchard, H. 0. Pritchard, El. I. Schiff, and A. F. Trotman-Dickenson,O 6 R. M. Smith and J. C. Calvert, J. Amer. Cheun. SOG., 1956, 78, 2345.13' R. K. Brinton and E. W. R. Steacie, Canad. J . Chem., 1955, 88, 1840.6 8 C. A. Heller and A. S. Gordon, J . Phys. Chem., 1956, 60, 1315.139 J . T. Gruver and J. C. Calvert, J . Amer. Chem. SOG., 1956, 78, 5209.70 G. 0. Pritchard, H. 0. Pritchard, H. I. Schiff, and A. F. Trotman-Dickenson.71 A. Shepp, J . Chem. Phys., 1956, 24, 939.72 P. B. Ayscough, ibid., p. 944.73 S. G. Whiteway and C. R. Masson, i b i d . , 1956, 25, 233.74 J. N. Bradley, H. W. Melville, and J. C. Robb, Proc. Roy. Sot., 1956, A , 236, 318.76 Idem, ibid., p. 333.76 Idem.ihid.. D. 339.1955, 564.Trans. Faraday Sot., 1956, 52, 849.Chem. and Ind., 1955, 896KINETICS OF CHEMICAL CHANGE. 29for the production of ethyl radicals-the photosensitised decomposition ofhydrogen in presence of ethylene and the photolysis of diethyhercury-andinvestigations were carried out over a wide range of conditions. From thedeterminations of the ethane : butane ratio, these authors conclude 74 that,besides the normal two-body reaction between ethyl radicals, a three-bodyprocess is important at high pressures, while at low pressures wall reactionsbecome important. In addition the behaviour of " hot " ethyl radicalsmust be taken into account, The quantitative effect of these factors agreesclosely for the two methods of production of ethyl radicals.It is suggestedthat these factors are responsible for the varied results obtained in the pastby different workers. Bradley, Melville, and Robb's 74 observationsindicate that hot ethyl radicals only disproportionate and do not dimeriseand it is estimated that 105-106 collisions of a hot radical with neon arerequired for moderation, while ethylene is about five times more efficient.Estimates are also made of the ratio of the rate constants of the threedbodyand normal two-body reactions between ethyl radicals. The extrapolatedvalue of the ratio ethane : butane at zero pressure was found to be 0.86;this ratio decreases with increasing pressure, its average value being 0.43,which is close to that found by Ivin and S t e a ~ i e .~ ~ However, there appearsto be a considerable discrepancy between these results and the value of 0.15,for the ratio kdjqr.lk-mb. which Smith, Beatty, Pinder, and LeRoy 78have concluded is the best estimate from the most reliable investigations inthis field. Bradley, Melville, and Robb 75 studied the collision efficiencyfor the reaction of ethyl radicals by allowing this reaction to compete withthe destruction of the radicals at a molybdenum oxide surface. Mass-spectrometric analysis was used, which obviated the need for quantitativeobservations of the blueing effect of the oxide. The collision efficiency wasfound to be 0.15 -+ 0.03, corresponding to k, + krecomb. = 2.6 x 1013c.c./(mole see.). This is in excellent agreement with the value of 2.2 x 1013found by Ivin and S t e a ~ i e .~ ~ The work on propyl radicals,76 produced bythe photosensitised decomposition of hydrogen in the presence of propene,was carried out under conditions which favoured reaction by the normaltwo-body process. The average propane: hexanes ratio was found to be1.05 & 0.06, showing that propyl radicals disproportionate more readilythan ethyl radicals. It was also shown that the attack of propene byhydrogen atoms produces only 7.5% of m-propyl radicals, the remainderbeing isopropyl radicals. For the latter radical Heller and Gordon 68 findKaiepr./Kmomb. = 0-6 at 200" from studies of the photolysis of diisopropylketone. Brinton and Steacie 67 have studied the reactions of ethyl radicalsproduced by the photolysis of diethyl ketone; at the highest pressures theyfound evidence of a second butane-forming reaction in addition to thedimerisation of the radicals. At high intensities of illumination and lowketone pressures, when the ethylene produced comes solely from the dis-proportionation, the ratio of rate of ethylene production to rate of butaneproduction was 0.12 and constant over a wide range of conditions.This7 7 K. J. Ivin and E. W. R. Steacie, Proc. Roy. SOL, 1951, A , 208, 25.78 M. J. Smith, P. J. M. Beatty, J. A. Pinder, and D. J. LeRoy, Canad. J . Chem.,1955, 33, 82130 GENERAL .\NU PHYSIC.41, CXEMISTHY.result is close to the best value of 0-15 for kdispr./kmcomb. selected by Smithet aZ.78 Brinton and Steacie conclude that both the disproportionation andrecombination of ethyl radicals are homogeneous and independent ofpressure down to 0.01 mm.(cf., however, ref. 74). Results obtained forkdispr./hmcomb. for other radicals are 0.125 at 100" for n-propyl radicals 73and 1-67 at 25' for sec.-butyl radicals.69The free-radical reactions resulting from the photolysis of keten (aloneand in the presence of hydrogen and deuterium) have been studied by twogroups of workers.59* 60* 79 Unfortunately, the conclusions reached differseriously. Chanmugam and Burton 59* 79 consider that their observationsshow that the reaction CH, + CH,+ CH, has a small activation energyand is a significant reaction even at room temperatures, and that the dimeris-ation of methyl radicals cannot account for all the ethane produced in theirsystem.With CD, present they claim that the reaction CH, + CD,+CH,D, + CD, occurs. On the other hand, Gesser and Steacie 6o claim thatthe methylene radicals undergo the reaction CH, + H, + CH, + H(not CH,) and that the dimerisation of methyl radicals is the sole source ofethane. From their observations at the lower temperatures, Gesser andSteacie estimated that the activation energy of the reaction CH, + H, ---tCH, + H is 0.8 kcal. mole-l greater than that for CH, + CH,*CO +C,H, + CO and from this they deduce a lower limit of 103 kcal. mole-l forD(CH,-H). Methylene radicals have also been produced by the flash photo-lysis of keten.8O The observations show that methylene radicals must reactvery rapidly with keten (collision efficiency > to give cyclopropanone inone step, which then decomposes into the radicals *CH,-CH,-CO and*CH,-CO-CH,-, the former having a long life.These authors are of theopinion that the methylene radicals are produced in the singlet state by theflash photolysis. Methylketen has also been photolysed; the productssuggest that the primary act produces ethylidene radicals.From a study of the photolysis of (CF,),CO, Ayscough and Steacie 82have postulated the existence of two types of excited ketone molecules inthe system, only one of which has sufficient energy to decompose. Therelative rate constants of various energy-transfer processes involving thesespecies have been calculated. A new determination of the rate of reactionbetween nitric oxide and methyl radicals, produced by pyrolysis of dimethyl-mercury, has been made.83 A mass spectrometer was used and the values ofthe rate constants obtained are 1-4 x 1011 at 900" and 1.3 x lo1: c.c./(molesec.) at 480".The authors suggest that the rate constant may be higherthan this at higher pressures (they used -1 mm. of helium) and point outthat the results at various temperatures now available for this reactionindicate that the activation energy is probably zero. A similar study 83ahas provided a rough value of 10-3-104 for the collision efficiency of the79 J. Chanmugam and M. Burton, ibid., 1956, 34, 1021.G. B. Kistiakowsky and K. Sauer, J. Amer. Chem. SOL, 1956, 78, 5699.G. B. Kistiakowsky and B. H. Mahon, J - Chem.Phys., 1956, 24, 922.P. B. Ayscough and E. 'CV. R. Steacie, Proc. Roy. SOC., 1956, A , 234, 476.W. A. Bryce and K. U. Ingold, J . Chem. Phys., 1955, 23, 1968.K. U. Ingold and W. -4. Bryce, ibid., 1956, 24, 360reaction between methyl radicals and oxygen. Lossing et aLN have eni-ployed a mass spectrometer to investigate the mercury-photosensitiseddecomposition of olefins into free radicals. Ethylene decomposes primarilyby a molecular split; propene gives mainly allyl radicals and hydrogenatoms; but-l-ene gives allyl and methyl radicals, although splitting at aC-H bond also occurs to a smaller extent, and but-2-ene and isobutene bothdecompose by the splitting of a C-H bond. The subsequent reactions ofthe radicals produced were also studied.The decomposition of primaryand secondary n-butyl radicals has been investigated ; 85 they were producedby photolysis of acetone in the presence of [2 : 2 : 3 : 3-2H,]n-butane andthe products were identified by mass spectrometry and vapour-phasechromatography. The results show that hydrogen atoms in a free radicalcannot wander by an intramolecular process and that the radicals decomposemainly into a small radical (ethyl or methyl) and an olefin (ethylene orpropene). A value of 24 kcal. mole-l for the activation energy of the decom-position of secondary butyl radicals into propene and methyl radicals hasbeen obtained from work on the photolysis of a-methylb~tyraldehyde.~~The rather disturbing suggestion by Boynton and Taylor that studies ofmethyl-radical reactions may be appreciably affected by reaction of theradicals with mercury vapour to give dimethylmercury has been disproved bythe results of Kutshke and McElcheran *’ who havere-examined the photolysisof acetone in a system carefully kept free from mercury contamination.Reactions involviszg atoms.Relatively few quantitative results forvelocity constants and Arrhenius parameters of reactions involving atomshave been published during the past year. Cvetanovic 88 has studied thereaction of oxygen atoms, produced by the mercury-photosensitised decom-position of nitrous oxide, with acetaldehvde and acetaldehyde-ethylenemixtures at room temperature. From the results, together with his results 89for the ethylene reaction, Cvetanovic estimates that the activation energy ofthe acetaldehyde reaction is about 3 kcal.mole-l. has alsoreviewed the work on the reaction of oxygen atoms with various olefins andhas formulated certain rules concerning various possible mechanisms. Hehas estimated the relative rates of reaction at 2 5 O for a number of olefinsbased on n-butane as standard (= These are : cis-but-&ene,4.8 x isobutene, 6.9 x lo3; but-l-ene, 1.4 x ethylene,2-2 x lo4; acetaldehyde, 1.5 x n-butane, A study of thenitrogen afterglow bv a technique involving the simultaneous use of a massspectrometer and a photomultiplier has been made 91 which has provided avalue of 2 x c.c.2/(molecules2 sec.) for the termolecular rate constantfor the recombination of nitrogen atoms.This value is about one tenthof that found for recombination of iodine and bromine atoms. The84 I?. P. Lossing, D. G. H. Marsden, and J . B. Farmer, Canad. J . Chein., 1356, 34,J. R. McNesby, C. M. Drew, and A. S. Cardon, J . Chew Phys., 1956, 24, 1260.C. F. Boynton, jun., and H. A. Taylor, ibid., 1954, 22, 1929.K. 0. Kutschke and D. E. McEIcheran, ibid., 1956, 24, 618.Idem, J . Chem. Phys., 1955, 23, 1376.Idem, ibid., 1956, 25, 376.Cvetanovic701.88 R. J. Cvetanovic, Canad. J . Chem., 1956, 34, 775.91 J. Berkowitz, W. A. Chupka, and G. B. Kistiakowsky, ibid., p. 45732 GENERAL AND PHYSICAL CHEMISTRY.observations indicate that the reaction involves two 4S nitrogen atoms pro-ducing a 52: molecule which then undergoes a collision-induced radiationlesstransition to a 311, molecule.Values for the termolecular recombinationrate constants for iodine atoms 92 and bromine atoms 93 at high temperature(1000-1600" K) have been obtained by the shock-tube technique, Theresults for various gases as third bodies are given. These velocity constants,together with those obtained by flash photolysis at very much lower tem-peratures, establish the reality of a negative temperature coefficient beyondany doubt.An extensive investigation of the rates of reaction of sodium atoms witharomatic halides has been made 94 by use of the diffusion-flame technique.In addition to the halogen atom removed by the sodium, the halides con-tained a second unreactive substituent attached to the benzene ring.Bond-energy effects are shown to be negligible, and the gradations in velocityconstant are discussed in terms of the stabilisation of the transition state bythe participation of additional ionic structures arising from the presence ofthe second substituent. Winkler and his collaborators have continued theirinvestigations of the reactions of active nitrogen with various substrates-alkyl chlorides,95 methane and ethane,96 dimethyl- and diethyl-merc~ry,~~and a~etonitrile.~~ Evans and Winklerg9 have concluded that the mainactive species in this system is atomic nitrogen, but the evidence suggeststhat there is more than one species involved. They consider that vibration-ally excited molecules are the most likely possibility. The reactions ofactive nitrogen with organic substrates have been reviewed as a whole looand a unified mechanism has been outlined to account for the more importantfeatures of these reactions.The relative efficiencies of the addition of hydrogen atoms to ethyleneand propene have been re-investigated by Bradley, Melville, and Robb.lolUsing an improved molybdenum oxide technique, they obtained resultswhich are in satisfactory agreement with those obtained by other methods,and the ratio of the efficiencies H + propene : H + ethylene z 1-5 appearsto be well established. The investigation also shows that the collisionefficiencies of the radical reactions ethyl + ethyl, ethyl + propyl, andpropyl + propyl are all approximately equal.It has been discovered thattraces of oxygen greatly accelerate the hydrogen-deuterium exchangereaction.102 This is due to a chain reaction.This exchange reaction hasalso been very carefully re-investigated lo3 over the temperature range92 D. Britton, N. Davidson, W. German, and G. Schott, J. Chem. Phys., 1956,25,804.93 D. Britton and N. Davidson, ibid., p. 810.94 F. Riding, J. Scanlan, and E. Warhurst, Trans. Faraduy Soc., 1956, 52, 1354.95 B. Dunford, H. G. V. Evans, and C. A. Winkler, Canad. J. Chem., 1956, 34, 1074.9 6 P. A. Gartaganis and C. A. Winkler, ibid., p. 1457.97 D. A. Armstrong and C. A. Winkler, ibid., p. 885.O 8 W. Forst and C. A. WinMer, J. Phys. Chem., 1956, 80, 1424.O9 H. G. V. Evans and C. A. Winkler, Canad. J . Chem., 1956, 34, 1217.loo H. G. V. Evans, G.R. Freeman, and C. A. Winkler, ibid., p. 1271.lol J. N. Bradley, H. W. Melville, and J. C. Robb, Proc. Roy. Soc., 1956, A , 236,lo2 R. Kiein, M. D. Scheer, and L. J. Schoen, J. Amer. Chem. Soc., 1956,78,47.lo3 G. Boato, G. Careri, A. Cimino, E. Molinari, and G. G. Volpi, J. CkeM. Phys.,454, 446.1956, 24, 783KINETICS OF CHEMICAL CHANGE. 33916-1010" K. Irreproducible results were obtained unless the reactionvessel was surrounded by an evacuated quartz jacket which preventeddiffusion of air into the system through the reaction vessel walls. Theexchange rates obtained when diffusion of air was excluded were a factorof 2 lower (cf. ref. 102) than those obtained by previous workers. A valueof 59.8 & 0.4 kcal. mole-l was obtained for the total activation energy.Theauthors consider that the new results provide a stringent test of the transi-tion-state theory and they conclude that the theory can account satisfactorilyfor the observations.has been used to study the reaction H + 0,- OH* + O,, which isfollowed by OH* ---.t OH + hv. The preliminary results indicate that thefirst reaction probably goes at almost every collision and that the life-timeof the excited hydroxyl radical is about 8 xMolecuZeaoZec.uZe reactions. Further details of the work of Ashmoreand Levitt lo5 on the H2-NO, reaction have appeared, together with adescription of the logarithmic photometer lo6 which was used in the investig-ation. At 400" c, nitrogen dioxide in presence of excess of hydrogen israpidly and completely removed without change in total pressure ; the rateis much greater than that of the reaction 2N0, ----t 2N0 + 0,.Theinhibition of the reaction by nitric oxide is not due to the reverse of thereaction NO, + H, + NO + H,O, but is probably due to a chain reaction,the termination involving nitric oxide. Water has very little effect on theinitial rate but it accelerates the final stages of the reaction. Large amountsof oxygen retard the reaction. The authors conclude that further work isnecessary before the nature of the chain reaction can be established. Thekinetics of the CF,-CN-butadiene cyclisation reaction have been studied ; 10'this bimolecular reaction is a modification of the Diels-Alder condensationin which hydrogen is eliminated.The activation energy is 21.5 kcal. mole-1and the pre-exponential factor is 2.1 x lo9 c.c./(rnole sec.), the latter beingconsiderably less than the " normal " value for bimolecular reactions, andis characteristic of this type of condensation. The reaction between diethylether and nitrogen dioxide over the range 120-200" has been shown to bepredominantly bimolecular with an activation energy of 22 kcal. mole-I.The products are numerous and one of them, nitric oxide, acts as an in-hibitor.lo8 Between 0" and loo", pressure measurements indicate theformation of ether complexes with nitrogen dioxide. The inhibiting effectof nitrogen dioxide on the reaction between nitric oxide and dinitrogenpentoxide has been studied with a fast-scanning infrared spectrometer.1mValues of k,[k6 were obtained at various temperatures and total pressures,the rate constants corresponding to the reactions in the mechanism :kl k.klA modified form of the diffusion-flame techniquesec.N205 __L_ NO, + NO,; NO + NO, __)_ 2N02lo4 D.Garvin and J. D. McKinley, J. Chem. Phys., 1956, 24, 1256.lo6 P. G. Ashmore and B. P. Levitt, Trans. Furaduy SOC., 1956, 52, 836.lo6 P. G. Ashmore, B. P. Levitt, and B. A. Thrush, ibid., p. 830.lo' J. M. S. Jarvie and G. J. Janz, J. Phys. Chem., 1956, 60, 1430.108 E. A. Blyumberg, V. L. Pikayeva, and N. M. Emanuel, 2hur.ji.z. Khim., 1966,109 C . Hisatsune, A. P. McHale, R. E. Nightingale, D. L. Rotenburg, and B. Craw-29, 1569.ford, jun., J. Chem. Phys., 1955, %, 2467.REP.-VOL.LIII 34 GENERAL AND PHYSICAL CHEMISTRY.The hydrogen-bromine reaction has been investigated at 1000-1500" Kby the shock-tube technique. The experiments provide qualitativeinformation about the relative rates of the reactions comprising the well-known mechanism under non-steady-state conditions. The exchangereaction between B2D6 and B,H, at 80" has been studied by infrared spectro-scopy and by mass spectrometry.l12 Deuterium enters the pentaboraneby two main processes-by a direct exchange reaction which is almostexclusively restricted to the non-bridge hydrogens of the pentaborane, andb y synthesis following the pyrolysis of the diborane. The deuterium atomsenter singly during the exchange reaction and tracer studies with l0B showthat the boron atoms are not involved in the process.The reaction betweenB,H6 and PH, to give BH,*PH, (solid) has been shown to be a homogeneousgas reaction unaffected by the surface of the solid p r 0 d u ~ t . l ~ ~ A mechanismfor the reaction is suggested and the activation energy of the first stepB,H, + PH, + RH,*PH, + BH, is 11.4 kcal. mole-l with a steric factorof about 3 x [based upon a collision number of lo1* c.c./(mole sec.)].Varnerin and Dooling 114 have investigated the thermal reaction betweenC,H, and D,. The initial rates of formation of the numerous productswere measured by mass spectrometry. A free-radical mechanism is sug-gested and estimates are made of the overall activation energies for therates of disappearance of the reactants and of appearance of various pro-ducts.These are compared with theoretical estimates. Schissler andStevenson 115 have continued their mass-spectrometric studies of the gas-phase reactions between molecules and molecule-ions. In addition toreactions of the type X+ + HY + XH+ + Y, they give results forseveral reactions between simple hydrocarbons and carbonium ions. Forthe latter type, however, they emphasise that the simple interpretation ofthe reaction cross-sections (because of their dependence on certain experi-mental parameters) as bimolecular velocity constants is not strictly valid.Field et aZ.l16 have also published results for some examples of the secondtype of reaction; they concluded that the polarisation force between thecarbonium ion and the molecule is the dominant factor in determining thereaction cross-section.The kinetics of the equilibrium 2HI 4 H, + I, have been carefullyinvestigated from 600 to 775" K with a flow method.l17 The two reactionswere found to be strictly bimolecular and the results agree with extra-polations of previous results obtained at lower temperatures.The velocityconstants of the forward and reverse reactions are, respectively, 3-59 x1015 exp (- 49,2001RT) and 1-23 x 1015 exp (-41,0001RT) c.c./(mole sec.).Graven considers that his results disprove the suggestion 118 that above600" J< an atomic mechanism should play an appreciable part in the110 D. Britton and N. Davidson, J . Chenz. Phys., 1955, 23, 2461.111 J. J. Kaufman and W. S. Koski, ibid., 1956, 24, 403.112 W.S. Koski, J. J . Kaufmau, L. Friedman, and A. P. Irsa, ibid., p. 221.113 H. Brumberger and R. A. Markus. ibid., p. 742.114 R. E. Varnerin and T. S. Dooling, J. Arizey. Chew SOL , 1956, 78, 1119.116 D. 0. Schissler and D. P. Stevenson, J . Chem. Plays., 1956, 24, 926.116 F. H. Field, J . L. Franklin, and F. W. Lamp. J . A ~ M P Y . Chem SOC., 1956, 78, 5697.117 W. N. Graven, ibid., p. 3297.11s S. IV. Eenson and H. Srinivasan, J. CItent. Phys., 1955, 23, 300KINETICS OF CHEMICAL C:HANGE:. 36reactions, becoming dominant above 900" K. An attempt 119 to measurethe rate of exchange of 18F atoms between HF and variaus fluorinatedmethanes has shown, in contrast to the results for similar experiments 120on the exchange of isotopic chlorine between HC1 and chlorinated methanes,that no exchange occurs.The relative rates of exchange of 131 I between I, andcertain alkyl halides have been measured.121 The mathematical analysis ofthis type of system of competitive isotopic exchange reactions is also discussed.Radiation Chemistry.-In addition to the usual annual reviews on thistopic,lB collections of abstracts of the published and unclassified reportliterature have appeared3 and two more accounts of recent Russian workin the field became available at the end of lastDosimetry. The yield for the ferrous sulphate dosimeter has beendetermined more precisely for 2 Mv electrons as G(Fe3+) = 15-45 & 0.11molecules per 100 ev. There are now several independent determinationsof this yield covering 3 Mv electrons, 32P electrons, 1 Mvp X-radiation andMCo y-radiation, which use power output, counting, ionisation chambers,or calorimetric measurements for determining the energy absorption.Allagree within the experimental errors and there seems to be no variationwith intensity from 0.1 to 2 x lo6 R per sec. Slightly lower yields ofG(Fe3+) = 14-15 0.6 and 13.4 & 0.6 are obtained with 10 kv and8 kv X-radiation, respectively, by using 0-1N-sulphuric acid and assumingthe energy for ion-pair production (W) in air to be 34 ev.Hart et aL8 have obtained G(Fe3+) for 3.3-21.2 Mev deuterons and for0-3-2 Mev protons produced by a cyclotron. The former increases from6.90 to 10.86 over this energy range, and the latter from 7-16 to 8.00.Thereis reasonable agreement with previous determinations for particular energies.The methods used to measure the energy inputs in a similar investigationof cyclotron-produced deuterons and wparticles have been described9Pucheault lo finds that, by using ferrous sulphate solutions containingboric acid, the yields of Fe3+ given by y-radiation and neutrons in reactorradiation are additive. Ceric sulphate, ceric sulphate-boric acid, andferriin solutions l1 are recommended for separating the y and neutron119 J. E. Boggs, E. R. Van Artsdalen, and A. R. Brosi, J . Awzer. Chein. SOC., 1956,77,6505.120 J . E. Boggs and I,. 0. Brockway, ibid., p. 3444.lP1 L. R. Darbee, F. E. Jenkins, and G. M. Harris, .I. Chenr. Yhys., 1956, 25, 605.Ann.Reports, 1955, 52, 42.a C. J. Hochanadel and S. C. Lind, Ann. Rev. Phvs. Chem., 1956, 7, 83; F. S. Dain-ton, Ann. Rev. Nuclear Sci., 1955, 5, 213.R. W. Clarke, A.E.R.E. Reports C/R 1575 ; Part 1, Theory, Interpretations, Waterand Aqueous Inorganic Systems. Part 2, Organic Compounds (including Polymeris-ation Reactions). Part 4,Solid Systems (excluding Organic Compounds). Part 5, Biochemistry and Radio-biology (excluding animal studies).Session Acad. Sci. U.S.S.R. on Peaceful Uses of Atomic Energy, July 1955. Part 1,Meetings of Chem. Div.Collection of Papers on Radiation Chemistry, Ahad. Nazrk S.S.S.H., 1955.E. J. Hart, W. J. Ramler, and S. R. Rocklin, Radiatio9z Kes., 1956Part 3, Gaseous Systems (excluding Organic Compounds).Part 6, Miscellaneous.* R.H. Schuler and A. 0. Allen, J . Chem. Phys., 1956, 24, 66.7 M. Cottin and M. Lefort, J . Chint. phys., 1956, 53, 267.9 R. A. Schuler and A. 0. Allen, Rev. Sci. Iizstr., 1955, 26, 1128.10 J. Pucheault, .I. Chim phys., 1956, 53, 705.l 1 Idem, ibid., p. 69736 GENERAL AND PHYSICAL CHEMISTRY.intensities. Nitrous oxide, which on radiolysis gives nitrogen, oxygen, andnitrogen dioxide, makes a convenient gas dosimeter 12 for 5 x 104-1010 Rand has a yield G(-N,O) = 12.Detailed investigations are reported l3 on silver-activated phosphateglass for dosimetry over the range 103-107 R, and Cellophane sheets dyedwith an azo-dye are also suggested.14 The latter show a linear change intransmittance for doses of WCo y-radiation from 2 x 105 to lo7 R, with a1.5% change in transmittance for 1 0 6 ~ .Electrons are 2.2 times moreeffective. A book on radiation dosimetry which is mainly of interest toradiologists has been p~b1ished.l~Gases. Two reviews have appeared 16 on experimental and theoreticalaspects of the excitation and ionisation of molecules by electron impact,mainly in mass-spectrometer conditions. Momigny l7 finds that doubleimpacts by electrons can occur in the ion source, so that excitation may befollowed by ionisation at the second impact. Ionisation and excitationenergies are obtained which agree with spectroscopic values where available.Ionising electrons of energies up to 1100 v have been used in the massspectrometry of several alkyl halides.18 It is observed that the number ofions from molecular fragments decreases with increasing electron energy.Perhaps the most important recent contributions to radiation chemistryfrom mass spectrometry are Schissler and Stevenson’s observations l9 onthe reactions between ions and molecules.The reaction H2+ + H2+H,+ + H is well known and has been used in the interpretation of theradiation-induced reactions of hydrogen. Other types of ion-moleculereactions now found include :Krf + H, __+ KrH+ + H CHS + CH4 + C,H,+ + HSCH4+ + CHI CH,+ + CH, CaHe+ + CaH, C4H$ + C,H(It is also important that specific rate constants have been estimated whichshow that almost every collision is effective in reaction. In similar studiesMeisels et aLZ0 find that charge transfer with bond breaking may occur:A+ + CH, + A + CH,+ + H.These observations confirm the earlysuggestion of Lind that such ion-molecule reactions are important in radi-ation chemistry, and they also point to a likely mechanism for the productionof high-molecular weight products in the irradiation of hydrocarbons.Hickam and Fox 21 have applied the retarding-potential differencemethod, previously used in the study of positive-ion formation, to study thecapture of low-energy electrons (<2 V) by sulphur hexafluoride. Measure-12 P. Harteck and S. Dondes, Nucleonics, 1956, 14, No. 3, 66.1s S. Davison, S. A. Goldblith, and B. €2. Proctor, ibid., No. 1, 34; N. J. Kreidl andG. E. Blair, ibid., No. 1, 50; A. L. Reigert, H. E. Johns, and J. W. T. Spinks, kbid.,No.11, 134.14 E. J. Henly and D. Richman, Analyt. $hem., 1956, 28, 1580.16 G. J. Hine and G. L. Bronnell (ed.), Radiation Dosimetry,’’ Academic PressInc., New York, 1956.l6 J. D. Craggs and C. A. McDowell, Rep. Progr. Phys., 1955, 18, 375; M. Kraus,A. L. Wahrhaftig, and H. Eyring, Ann. Rev. Nuclear Sci., 1955, 5, 241.17 J. Momigny, J. Chem. Phys., 1956, 26, 787.18 N. N. Tunitskii, S . E. Kupriyanov, and M. V. Tikhomirov, ref. 5, p. 223.l9 D. 0. Schissler and D. P. Stevenson, J. Chem. Phys., 1955,B. 1363 ; 1956,24,926.ao G. G. Meisels, W. H. Hamill, and R. R. Williams, ibid., 1956, 25;, 790.a1 W. 31. Hiclrarn and R. E. Fox, ibid., p. 643KINETICS OF CHEMICAL CHANGE. 37ments of W for polonium a-particles in H,, N,, CH,, air, BF,, H,S, NH,,C,H,, CO,, SO,, CCl,, and EtOH have given, in general, good agreementwith previous determinations.22Among induced chemical reactions, the fixation of nitrogen in air asnitrogen dioxide (liquid and gas) by pile radiation 23 and the polymerisationof ethylene by y-radiation have been reported.24 The latter occurs by a chainreaction to give a wax at -20 atm.and room temperature, with yields ofabout lo4 ethylene molecules polymerised per 100 ev absorbed. At 77.6"carbon tetrachloride vapour with a-particles gives an ion-pair yield 26 ofchlorine of 0.14 which is much less than 0.4 obtained in the liquid phase. Inelectron-irradiated mixtures of C,H, and C,D, it is found 26 that the H,, HD,and D, mixture produced is not equilibrated and its composition indicatesthat at least half of the hydrogen and deuterium must be formed as moleculesfrom the hydrocarbon.On the other hand this does not seem to be the casewith methane, for Meisels et aL20 find that electron-irradiated mixtures ofCH, + A + I, do not give much CH,I,. The ethyl group in the largeamounts of C,H,I found here is thought to originate in the ion-moleculereaction CH,+ + CH,+ C2H,' + H,..An interesting study of indirect action caused by tritium @-irradiationof water vapour has been made by Fire~tone.~' When small amounts of D,in H,O vapour containing T,O are used, HD is formed with G(HD) = 11 & 1,independent of the amounts of H,O, D,, or T,O present. The suggestedmechanism for HD formation isfi + Ha0 H + HOH + DZ+ HD + DHO+DI+HOD+DD+D-DaOn this basis G(HD) = G(-H,O).The number of water molecules decom-posed in the vapour is therefore about three times that observed in liquidwater, which is consistent with current ideas that radical recombinationoccurs in the ionisation tracks in liquids.Non-aqueous Ziqztids. There has been a comprehensive review of theradiation chemistry of organic compounds 2s and of reactions which mightbe useful in synthetic organic chemistry.eg Berry et aLso have made amore extensive investigation of the quenching of the racliation-inducedluminescence of 9- and m-terphenyl and 1 : 4-diphenylbutadiene in benzene,cyclohexane, and toluene. The observations are consistent with the earliersuggestion that quenching is due to interaction of the quencher and excited29 C.Biber, P. Huber, and A. Miiller, Helv. Phys. Actu, 1955, 28. 603.23 P. Harteck and S. Dondes, J . Chem. Phys., 1956, 24, 619; Nucleonics, 1966, 14,No. 7, 22; S. Y. Pshezhetsky, I. A. Myasnikov, and N. A. Buneev, ref. 4, p. 64; ref. 5,p. 133.a4 J. C. Hayward, U.S.A.E.C., N.Y.O., 1955, 3313.2ci W. Mund, P. Huyskens, and J. Dedaisieux, Bull. Clusse Sci., Acud. my. Belg.,1955, 41, 929.28 L. M. Dorfman, J. Phys. Chem., 1956, 80, 826.27 R. F. Firestone, J. Amer. Chem. SOL, 1956, 78, 3226.28 E. Collinson and A. J. Swallow, Chem. Rev., 1956, 56, 471.E. J. Bourne, M. Stacey, and G. Vaughan, Chem. and Ind., 1956, 1372.so P. J. Berry, S, Lipsky, and M. Burton, Trans. Furuduy Soc., 1956, 52, 31 13s GENERAL AND PHYSICAL CHEMISTRY.solvent molecules before energy transfer to the scintillator can occur, butthe participation of ionic species cannot be ruled out.The resistance ofpolyphenyls to radiation has led to their consideration as pile moderatorsand coolants. With this in view Colichman and Gercke31 have subjecteddiphenyl, o-, m-, and fi-terphenyls, fi-quaterphenyl, and various mixtures ofthese to electron and pile radiation over the range 30-350". Yields ofgases (SO--SOO/d hydrogen) of 0 ~ 0 0 1 4 ~ 0 1 molecule per 100 ev were observed.Polymers are also produced.D e w h u r ~ t , ~ ~ using vapour-phase chromatography, has found a multi-plicity of products from the irradiation of n-hexane with 800 kv X-rays.Sixteen hydrocarbons from C , to C,, were detected.In contrast, cyclo-hexane gave only three. Schuler 33 finds the yields of hydrogen from irradi-ated liquid cyclohexane and benzene to decrease only slightly when 0 . 2 ~ -iodine is present, indicating that, as mentioned above for ethane, it must beformed as molecules rather than atoms. The acetylene yield from benzenebehaves similarly. In the presence of oxygen, irradiated heptane, 2-methyl-heptane, cyclohexane, toluene, and benzene give peroxy-compounds (RO),,RO,H, and H,O, (100 ev yields 1--2), carbonyl compounds (yields 0.6-2),and acids (yields 0-2-0.6).34 The yields of a variety of products from X -irradiated acetic acid in oxygen have also been measured.35Liquid ethyl iodide and n- and iso-propyl iodide with 120 kvp X-raysgive mainly iodine and hydrocarbons with the same number of carbon atomsas the parent,36 but these do not seem to originate from thermal radicals.The use of radio-iodine reveals that such radicals as are formed originatealmost entirely from the rupture of the C-I bond.The liberation of halogenby 6OCo y-radiation from CCI,, CBr,, C,CI,, and C&I, has also been in-vestigated ., '' T o y-radiation induces 38 the reactions C6H, + NH, + C,H,*NH2(yields up to 0.36) and C&6 + cc1,-+ C,H,*CCl, (yield 0.45). Otherradiation-induced reactions examined are the bromination of toluene byN-bromosuccinimide 39 and the oxidation of various alcohols by CCl, togive HCI, CHCI,, and aldehyde.40 These are chain reactions and in thelatter 100 ev yields as high as 1800 are observed.Radiation-induced polymerisation has received further attention.Callinan4l compared the physical properties of a variety of polymersprepared by radiation and by conventional initiators.The intensity depen-dencies for the radiation polymerisation of liquid vinyl chloride 42 andacrylonitrile (liquid and solutions) 43 are similar to those given by other31 E. L. Colichman and R. H. J. Gercke, NucZeonics, 1956, 14, No. 7, p. 50.s2 H. A. Dewhurst, J . Chem. Phys., 1956, 24, 1254.35 R. H. Schuler, J . Phys. Chem., 1956, 60, 381.34 N. A. Bach, ref. 5, p. 145; N. A. Bach and N. I. Popov, ibid., p. 156.56 N. A. Bach and V. V. Saraeva, ibid., p. 175.36 R. H. Schuler and R. C . Petry, J. Amer. Chem. SOC., 1956, 78, 3954.37 A.V. Zimin and 2. S. Egorova, ref. 5, p. 249.5 8 A4. V. Zimin, S. V. Churmanteev, and A. D. Verina, ref. 5, p. 249.so R. A. Cox and A. J. Swallow, Chem. and Ind., 1956, 1277.4O K. Hannerz, Research, 1956, 9, sl.'1 T. D. Callinan, J . Electrochem. Soc., 1956, 103, 292.45 R, Bensasson and A. PrCvot-Bernas, ibid., p. 93.A. Chapiro, J . Chim. phys., 1966, 53, 35KINETICS OF CHEMICAL CH-ANGE. 39methods of initiation. This argues against any localisation of the radicalsconcerned in the kinetic chain, Le., growing polymer radicals, but does notreveal anything about the spatial distribution of the initiating radicalsproduced by the radiation. A similar comparison of polymerisation rateshas given primary radical yields for the irradiationu of styrene[G(radicals) = 2 2 - 4 1 and methyl methacrylate (28-54) which, relatively,are in agreement with previous determinations.However, absolute valuesmuch lower than these are also reported.45 The formation of graft polymersoccurs when a polymer solution containing a different monomer isirradiated.@ Diphenylpicrylhydrazyl (DPPH) will also attach itself topolymer chains in similar conditions, but the interesting observation ismade that it does not react at the site of the free radical.46 This is con-cluded from the fact that the product still shows the oxidation-reductioncolour changes associated with free diphenylpicrylhydrazyl. The formationof graft copolymers by using ultrasonic radiation is also rep~rted.~'By an extension of Samuel and Magee'smodel, Ganguly and Magee 48 estimated theoretically the extent of primaryradical combination and primary radical-scavenger reactions occurring inwater with electrons, protons, and a-particles of various energies. Coulson 49has discussed the relative stabilities of H2+ and HO+, which have beensuggested as intermediates in irradiated water, and concludes that the latterwould react readily as HO" + H,O ---t HO + H20+.Weiss 50 suggeststhat the equilibrium HO + H,O+ + H20 + H20+ may be responsiblefor the pHdependence of radiation-induced reactions in water and thatH20+ + HO + H,02+- --t H202 -t H+ is a possible source of hydrogenperoxide.Hochanadel and Lind2 have chosen values of primary yields (Gw)for 0.8N-sulphuric acid and for solutions from 0 .0 1 ~ to neutral whichthey consider most representative at present. In 0.8N-sulphuric acid theypropose : &(H) = 3.70, Gw(0H) = 2.90, Gw(H20,) = 0.80, Gw(H2) = 0.4p.By use of these values and G(Fe3+) 7= 15.6 for aerated ferrous solutions in043N-sulphuric acid, a new determination 51 G(Fe3+) = 8.24 for de-aeratedsolutions now gives a quantitatively consistent picture of the oxidation ofFez+, provided that oxidation of Fe2+ by H (possibly as H,+, but see ref. 150)occurs in de-aerated solutions. A value of Gw(H) + Gw(OH) = 6.12 hasbeen obtained 52 from a comparison of the y- and ultraviolet-initiated chainoxidation of formic acid by hydrogen peroxide, and 6 rfr 0.4 is given 53by a new assessment of previous observations on the y- and ultraviolet-initiated chain decomposition of hydrogen peroxide.By measuring Gw(Fe3+)Water aizd aqueous solzitions.44 D. S. Ballantine, A. Glines, D. J. Metz, J . Behr, R. €3. Mesrobian, and A. J.4 5 T. S. Nikitina and K. S. Bagdasaryan, ref. 5, p. 183.46 A. Henglein and M. Boysen, Mukromol. Chem., 1956, 20, 83.4 7 A. Henglein, ibid., 1956, 18/19, 37.4 8 A. K. Ganguly and J. L. Magee, J . Chem. Phys., 1956, 25, 129.49 C. A. Coulson, J., 1956, 778.50 J. Weiss, Experiextia, 1956, 12, 280.5 1 N. F. Barr and C. G. King, J. Amer. Chem. SOC., 1956, 78, 303.s2 J. L. Weeks and M. S. Matheson, ibid., p. 1273.55 F. S. Dainton, ibid., p. 1278.Restaino, J. Polymer Sci., 1956, 19, 21940 GENERAL AND PHYSICAL CHEMISTRY.in aerated Fe2+ and Fe2+-Cu2+ solutions, Hart et aL8 have determined thenumber of water molecules decomposed for the loss of 100 ev by deuteronswith energies of 3-21 Mev and by protons of 0.3-2 MeV.G(H,O) = 3-5for 21 Mev deuterons which lose 100 ev in 224 A, and only decreases to 3.0for 0.5 Mev protons for which the energy is concentrated in 20 A. Donaldsonand Miller have used the Fe2+ + Cu2+ system with and without air toobtain primary yields for polonium a-particles. In the absence of air anappreciable yield of oxygen is found which is considered to originate fromHO, formed by the intra-track reaction HO + H,O, ---+ HO, + H20.The yields G ( H ) = 0.77 ; Gw(H0,) = 0.25 ; Gw (HO) + Gw(H,02) = 3.12 ;and &(H,) = 1-55 are obtained and the last is found to decrease at highCu2+ concentrations owing to the competition between Cu2+ + H andH + H in the track.Ebert et aZ.55 have extended their observations on hydrogen peroxideformation in oxygenated water by fast neutrons and Ghormley56 hasinvestigated the effect of the pulse frequency of 1.5 Mv electrons on thesteady-rate concentration of hydrogen peroxide formed in water.The latterexperiments suggest an intermediate with a lifetime of sec. in theseconditions. Steady-state concentrations of hydrogen and hydrogen peroxideattained in oxygenated water by 65 kv X-rays and %o y-radiation havebeen measured 57 and in general agree with previous observations.LeBail and Sutton 58 find that G(Fe3+) in y-irradiated Fe2+-H,SO,solutions is unaffected by oxygen pressures up to 14 atm.and by acid con-centrations up to 5 ~ , which further emphasises the anomaly of the highyields (up to 60) obtained by Proskurnin et aZ.59 G(Fe3+) is found by Trum-bore and Aten 6O to increase from 15.5 to 18.6 in going from H,O to D,Osolutions, which is more than the 12% reported by McDonell,61 who alsofinds 62 an increase in the rate of the y-initiated hydrogen peroxide decom-position in D,O. It seems probable that these differences originate fromthe different diffusion and recombination rates of the primary radicalsformed.It has been established by using tracers that the exchanges CrlI1-Crmand Tlm-TP are induced by y-radiation 63 and X-radiation respectively.In the thallium system T12+ is suggested as an intermediate. Sworski 66also invokes the formation of T12+ to explain the increase in G(Ce3+) to 7.9when Ce4+ solutions are irradiated with Tl+, compared with 2.39 withoutT1+.In this study it is also found, contrary to a previous report, that Ce3+decreases G(Ce3+) from 2-39 and this is attributed to the reaction54 D. M. Donaldson and N. MilIer, Trans. Faraday Soc., 1956, 52, 652.5 5 M. Ebert, P. Howard-Flanders, and D. Moore, Radiation Res., 1956, 4, 110.56 J. A. Ghormley, ibid., 1956, 5, 247.5 7 P. I. Dolin, ref. 5, p. 7.6 B H. LeBail and J. Sutton, J . Chim. $hys., 1956, 53, 430.6* M. A. Proskurnin, V. D. Orekhov, and E. V. Barelko, ref. 4, p. 41; M. A. Pros-61 W. R. McDonell, USAEC Report ANL5206.63 M. Lefort and M. Lederer, Corn@. rend., 1956, 242, 2458.64 G.E. Challenger and B. J. Masters, J . Amer. Chem. SOC., 1956, 78, 3012.6 5 T. J. Sworski, Radiation Res., 1956, 4, 483.kurnin, V. D. Orekhov, and A. I. Chernova, ref. 5, p. 79.C. N. Trumbore and A. H. W. Aten, J . Amer. Chem. SOC., 1956, 78, 479.Idem, ibid., Report ANL-5207KINETICS OF CHEMICAL CHANGE. 41Ce3+ + HO + Ce4+ + OH occurring in the tracks at the expense ofHO + HO -+ H,O,. Values of G(Ce3+) in CeSf + Cer+ + H2S04 +HCO,H solutions suggest that the reaction HO + H2S04 ---t H20 +HSO, occurs to a significant extent.Further work is reported on the irradiation of solutions of nitrite andnitrate,g7s 68 ferrous and ferric trisphenanthrolines and dipyridyl~,~~ andhydrazine. 70There has been much work on the radiation-induced oxidation of organiccompounds in oxygenated aqueous solution.Ethylene gives mainlyacetaldehyde and, at high pressures (ca. 45 atm.), yields up to 200 areobtained.71 A further examination of benzene solutions 72 confirms thatphenol is the major product (yield 2.2). A small amount of aldehyde isalso formed which appears to be mucondialdehyde, a product which couldresult from oxidative ring opening. In the presence of Fe2+ the phenolyield increases 73 to 6.0, no doubt owing to the utilisation of the hydrogenperoxide which is also produced. Solutions of butyl and benzyl alcoholsgive aldehydes and hydrogen peroxide T4 with a yield of 3.1. With ethanoland pyruvic acid Johnson et aL75 observed yields of aldehyde and lactic acidrespectively which rise as high as 7.0 as the concentration of substrateincreases to 1 .0 ~ . They point out that this is higher than would be expectedif HO alone were the oxidant since G(H0) = 3-35 Ascorbic acid inaerated solutions is found to be oxidised according to the reactionAH, + 0, + A + H20,, and a high oxidation yield of 7.8 is also reportedhere.5l This is accounted for by assuming that HO, also behaves as anoxidant. On the other hand, the high values of G(NH3) and G(g1yoxylicacid) given by the oxidative deamination of 0.5-%O~-glycine in aeratedsolutions 76 are attributed to direct action, possibly by " sub-excitation "electrons. The very high yields of sulphur (>lo3) from thiourea 77 nodoubt arise from a chain reaction. Secondary amines in solution giveprimary amine and aldehyde and it is suggested that the mechanismHO 0, Ha0R-NHCH~R - R-NH~HR RN:CHR - R.NH, + RCHOmay also account for cleavage and post-irradiation effects found withpeptides.78In de-aerated solutions an interesting difference between the effects ofcyclotron-produced helium ions and X-rays on aqueous glycine is observed.The helium ions give amino-derivatives of succinic acid 79 not found with68 T. J. Sworski, J . Amer. Chem. SOC., 1956, 78, 1768.67 V. D. Orekhov, A. I. Chernova, and M. A. Proskurnin, ref. 5, p. 91.6 8 N. A. Bach, ref. 4, p. 23.'O M. Lefort and M. Haissinsky, ibid., p. 527.71 E. J. Henley, W. P. Schiffries, and N. F. Barr, Amer. Inst. Chem. Eng. J., 1956,72 M. Daniels, G. Scholes, and J. Weiss, J . , 1956, 832.73 M.A. Proskurnin and E. V. Barelko, ref. 5, p. 99.74 M. A. Proskurnin, E. V. Barelko, and L. V. Abramova, ref. 5, p. 106.75 G. R. A. Johnson, G. Scholes, and J. ?Veiss, Nature, 1956, 177, 883.76 W. M. Garrison and B. M. Weeks, J . Chem. Phys., 1956, 25, 585.77 W. M. Dale, Nature, 1956, 177, 531.76 M. E. Jayko and W. M. Garrison, J . Chem. Phys., 1956, 25, 1084.J. Pucheault, J . Chirn. phys., 1956, 55, 697.2, 211.W. M. Gamson and B. M. Weeks. ibid., 1956, 24, 61642 GENEKAL AND PHYSICAL CHEMISTRY.X-rays, which is a consequence of the high radical concentrations in theformer case.The kinetics of y-initiated polyinerisation of acrylonitrile in aqueoussolution have been reinvestigated. The rate depends on (Intensity)Q85and it is concluded 8o that, since other methods of initiation give about thesame value of the exponent, the previous explanation of the high exponentin terms of a non-uniform distribution of the radicals is erroneous.Appre-ciable degradation of polymethacrylic acid by X-rays in aqueous solutionoccurs even in the absence of air.81 A parallel kinetic study of the break-down by HO produced from photolysed hydrogen peroxide supports thecontention that HO is responsible in the X-irradiation and not HO, aspreviously reported. These conclusions have been questioned. 82 Oxidativeand hydrolytic degradation of amylose in solution by y-radiation is foundto be accompanied by the production of small fragments of the molecule andof acidic group^.^The presence of glucose enhances the reversible reduction of aqueousmethylene-blue by y-radiation and the decomposition of low concen-trations of chloral hydrate by 200 kv X - r a d i a t i ~ n .~ ~ These effects areprobably due to the reactions of the radicals produced from glucose by Hand HO. Radicals produced in this way from a variety of organic com-pounds have been shown 86 to reduce Fe3+, Cu2+, and quinones, and whenboth H and HO give rise to a radical the amount of reduction produced is ameasure of Gw(H) + Gw(HO). The kinetic analysis of the metal ion-organiccompound systems, previously carried out by Hart for Fe3+ in formic acid,has enabled relative values for the rates of hydrogen abstraction by hydro-gen atoms for a number of substances to be determined.86In the biochemical field Butler has discussed the effects of radiation onimportant biological materials, in particular deoxyribonucleic acid (DNA),and reviewed the theories of radio-biological action.*' Further work onDNA suggests that breaks or weak points are produced in the single nucleo-tide strands. 88 Purine and pyrimidine ribonucleotides give hydroperoxidesin air and form labile phosphate esters, which release inorganic phosphateafter irradiation has ceased.89 High doses are usually required to produceobservable changes in DNA but Cole and Ellis observed that a dose of850 R given to deoxyribonucleoprotein produces a marked increase in theliberation of DNA by trypsin as well as a considerable decrease in swellingcapacity in water.Russian work on DNA and various proteins has alsobeen rep~rted.~l In work on biological iron compounds in solution Barron8O R.Benasson and A. Prkvot-Bernas, J . Chim. phys., 1956, 53, 93.81 J. H. Baxendale and J. K. Thomas, Chem. and Ind., 1956, 377.8a P. Alexander and M. Fox, ibid., p. 1387.8s E. J. Bourne, M. Stacey, and G. Vaughan, ibid., p. 573.a6 A. Hilsenrod, J . Chem. PhJls., 1956, 24, 917.86 J . H. Baxendale and D. Smithies, 2. phys. Chem. (Frankfurt), 1956, 7, 242.J. A. V. Butler, Radiation Res., 1956, 4, 20.08 K. V. Shooter, R. H. Pain,and J. A.V. Butler, Biochim. Bioph-ys. Acta, 1956,20,497.M. Daniels, G. Scholes, and J . Weiss, J . , 1956, 3771.DO L. J. Cole and M. E. Ellis, Rudiafion Res., 1956, 5, 252.91 A. M. Kusin,'Session Acad.Sci., U.S.S.R., on Peaceful Uses of Atomic Energy,V. D. Orekhov, A. I. Chernova, and &I. A. Proskurnin, ref. 5, p. 85.July, 1955 ; Meetings of Biology Division, p. 69; A. G . Passynsky, ibid., p. 104KINETICS OF CHEMICAL CHANGE. 43and Johnson 92 find that the FeII compounds oxyhzmoglobin and myoglobinare oxidised and the FeIII coinpounds hemoglobin, hzemin, cyanide haemo-chromogen, and cytochrome c are reduced. In all cases the porphyrin ringis destroyed. Indirect reduction of cytochrome c by the free radicalsproduced in the irradiation of solutions of ethanol, methanol, and hydrogenis found to give a product different from that of enzyme reduction, butbenzoate or succinate solutions yield the identical product.93 The change inthe catalase activity of irradiated yeast after irradiation has been investig-ated.g4Ghormley et d g 5 9 96 have extended previous observations onirradiated ice at low temperatures. Oxygenated ice gives hydrogen andhydrogen peroxide even at -200".There is evidence for the release of aspecies which decomposes hydrogen peroxide when irradiated ice is warmedto -180" and of another which has an absorption peak at 2800 tf. Thebehaviour of these entities with temperature is paralleled by that of para-magnetic resonance peaks attributed to H and HO respectively, and alsoby certain features of the luminescence which appears when ice warms afterirradiation at - 196".96 Paramagnetic resonance has been used to identifythe ions and radicals formed in the irradiation of a wide variety of com-pounds at -196" including alcohols, amines, amides, t h i ~ l s , ~ ' and alkyls oftin, zinc, and mercury.98 Electron-irradiated solid ferrous ammoniumsulphate gives sulphite, hydrogen, and Fe3+ when dissolved in water.Thehydrogen appears to arise as a result of reaction of the irradiated salt withthe water since anhydrous ferrous sulphate gives the same yield.99 A moredetailed account of the polymerisation of solid acrylamide by y-radiationhas been given.lm The reaction rate is of the first order in dose rate andthe polymer molecular weight independent of it, which suggests that thepolymerisation occurs in localised regions. Other solid monomers whichpolymerise are methacrylamide, methylenebisacrylamide, vinylcarbazole,vinyl stearate, methacrylic acid, and acrylic acid and its K, Ca, and Basalts.lm The polymerisation of hexamethylcydotrisiloxane to a substanceinsoluble in benzene occurs on irradiation with 800 kvp electrons.lO1 This isnot the usual type of polymerisation but rather resembles the formation ofhigh-molecular weight material from solid hydrocarbons.The subjecthas been reviewed by Charlesby lo2 and Russian work has been describedby Karpov.lm Chapiro lo4 has investigated the changes in colour andSolids.The irradiation of polymers continues to be an active field.** E.S . G. Barron and P. Johnson, Radiation Res., 1956, 5, 290.9s L. K. Mee and G. Stein, Biochem. J . , 1956, 62, 377.9' D. L. Aronson, M. J. Fraser, and C . L.Smith, Radiation Kes., 1956, 5, 225.95 J. A. Ghormley and A. C. Stewart, J . Amer. Chem. SOC., 1956, 78, 2934.9 6 J. A. Ghormley, J . Chem. Phys., 1956, 24, 1111.9 7 C. F. Luck and W. Gordy, J . Amer. Chem. SOC., 1956, 78, 3240.98 W. Gordy and C. G. McCormick, ibid., p. 3243.loo A. J. Restaino, R. B. Mesrobian, H. Morawetz, D. S. Ballantine, G. J. Dienes,lol E. J. Lawton, \V. T. Grubb, and J . S. Balwit, J . Polymer Sci., 1956, 19, 455lo* A. Charlesby, Nucleonics, 1956, 14, No. 9, p. 82.los V. L. Karpov, ref. 4, p. 1.lo' A . Chapiro, 3, Chim. phys., 1956, 58, 293, 295, 306.E. R. Johnson, ibid., p. 5196.and D. J. Metz, ibid., p. 293944 GENERAL AND PHYSICAL CHEMISTRY.softening points of poly(rnethy1 methacrylate) and cellulose acetate whenirradiated and finds prolonged post-irradiation effects. He considers thatthe primary reaction with these and with other polymers is the simultaneousbreaking of several C-C bonds, as occurs in mass-spectrometric observationson larger molecules.The changes in physical properties of a wide varietyof polymers after irradiation have been examined by Harrington,lo5 andFowler loti has given a theoretical treatment of the conductivity induced ininsulators such as amber, mica, and plastics. A clear picture of the processeswhich lead to cross-linking, hydrogen formation, and double-bond formationin polyethylene and related substances has not yet emerged, but recent workshows some advances. Several workers lO3*lo7 report a decrease in theextent of the crystalline phase in polyethylene on irradiation, an effectwhich is also observed with low-pressure polyethylene.lO* It is now estab-lished lo7, lo9 that the unsaturation which is produced is entirely trans-vinylene, and moreover these groups are also formed with about the sameyield in polymethylene and octacosane, so that branching in the moleculedoes not affect this process.lOg However, branching is responsible for almostall the gaseous hydrocarbon given by polyethylene.Miller et aLfW concludethat main-chain breaking is absent in unbranched molecules except at theends, that unsaturation- results from the ejection of molecular hydrogen,and that cross-linking occurs by combination between radicals on adjacentchains, these being formed by ejection or abstraction of hydrogen.On theother hand, Pearson 110 suggests that addition of polymer radicals to thedouble bonds formed is responsible for cross-linking. From the effect ofoxygen on gel formation, Alexander and Toms ll1 conclude that cross-linking and chain breaking are not alternative processes and that in thepresence of oxygen there is one break for each cross-link. Okamoto andIsihara 112 have used kinetic analysis to derive relationships between theextents of the various processes.Photochemistry. Work in which photochemical methods have been usedmainly to study the kinetics of gas phase reactions is dealt with under“ Kinetics of Gas Reactions.”It appears that after a run of 26 years aqueous uranyl oxalate is likelyto be replaced by ferrioxalate solution as a general purpose actinometerliquid.In addition to higher sensitivity and greater convenience, ferri-oxalate can be used further into the visible region, and as a result of athorough investigation by Hatchard and Parker values of quantumyields are now available from 509 mp to 254 mp. For special purposes, e.g.,intensity determinations in light of mixed wavelengths, uranyl oxalate isstill useful, and a method of analysis leading to increased accuracy has been105 R. H. Harrington, Nucleonics, 1956, 14, No. 9, p. 70.106 J. F. Fowler, Proc. Roy. SOC., 1956, A , 236, 464.lo’ A. Brockes and R. Kaiser, Nuturwiss., 1956, 48, 53.108 R. Kaiser, Kolloid Z., 1956, 148, 168.109 A. A. Miller, E. J. Lawton, and J. S. Balwit, J .Phys. Ckem., 1956, 60.l10 R. W. Pearson, Chsm. and Ind., 1956, 903.111 P. Alexander and D. Toms, J . Polymer Sci., 1956, 23, 343.112 H. Okamoto and A. Isihara, ibid., 1956, 20, 115.n* C. G. Hatchard and C. A. Parker, Proc. Roy. Soc., 1956, A , 235, 618,599KINETICS OF CHEMICAL CHANCE. 45described.l14 Further progress with light in the far ultraviolet region ismade possible by the development of a sapphire-tube discharge lamp 115with an output of 2 x 1019 quantalsec. in the 1540A region, and by theuse of synthetic BaF, crystals 1l6 which transmit down to 1345 A.Wijnen 117 has photolysed ethane at 1470 A and observed the formationof H,, CH,, C,H,, and C,H,,. The primary reaction is considered to beC,H, + hv --t C,H, + H which may be followed by H + C,H, +C2H6* ---t ZCH,.Further work on photo-ionisation round 1236 A showsthat with nitric oxide 118 dissociative recombination NOf + e + N + 0is important. Other reported photolyses in the gas phase are : CH20 +hv + H + HCO, which is effective at 3650 A and puts a lower limitof 78 kcal. on the C-H bond strength ; 119 CH,*CH:CO + hv + CH,*CH +CO ; l2* cyclooctatetraene + hv + C,H2 + C,H, + polymer; 121 and adetailed investigation of methyl iodide,12, which confirms that " hot ''methyl radicals are responsible for formation of CH, and some C2H6. Noyeset aE.1Z3 have reviewed the photochemistry of ketones with particular refer-ence to the primary act, and in the case of 3-chloro- and 4-chloro-butan-2-ones Taylor and Blacet l Z 4 find evidence that the major reactions areCH,CO*CHCl-CH, + hv __t CH,*CO*CH*CH, + Cl and CH3*COCH2*CH,C1 + hv __c CH,CO + CH,*CH,Cl respectively.The same workers alsoinvestigated 125 the photochemical oxidation of diacetyl by oxygen in whichthe main products are CO, CO,, CH,O, and H,O. Ozone formation fromilluminated NO,-O,-hydrocarbon mixtures has been followed 126 by infraredabsorption in a cell with path-length 430 m. in an attack on the problem ofatmospheric " smog " formation. Volman has analysed previous workon the production of ozone from oxygen and concludes that absorption abovethe convergence limit (1750 A) to give the state of oxygen is followedby dissociation to two 3P atoms as suggested earlier by Flory. In support ofthis, it is found las that the kinetics of H202, H,O, and 0, formation in H2-02mixtures at 1849 A agree with those obtained below the convergence limit.The applications of flash photolysis have been reviewed lZ9 and thetechnique has been used to show the existence of transient species in tetra-ethyl-lead vapour, irradiated aqueous amino-acids, 131 and halide11* G.T. Rogers, Chem. and Ind., 1956, 572.115 L. S. Nelson, J . Opt. SOC. Amer., 1956, 46, 768; L. S. Nelson and D. A. Ramsay,116 T. A. Chubb, J . Opt. SOC. Amer., 1956, 48, 362.117 M. H. J. Wijnen, J . Chem. Phys., 1956, 24, 851.11* M. Zelikoff and L. M. Aschenbrand, ibid., 1956, 25, 674.llS R. Klein and L. J. Schoen, ibid., 1956, 24, 1094.lZo G. B. Kistiakowsky and B. H. Mahan, ibid., p. 922.121 I<.Yamazaki and S. Shida, J . Chem. SOC. Japan, 1956, 77, 500.la2 R. D. Souffie, R. R. Williams, and W. H. Hamill, J . A w v . Ckem. Sot., 1956, 78,lZ3 W. A. Noyes, G. B. Porter, and J. E. Jolley, Cizern. Rev., 1956, MI, 49.lZ1 R. P. Taylor and F. E. Blacet, J . Amer. Chem. SOC., 1966, 78, 706.lZ5 Idem, I d . Eng. Chem., 1956, 48, 1505.12u E. R. Stephens, P. L. Hanst, R. C. Doerr, and W. E. Scott, ibid., p. 1498.lZ7 D. H. Volman. J . Chem. Phys., 1956, 24, 122.128 Idem, ibid., 1966, 25, 288.129 R. G. W. Norrish and B. A. Thrush, Quizrt. Rev., 1956,10, 149.lSo C. L. Cook and J. G. Clouston, Nature, 1956, 177, 1178.131 L. I. Grossweiner, J . Chew. Ph3fs., 1956, 24, 1255.J . Chem. Phys., 1956, %* 372.91746 GENERAL AND PHYSICAL CHEMISTRY.solutions,132 the formation of N, from NH,, and to obtain the spectrumof the radical HCO produced from acetaldehyde. 134In the liquid phase Fillet et ~ ~ 1 .l ~ ~ find that the photochemical oxidationof acetaldehyde to peracetic acid is a chain reaction with a mechanismanalogous to that established for the peroxidation of ethylenic compounds.The decomposition of chromyl chloride to CrO, and C1, in carbon tetra-chloride with 4190 light is also a chain reaction 136 with quantum yields102-103. The proposed primary step is CrO,Cl, + hv --F CrO,C,l + C1.The phenomenon of energy transfer from solvent to solute has been examinedfor irradiated solutions of P-terphenyl in toluene by Cohen and 1Veinreb.l3'They conclude that the transfer must take ca.lOu9 sec., i.e., there is somedelay. They also show that, even in dilute systems, energy is not exchangedbetween solvent molecules before transfer occurs. The transfer from p-terphenyl to other fluorescent compounds in toluene and dioxan-watersolutions has been examined by Gemmill.138 Terenin and Ermolaev 139have continued their studies of this in ethanol-ether glasses at -195", andshow that it is possible to transfer energy from a variety of donors whichabsorb the radiation, such as aromatic aldehydes and ketones, to a varietyof acceptors such as naphthalene, diphenyl, etc. However this is onlypossible when the triplet level of the donor is above that for the acceptor inaccordance with the general thesis that triplet states are the ones concernedin the transfer.Other studies on glasses include an investigation of the colour formationin irradiated spiro-pyran and dianthrane derivatives, 140 and a search forthe products of photolysis of tetramethyltetrazen, sulphur chlorides, bromal,bromopicrin, acetophenone, and dipheny1rner~ury.l~~ The last two, althoughshowing appreciable photolysis in the liquid, are stable in the glass a t 77" K.In aqueous solution reactions induced by the photolysis of hydrogenperoxide have been studied.Burton and Dewhurst compared thekinetics of oxidation of hydrazine induced by photolysed hydrogen peroxidewith the oxidation by ionising radiation studied earlier. Nitrogen, ammonia,and oxygen are produced and a reaction is suggested in which the primarystep H,O, + hv + 2H0 is followed by HO + N,H,+ ---t N,H4+ + H,Oand subsequent reactions of N,H4+ (or N,H,).The alternative primarystep H,O, + hv + H,O + 0 was also considered and rejected. Theprimary quantum yield for photolysis of hydrogen peroxide at 2537 A hasbeen redetermined by Weeks and Matheson 52 using the induced oxidationof formic acid by photolysed hydrogen peroxide in the presence of oxygen.The mechanism proposed by Hart is H,O, + hv ---t 2HO; HO + H*CO,H132 L. I. Grossweiner and M. S. Matheson, J . Chem. Phys., 1956, 23, 2443.133 B. A. Thrush, Proc. Roy. Soc., 1956, A , 235, 143.134 G. Herzberg and D. A. Ramsay, ibid., p. 34.135 P. Fillet, M. Niclause, and M. Letort, J . Chzm. phys., 1956, 53, 8.138 G.-M. Schwab and S. Prakash, 2.Phys. Chem. (Frankfurt), 1956, 6, 387.197 S. G. Cohen and A. Weinreb, Proc. Phys. Soc., 1966, B, 69, 593.138 C. L. Gemmill, Rudiaiio~ Res., 1956, 5, 216.139 A. Terenin and V. Ermolaev, Trans. Faraduy SOC., 1966, 53, 1042.140 Y. Hirshberg, J . -4mer. Chenz. SOC., 1956, 78, 2304.111 K. G. Sowden and N. Davidson, ibid., p. 1291.l42 AT. Burton and H. A. Dewhurst, 2. phj's. Chenz. (Fva7thf7411), 1956, 7, 27KINETICS OF CHEMICAL CHANGE. 47+ H20 + CO2H ; C0,H + H2Og + CO, 4- H2O -+- HO; CO2H -+0, ---t CO, + HO, ; 2H0, ----t H,O, + O,, so that the quantum yield forabsorption of oxygen is the primary yield for photolysis of hydrogen per-oxide. The kinetics are consistent with this scheme and the primaryquantum yield 0.49 is obtained. This agrees with another determination byuse of other aliphatic acids in the absence of oxygen.81 Here it is foundthat the quantum yield for photolysis of peroxide in conditions where thechain reaction is absent is 1-00 at 25" c, but falls to 0.50 in the presence ofaliphatic acids.This is interpreted to mean that the reaction HO +H,O, _.t HO, + H,O, which normally follows the primary step, is replacedby HO + CH,*CO,H --+ H,O + CH,*CO,H and that the radical CH,*CO,Hdoes not, as is the case with formic acid, take part in a chain reaction.Neither of these studies, however, eliminates the possibility of H,O, + hw +H,O + 0 as the primary step, but they do preclude the possibility thatoxygen atoms, if formed, combine to give 0,. Previous work on the ultra-violet-induced oxidation of Fe2 + in aqueous solution had indicated that thereaction Fez+ + H,+ _t Fe3+ + H, was important since the quantumyields were pH-dependent.However a re-investigation has shown thatinitiaZ yields are independent of pH and the alternative reaction Fe2+ + H +H,O+ FeOH2+ + H, is suggested. ofalcohols by oxygen photosensitised by sodium anthraquinone-2-sulphonateindicates that the excited quinone molecule reacts A* + R-CH,*OHAH + R-CH*OH. It is pointed out by Bowen 145 that this parallels pre-vious work with dichromate instead of quinone and suggests that here, too,hydrogen-abstraction occurs. The cross-linking of Polythene photosensitisedby benzophenone and diphenylamine observed by Oster 146 probably alsoinvolves a similar reaction, although cross-linking also occurs in the absenceof photosensitiser. Photosensitised oxidation-reductions induced by chloro-phyll-type compounds 147 and by fluorescein and its halogen derivatives 148are also reported.In the latter there is evidence from quenching experi-ments for a long-lived excited state. High-molecular weight copolymers ofally1 alcohol and acrylonitrile have been prepared by photopolymerisationsensitised by acriflavin and ascorbic acid,149 and the kinetics of polymeris-ation of styrene, initiated by the absorption of 4600 A light by Neutral-redand triphenylmethane-type dyes, have been obtained ; 150 the latter seemto act by energy transfer, but with the former it appears that radicals areproduced on illumination.Polymerisation.-Radical Po1ymerisations.-General.The effect of devi-ations from ideality on the molecular-weight distribution in linear poly-merisations has been considered. The classical network theory of gelationA study of the oxidationIra M. Lefort and P. Daizon, J . Chim. phys., 1956, 53, 536.144 C. F. Wells, Nature, 1956, 177, 482.L45 E. J. Rowen, ibid., p. 889.146 G. Oster, J . Polymer Sci., 1956, 22, 185.lr7 R. Livingston and R. Pariser, J . Amer. Chew. SOC., 1956, 78, 2944, 2948; R.118 A. H. Adelman and G. Oster, ibid., pp. 913, 3977.I5O H. Miyama, J . Chem. SOC. Japan, 1955, 76, 1013, 1361.Livingston and K. E. Owens, ibid., p. 3301.G. Oster and Y . Mizutani, J . Polymer Sci., 1956, 22, 173.F. E. Harris, J . Polymer Sci., 1955.18, 36148 GENERAL AND PHYSICAL CHEMISTRY.has been verified for a model unsaturated polyester cross-polymerisation.2The addition of a cross-linking agent to a very dilute solution of a susceptiblepolymer produces intramolecular cross-linking with the formation of rings.The probability of forming rings of various sizes, given one crosslink permolecule, has been dis~ussed.~ The hydrogen bonding which causes thedimerisation of carboxylic acids in solution also leads to the formation ofinter- and intra-molecular aggregates in polymers containing carboxylgro~ps.~ A thermistor method for the determination of velocity coefficientsin vinyl polymerisations has been developed and applied to reactions inhighly viscous media. The influence of carbons on polymerisation reactionshas been disc~ssed,~ and the presence of free radicals on the surface of carbonblack demonstrated by paramagnetic-resonance measurements.8 The actionof carbon black in stabilising polymeric materials cannot be accounted for bysimple cohesive forces and is probably due to the cross-linking of degradedpolymer radicals by carbon particles.Macromolecular stable free N-poly-radicals have been obtained by the y-irradiation of a number of polymers inthe presence of diphenylpicrylhydrazyl (DPPH) .lo The free radicalsproduced in the polymer combine with the a-N-phenyl nuclei rather thanwith the p-N-radical of DPPH, and subsequent oxidation gives a violetpolymer.Attempts to induce asymmetric radical addition during chain growthby using monomers containing an asymmetric centre close to the doublebond have been unsuccessful in homopolymerisations, l1 but Beredj ick andSchuerch have succeeded in obtaining an optically active copolymer.Thecopolymerisation of (-)-a-methylbenzyl methacrylate with maleic anhydridegives an optically active copolymer containing the asymmetric centresoriginally present in the monomer. When these are removed by reduction,the copolymer remains optically active, but of opposite sign to the unreducedcopolymer. The only apparent explanation is that asymmetry has beeninduced during the process of radical polymerisation. l2The photosensitised polymerisation of acrylonitrile inNN-dimethylformamide has been studied under homogeneous conditions l3at 25' c.The initiator exponent (0.59) found is slightly greater than theapproximate value of 0-5 previously reported,14 and strengthens the evidencefor retardation by chain transfer to the solvent. Constancy of order ismaintained up to at least 70% conversion, but after-effects have beenobserved which are not in conformity with the theoretical expression. WithGeneral kinetics.2 M. Gordon, B. M. Grieveson, and I. D. McBlillan, Trans. Faraday Soc., 1956, 52,3 W. Kuhn and H. Majer, Makromol. Chem., 1956, 18/19, 239.4 Shih-Yen Chang and H. Morawetz, J . Phys. Chem., 1956, 60, 782.5 H. Miyama, Bull. Chem. Soc. Japan, 1956, 29, 711.6 S. Fujii and S. Tanaka, J . Polymer Sci., 1966, 20, 409.9 R. S. Bradley, J . Colloid Sci., 1956. 11, 237.10 A.Henglein and M. Boysen, Makromol. Chem., 1956, 20, 83.11 C. G. Overberger and I,. C. Palmer, J . Amer. Chem. Soc., 1956, 78, 666.l2 N. Beredjick and C. Schuerch, ibid., p. 2646.13 P. F. Onyon, Trans. Faraday Soc., 1956, 62, 80.14 W. M. Thomas, E. H. Gleason, and J. J. Pellon, J . Polymer Sci., 1965, 17, 275.1012.P. Smith, ibid., 1956, 21, 143.M. Szwarc, ibid., 1956, 19, 589KINETICS OF CHEMICAL CHANGE. 49azoisobutyronitrile (AIBN) as catalyst at 60°, ferric chloride acts as anexclusive terminator, the ferric ion being reduced to ferrous.1s The valueof d[Fe2+]/dt gives the rate of initiation, and the rate constant for thedecomposition of AIBN into useful radicals has been determined. The rateof ferric termination depends on the electron-donating properties of thepolymer radicals, and the polymerisation of styrene is strongly inhibited byferric salts.The efficiency of initiation of styrene chains by AIBN has beendetermined in NN-dimethylformamide and in ethyl methyl ketone, and isin good agreement with the results for styrene in benzene obtained byBevington using a tracer technique. Collinson and Dainton have indi-cated the general nature of the redox reaction between organic radicals andmetallic sa1ts.l' The rate of reaction depends on the nature of the metallicion as well as on the polymeric radical,18 and in polymerisation systems inwhich the probability of chain transfer is low the reaction can be used todetermine the number average degree of polymerisation. Rate constantshave been determined for the thermal and photochemical bulk polymeris-ation of methacrylonitrile catalysed by benzoyl peroxide and AIBN.l9A.lthough the polymer comes out of solution as a highly swollen jelly at lowconversions, the rate constants for propagation, termination, and transferare normal. The energies of activation and the temperature-independentfactors, however, are all slightly higher than normal, probably owing to theenmeshing of radicals by the coiled polymer chains.The mechanism of polymerisation in precipitating media is still uncertain.The autocatalytic increase in rate with conversion characteristic of thesesystems has been observed in the y-ray initiated polymerisation of vinylchloride.20 The results can be partly interpreted by the non-stationary-statetreatment proposed by Magat,21 but the problem is complicated by theproduction of initiating radicals from the polymer.The non-stationary-state method has been applied to the bulk polymerisation of acrylonitrile 82based on the long-lived after-eff ects observed in the radiochemical polymer-isati0n.2~~ 249 25 The conventional termination reaction between propagatingradicals is assumed to be prevented by occlusion, leading to a continuedbuild-up in the concentration of these radicals with conversion. Thisapproach has been criticised by Bamford and Jenkins,Zs who show thatgrowing polyacrylonitrile radicals initiated photochemically undergo atermination reaction sufficiently rapid to give stationary-state conditionsat low conversions.The extended period of increase in rate with conversionobserved in both the photochemical and radiochemical polymerisations istherefore unlikely to be due to the gradual accumulation of occluded1 5 C. H. Barnford, A. D. Jenkins, and R. Johnston, Nubuve, 1956, 17'7, 992.16 J . C. Bevington, I'vuns. Furaduy SOC., 1955, 51, 1392.1 7 E. Collinson and F. S. Dainton, A7atura, 1956, 177, 1224.18 E. Collinson, F. S. Dainton, and G. S. McNaughton, J . Chim. phys., 1955, 52, 556.19 N. Grassie and E. Vance, Trans. Favaduv SOC., 1956, 52, 727.2" A. Chapiro, J . Chim. phys., 1956, 53, 512.21 81. Magat, J. Polymer Sci., 1955, 16, 491.24 J. Durup and M. Magat, ibid., 1955, 18, 586.24 I<. Bensasson and A. Prevot-Bernas, J . C h i i ~ .phys., 1956, 53, 93.2 6 A. Prevot-Bernas and J. Sebban-Danon, ibid., p. 418.26 c. €1. Barnford and A. D. Jenkins, J . I'olz'nt~r Sci., 1956, 20, 405.M. Magat, ibid., 1956, 19, 58350 GENERAL AND PHYSICAL CHEMISTRY.radicals. Ham 27 has shown that chain transfer with polymer is probablynegligible, and certainly not sufficient to account for the induction period.The usual stationary-state treatment has been used to derive ratios of kineticconstants in the bulk polymerisation of acrylonitrile 28 by azoisobutyro-nitrite at 25". In contrast to the reaction at 60°, the rate is substantiallyconstant over the range 1-20% conversion, and the results are consistentwith radical termination by disproportionation.Further confirmation of the ceiling-temperature effect has been obtained.29The heat and entropy of polymerisation, and hence the ceiling temperatureof l-enes, is independent of the length of the saturated side-chain, when thiscontains more than one carbon atom.A molecular-orbital theory ofreactivity in radical polymerisation has been presented30 and the effect ofviscosity on polymerisation kinetics examined.31, 32 The onset of diffusioncontrol at high conversion has been studied for the polymerisation of styreneand methyl metha~rylate.~~ The peroxide-catalysed bulk polymerisationof allyl acetate has been re-examined under oxygen-free condition^.^^ Thereaction exhibits the linear relation between. the disappearance of themonomer and the disappearance of peroxide characteristic of allyl polymer-isations, and ascribed to degradative chain transfer.Some induced decom-position of the peroxide occurs in this system, and to a greater degreein the polymerisation of l-methylprop-2-enyl acetate.35 Gaylord hasshown that although degradative chain transfer is the major factorlimiting the molecular weight in allyl polymerisation, effective chaintransfer may also play an important part, and is not excluded by aconstant value of d[monomer] /d[peroxide] .36 In the polymerisation ofl-methylprop-2-enyl propionate, effective chain transfer constitutes92-94% of the total transfer.37 Degradative transfer limits the molecularweight in diallyl polymerisation, but becomes less important beyond the gelpoint.38 There is some evidence that the termination step in the polymer-isation of 2 : 6-dimethylstyrenes is a degradative transfer.39 The use ofNN-dimethylaniline (DMA) as a promoter for the decomposition of peroxideinitiators (see p.50) has led to the investigation of its effect on chainpropagation and termination. The rate of decomposition of azoisobutyro-nitrile is not affected by NN-dimethylaniliiie but the rate of polymerisationof a number of monomers by azoisobutyronitrile is reduced in the presenceof NN-dimethylaniline, which acts as a chain-transfer agent .40 NN-z 7 G. E. Ham, J . Polymer Sci., 1956, 21, 337.28 1'. F. Onyon, ibid., 1956, 22, 19.29 F. S. Dainton, K. J . I ~ i n , and D. R. Sheard, Tvans. Faraday SOC., 1956, 52, 414.80 K. Hayashi, T. Yonezawa, C.Nagata, S. Okamura, and I<. Fukui, J . Polymer31 H. W. Melville, 2. Elektrochem., 1956, 60, 276.32 A. N. Pravednikov, Doklady Akad. Nauk S.S.S.U., 19.56, 108, 495.33 E. R. Robertson, Trans. Faraduy Soc., 1956, 52, 426.34 M. Litt, Diss. Abs., 1956, 16, 1218.35 N. G. Gaylord and F. M. Kujawa, J. Polymer Sci., 1956, 21, 327.36 N. G. Gaylord, ibid., 1956, 22, 71.37 N. G. Gaylord and F. M. Kujawa, zbid., 1956, 21, 329.3 8 H. W. Starkweather and F. R. Eirich, Ind. Eng. Chem., 1965, 47, 2452.39 M. J . Schlatter, J. Amer. Chew%. Soc., 1956, 78, 3440.40 M. Imoto, T. Otsu, T. Ota, H. Takatsugi, and M. Matsuda, J. Polymer Sci., 1966,SCL., 1956, 20, 537.22, 137KINETICS OF CHEMICAL CHANGE. 51Dimethylaniline may also influence the propagation step in the polymeris-ation of $-substituted styrenes by assisting the hyperconjugation effect.41The termination step in the polymerisation of styrene has been studiedwith a model polystyrene radical obtained by decomposing 1 : 1'-azobis-(1 : 3-diphenylpentane) .42 The results confirm termination by combinationrather than disproportionation over the range 25-144".The high ratesand molecular weights obtained with persulphate initiators in emulsionyolymerisations have also been observed under homogeneous conditions.The termination rate is decreased by the mutual repulsion of the ion-radicalactive centres.43 The polymerisation of vinyl acetate by high-energyradiation has been studied44 and a number of monomers have been poly-merised in the crystalline state by y-radiati~n.~~ Other studies include thepolymerisation of ethyl a~rylate,*~ methyl rnetha~rylate,~~ vinyl chloride,48and the dye-sensitised photopolymerisation of styrene.49The initiation constants of nine acyl peroxides have beendetermined for the polymerisation of methyl methacrylate.5o The decom-position of acetyl benzoyl peroxide,51 ethyl methyl ketone peroxide,52a-cumyl peroxide,% and organosilyl peroxides 54 has been studied. Theeffect of oxygen on the decomposition of azoisobutyronitrile and benzoylperoxide in aromatic solvents has been investigated. 55 Cyclic peroxideshave only weak initiating activity under normal conditi~ns,~B but in redoxsystems their activity is comparable with that of other peroxides, indicatingmonoradical initiati~n.~' The incorporation of catalyst fragments inpolymer molecules has been studied by analytical and radioactive-tracermethods. By using 14C-labelled benzoyl peroxide it has been establishedthat benzoate groups can be completely removed from polystyrene chainsby hydrolysis, and the proportion of phenyl to benzoate end-groups accur-ately determined.58 The presence of 1-3-1.6 benzoate units per chain hasbeen ascribed to initiation together with some termination by the benzoyl-o~y-radical,~~ but there is evidence that it may become incorporated in theInitiation.4 1 M.Imoto and K. Takemoto, J . Polymer Sci., 1956, 19, 205.43 C. G. Overberger and A. B. Finestone, J . Amer. Chem. Soc., 1956, 78, 1638.43 I. Jarkovsky, V. Stannett, and M.Szwarc, J . Polymer. Sci., 1955, 18, 515.44 S. Okamura, T. Yamashita, and T. Higashimura, Bull. Chem. SOC. Japan, 1956,4 5 A. J. Restaino, R. B. Mesrobian, H. Morawetz, D. S. Ballantine, G. J. Dienes, and4 6 Y. Hachihama and H. Sumimoto, Technol. Reports Osaka Univ., 1955, 5, 491.4 7 T. E. Ferington and A. V. Tobolsky, J . ColEoid Sci., 1955, 10, 536.4 8 F. Danusso and F. Sabbioni, Chinzica e Industria, 1955, 37, 1032; F. Danusso,49 H. Miyama, J . Chem. SOC. Japan, 1955, 76, 1361; 1956, 77, 601.51 J. Muller, Coll. Czech. Chem. Comm., 1956, 21, 216.53 M. R. Gopalan and M. Santhappa, Current Sci., 1956, 25, 116.53 H. C. Bailey and G. W. Godin, Trans. Faraday SOC., 1956, 52, 68.54 W. Hahn and L. Metzinger, Makromol. Chem., 1956, 21, 113.6 5 G.A. Russell, J . Amer. Chenz. SOC., 1956, 78, 1044.6 6 R. Zand and R. B. Mesrobian, ibid., 1955, 77, 6523.6 7 W. Hahn and A. Fisher, Makromol. Chem., 1956, 21, 106.5 * J. C. Bevington and C. S. Brooks, J . Polymer Sci., 1956, 22, 257.5s M. M. Koton, J. M. Kiselova, and M. J. Bessenov, Doklady Akad. Nazik S.S.S.R.,29, 647.D. J . Metz, J . Amer. Chem. SOC., 1956, 78, 2939.F. Sabbioni, and L. Siliprandi, ibid., 1956, 38, 99.N. G. Saha, U. S. Nandi, and S. R. Palit, J . , 1956, 427.1954, 96, 8552 GENERAL AND PHYSICAL CHEMISTRY.polymer by a mechanism independent of the polymerisation process.@The activity of tetra-alkylthiuram disulphides as thermal initiators hasbeen confirmed. Diphenyl and dibenzoyl disulphides are more effective asphotosensitised initiators for styrene than azoisobutyronitrile or benzoylperoxide, but do not a k t as thermal initiators up to 120O.61 The attack ofthionyl and bromine radicals on double bonds has been discussed in terms ofthe reversible formation of a radical complex as the initial step.62The redox initiations of the polymerisation of methacrylic acid andacrylonitrile by peroxidic compounds has been investigated.The induceddecomposition of peroxides by dimethylaniline has been studied in a numberof systems,a*66*66 but no clear mechanism has yet emerged. Benzoylperoxide with NN-dimethylaniline can initiate the polymerisation of methylmethacrylate in the range -40" to + Z O O , well below the temperatures atwhich the peroxide alone will initiate it.In this range the initial rate de-pends only on the product [Peroxide]i[DMA]i and a bimolecular reaction isp o ~ t u l a t e d . ~ ~ Imoto and Takemoto have found that the rate of decom-position of benzoyl peroxide by a number of di-N-alkylanilines is closelyconnected with the ionisation constant of the base,68 and favour a directattack on the peroxide bond, while Horner and Kirmse consider the first stepto be the formation of an undefined complex which breaks down by electrontransfer to give eventually a DMA radical, a benzoyloxy-radical, and benzoica ~ i d . ~ Q Bond has criticised both mechanisms and has suggested a com-promise. 70Solutions of ceric salts, normally used as photosensitised initiators, willalso polymerise acrylonitrile and methyl methacrylate in the dark.71 Ferric-oxalate complex has been used as a photosensitised initiator, the kineticsindicating initiation by the oxalate radical-ion, and termination by recom-b i n a t i ~ n . ~ ~ The polymerisation of ethylene at 250-300" sensitised by thethermal decomposition of ethyl iodide in the presence of mercury vapour hasbeen studied by using 14C-labelled ethyl iodide. An equilibrium betweenethyl iodide, mercury, mercuric iodide, and ethyl radicals is probablyinvolved. 73Kinetic experiments on the inhibition ofmethyl methacrylate polymerisation by moIecular oxygen show that exactly1 : 1 copolymerisation occurs during the inhibition period. The chain lengthis reduced by a factor of 65 and termination takes place by the Combinationof two oxygenated chain ends.The rate constant for oxygen addition toRetardation and inhibition.60 R. L. Dannley and E. L. Kay, J . Polymer Sci., 1956, 19, 87.til T. Otsu, ibid., 1956, 21, 559.63 C. Sivertz, W. Andrews, W. Elsdon, and K. Graham, ibid., 1956, 19, 587.63 T. M. Gritzenko and S. S. Medvedev, Zhur.fiz. Khim., 1956, 30, 1238, 1513.64 T. Azumi and Y . Okada, J . Chene. Soc. Jafian, Ind. Chem. Sect., 1956,59,30.6 5 H. Takatsugi, ibid., p. 260.6 6 M. Imoto, T. Otsu, and T. Ota, ;bid., p. 700.6 7 K. F. O'Driscoll and A. V. Tobolsky, J . Colloid Sci., 1956, 11, 244.6 8 M. Imoto and K. Takemoto, J . Polymer Sci., 1956, 19, 579.69 L. Horner and W. Kirmse, Annalen, 1966, 597, 48, 66.7O W. B. Bond, J . Polymer Sci., 1966, 22, 181.7 1 J.Saldick, ibid., 1966, 19, 73.'2 R. V. Subramian and M. Sahthappa, Current Sci., 1956, 25, 218.73 V. B. Sefton and D. J. LeRoy, Caiznd. .I. Chew., 1956, 34. 41KINETICS OF CHEMICAL CHANGE. 63the growing chain is at least five orders of magnitude higher than that formonomer additiom7* Similar copolymers have been obtained by the adionof oxygen on metha~rylonitrile,~~ indene,76 and styrene 77 polymerisations.Polymeric styrene peroxide is explosive above 50" c, breaking down to benz-aldehyde and formaldehyde. Peroxidic copolymers are also believed to betransient intermediates in the persulphate-initiated polymerisation ofacrylonitrile, methyl vinyl ketone, and methacrylonitrile in aqueous solu-t i ~ n . ? ~ The addition of sulphur to the bulk thermal polymerisation ofstyrene causes inhibition owing to the formation of polysulphides, whichreact subsequently with growing chains to form disulphides. These canbreak down to free radicals, giving further initiation, so that the rate ofpolymerisation is initially slower than the thermal rate, and eventuallybecomes faster.79 The inhibition of methyl acrylate polymerisations by anumber of substituted benzoquinones has been compared with that ofmethyl methacrylate.sO The redox reaction of metallic salts with growingradicals has been investigated.15* l7 The polymerisations of acrylonitrileand acrylamide are retarded, and that of styrene inhibited, by ferric salts,while growing poly(methy1 methacrylate) radicals react slowly, if at all, withferric ion.In view of the inefficiency of diphenylpicrylhydrazyl as a radical trap,81an attempt has been made to find a more trustworthy inhibitor.A stablefree radical obtained by the oxidaton of the condensation product of acetonewith phenylhydroxylamine gives a well-defined inhibition period in styrenepolymerisation, and the products do not affect the reaction, but the stoicheio-metry during the inhibition period is uncertain.82Transfer constants with eleven solvents have been measuredfor the polymerisation of methyl acrylate. These are found to be consis-tently higher than those obtained with methyl methacrylate, possibly owingto a steric effect. The efficiency of alkylbenzene solvents as chain-transferagents varies with the reactivity of the paraffinic hydrogen atoms in theorder tertiary > secondary > primary, benzene having the lowest transferconstant, and isopropylbenzene the highest.= Measurements of the transferof 2-vinylpyridine radicals with 9-chlorotoluene support the view that thealkyl side-chain rather than the benzene nucleus of the solvent is involved.84Transfer constants for the polymerisation of ethyl acrylate in varioussolvents have been determined,86 and transfer to thiols in the polymerisationof methyl methacrylate has been further investigated.8s A comparisonTransfer.74 G.V. Schulz and G. Henrici, Makrornol. Chem., 1956, 18/19, 437.16 S. F. Strause and E. Dyer, J . Amer. Chem. SOC., 1956, 78, 136.76 G. A. Russell, ibid., pp.1035, 1041.7 7 A. A. Miller and F. R. Mayo, ibid., pp. 1017, 1023.78 E. Dyer, 0. A. Pickett, jun., S. F. Strause, and H. E. Worrell, jun., ibid., p. 3384.79 P. D. Bartlett and D. S. Trifan, J . Polymer Sci., 1956, 20, 457.80 J. L. Kice, ibid., 1956, 19, 123.8 1 J. C. Bevington, J . , 1956, 1127.82 J. C. Bevington and N. A. Ghanem, ibid., p. 3506.83 A. D. Gadkary and S. L. Kapur, Makrornol. Chem., 1955.1'7, 29.84 R. L. Dannlep, J. A. Schufle, I. Cohen, and J. R. Chambers, J . Polymer Sci., 1956,8 6 Y. Hachihama and H. Sumimoto, Teehnol. Beports Osaka Univ., 1955, 5, 485.86 S. Fujii, S. Tanaka, and S. Sutani, J . Polymer Sci., 1956, 20, 584.19, 28554 GENERAL AND PHYSICAL CHEMISTRY.has been made of the transfer activity of a number of tertiary amines in thebulk polymerisation of acrylonitrile, and of triethylamine with five vinylmonomers.87 The chain transfer of styrene with an aliphatic nitrile, thiol,primary and secondary alcohol,88 and Q- and P-bromostyrene 89 has beenmeasured.In vinyl benzoate polymerisations chain transfer to the aromaticnucleus of the polymer and monomer has been confirmed.90Copolymerisation. The copolymerisation of methyl methacrylate andmaleic anhydride behaves abnormally 91 in that an increased rate of reactionis obtained with increasing proportion of maleic anhydride, possibly due tosensitivity of the cross-termination coefficients to a change of environment.In the formation of peroxidic copolymers with acrylonitrile, methyl vinylketone, and methacrylonitrile, the order of reactivity of the monomers withthe peroxy-radical agrees with that of the Alfrey-Price Q-values for thesemonomers.78 An equation has been derived correlating the degree of poly-merisation with the copolymerisation rate and various rate constants,which should permit the experimental determination of cross-terminationand cross-transfer constants.92 Measurements of the heat of copolymeris-ation of methyl methacrylate and acrylonitrile show that the steric strainpresent in 1 : 1-disubstituted polymers is partly relieved by the incorpor-ation of l-monosubstituted monomer units into the chaineg3 The size of thealkyl group in trialkyl aconitates,M and of the acyl chain in vinyl esters,Q5has no effect on their reactivity ratios with a number of vinyl monomers.Monomer reactivity ratios have also been determined in the systems vinylstearate-vinyl acet at e,96 poly (et hylene fumarat e)-met hyl met ha~rylate,~’diethyl vinylphosphonate-styrene,g8 and for the copolymerisation of vinyl-idene cyanide with a wide range of common monomers.9g The results arein good agreement with parameters calculated for vinylidene cyanide bythe Q-e method.A number of simple vinylsiloxanes have been copolymerised with organicvinyl monomers and are shown to have reactivities comparable with that ofvinyl acetate or vinyl chloride.lW Vinyltriethoxysilane and eleven othervinylsilanes give copolymers with vinyl chloride and acrylonitrile.101 Ally1monomers, which give only low-molecular weight homopolymers , have been137 C.H. Bamford and E. F. T. White, Trans. Faraday SOC., 1956, 52, 716.88 M. Morton, J. A. Cala, and I. Piirma, J . Amer. Chem. SOC., 1956, 78,89 M. H. Jones, Canad. J . Chem., 1956, 84, 108.90 G. Smets and A. Hertoghe, Makromol. Chem., 1956, 17, 189.9 1 D. C. Blackley and H. Melville, ibid., 1956, 18/19, 16.92 S. R. Palit, Trans. Faraday SOC., 1955, 51, 1720.93 J . H. Baxendale and G. W. Madras, J . Polymer Sci., 1956, 19, 171.94 C. S. Marvel, J. W. Johnson, jun., J . Economy, G. P. Scott, W. K. Taft, and B. G.95 L. P. Witnauer, N. Watkins, and W. S. Port, ibid., p. 213.96 A. Adicoff and A. Buselli, ibid., 1956, 21, 340.9 7 M. Gordon, B. M. Grieveson, and I . D. McMillan, ibid., 1956, 18, 497.@ * C. L. Arcus and R. J .S. Matthews, J.. 1956, 4607.DD H. Gilbert, F. F. Miller, S. J. Averill, E. J. Carlson, V. L. Folt, H. J . Heller,F. D. Stewart, R. F. Schmidt, and H. L. Trumbull, J. Amer. Chem. SOC., 1956, 78,1669.5394.Iabbe, ibid., 1956, 20, 437.100 R. M. Pike and D. L. Bailey, J. PoZymer Sci., 1966, 23, 66.lo1 B. R. Thompson, ibid., 1956, 19. 373KINETICS OF CHEMICAL CHANGE. 55successfully copolymerised with several monomers to give high-molecularweight compounds.lo2P lo3Branching : block and graft copolymers. The comparative activities inhydrogen abstraction of some initiating radicals have been determined semi-quantitatively.88 Oxy-radicals appear to be only five to ten times moreactive in hydrogen abstraction than carbon radicals, so that primary radicalsderived from peroxide initiators are unlikely to affect the degree of branchingof a polymer chain, in view of the relatively large concentration of growingradicals.The formation of graft and block copolymers has been reviewed l0Q andsome known methods have been improved and extended.lo5 Graft co-polymers of methyl methacrylate and styrene have been made by the ultra-sonic degradation of a solution of the polymers,lo6 by y-irradiation of poly-(methyl methacrylate) in the presence of styrene monomer,lo7 and by usingbrominated polystyrene as a photochemical initiator for methyl methacrylatenionomer.lo8 In the photodegradation of poly(methy1 vinyl ketone) poly-meric free radicals are produced which can form graft polymers in the pre-sence of vinyl monomers.lo9 Amino-groups in poly-(9-aminostyrene) havebeen converted into N-acetyl-N-nitrosoarylamino-groups, which can initiatethe polymerisation of acrylonitrile to give a graft polymer.l1° The methodof cold mastication of a polymer in the presence of a monomer has beenwidely applied.lll Barnard has described a neat method of characterisingthe synthetic chains in interpolymers of natural rubber with syntheticpolymers, involving degradative ozonolysis of the rubber trunk chains,leaving the polymer chains intact .l12Szwarc, Levy, and Milkovich have reported a method for the preparationof block copolymers which is likely to have wide applications. The initiationof the polymerisation of styrene by a sodium-naphthalene complex gives,eventually, a growing chain with an anionic active centre at both ends.The carbanions do not terminate, and a living I' polystyrene is obtainedwhich can initiate polymerisation in other monomers, forming block co-polymers.A number of monomers can be added in succession, and theprocess stopped at any stage, so that considerable controlled variation incomposition is p0ssib1e.l~~Ionic Polymerisation.-The polymerisation of styrene by stannic chloridein benzene and carbon tetrachloride has been investigated. The inductionperiod peculiar to these solvents does not appear to be due to HCI produced102 G. Oster and Y . Mizutsni, J . Polymer Sci, 1956, 22, 173.103 A. Drucker and H. Morawetz, J . Amer. Chem. SOC., 1956, 78, 346.104 E. H.Immergut and H. Mark, Makvomol. Chem., 1956, 18/19, 322.105 P. E. M. Allen, J. M. Downer, G. W. Hastings, H. W. Melville, P. Molyneux, and106 A. Henglein, Makvoniol. Chem., 1956, 18-19. 37.107 D. S. Ballantine, A. Glines, D. J- Metz, J. Rehr, R. B. Mesrobian, and A. J.108 M. H. Jones, Canad. J . Chem., 1956, 34, 948.1L@ J . E. Guillet and R. G. W. Norrish, PYOC. Roy. SOC., 1955, A , 235, 172.110 'w. Hahn and A. Fischer, Makromol. Chem., 1956, 21, 77.111 D. J. Angier and W. F. Watson, J . Polymer Sci., 1956, 20, 235.113 hl. Szwarc, M. Levy, and R. Milkovich, J . Anzer. Chenz. Soc., 1956, 78, 2656.J . K. Urwin, Nature, 1956, 177, 910.Restaino, J . Polyntev Sci., 1956, 19, 219.D. Barnard, ibid., 1956, 22, 21356 GENERAL AND PHYSICAL CHEMISTRY.by hydrolysis of the catalyst, as previously suggested.l14 The kinetic resultsare ill-defined, probably owing to variations in the unknown water content,but there is a distinct difference of order and rate of reaction in the twoLittle is knownabout the stoicheiometry of possible initiating complexes in Friedel-Craftspolymerisation, but some related stable complexes have been reported.With aluminium bromide 116 benzene forms a complex A1,Br6,2C,H, whilealuminium chloride 117 gives 1 : 1 complexes with methanol, ether, and tetra-hydrofuran in benzene solution, and reacts with water to give AlC1,OH.Some progress has been made by the use of simplified systems whichavoid the inherent experimental difficulties of Friedel-Crafts catalysts.Evans, Jones, and Thomas 11* have studied the dimerisation of 1 : l-di-phenylethylene catalysed by trichloroacetic acid, and have shown that thereaction involves three molecules of the catalyst, two of which are believedto contribute to the solvation of the reaction of the monomer ion with asecond monomer molecule, whereas in the dimerisation of di-e-methoxy-phenylethylene the rate-determining step is the formation of the monomerThe polymerisation of styrene by trifluoroacetic acid has beeninvestigated in solvents of varying dielectric constants, and in the undilutedacid.120 In the latter practically instantaneous polymerisation occurs,giving high-molecular weight polymer.The abnormally high rate isascribed to solvation of the anionic half of the active complex by acidmolecules, retarding the recombination which normally terminates thegrowing chain.The molecular termination constants of mono- and fi-di-alkylbenzenes in the cationic polymerisation of styrene indicate that transfertakes place to the aromatic nucleus rather than to the side-chain of the alkyl-benzenes. Any branches arising from transfer to the polymer are thereforelikely to be attached to phenyl nuclei.121The use of a sodium-naphthalene complex to initiate an essentiallyanionic polymerisation of vinyl monomers has been described 113 (see p. 55).With styrene, the naphthalene anion acts as an electron-transfer agent,giving an ion-radical which grows at both ends, one free-radical and theother anionic. As soon as the two ends are appreciably separated theradicals terminate by mutual combination, giving chains with propagatinganions at both ends, which do not terminate.This method of initiation isnot restricted to conjugated monomers, and has been used with methylmethacrylate.f22 In this case, however, the polymer does not remain “ alive,’’owing to a rapid self-terminating reaction. Complexes formed betweensodium and polynuclear aromatic hydrocarbons have been studied. 123although their dielectric constants are similar.114 S. Okamura and T. Higashimura, J . Polymer Sci., 1956, 20, 581.1 1 5 Idem, ibid., 1956, 21, 389.118 F. Fairbrother and K. Field, J., 1956, 2614.117 J . R. Bercaw and A. B. Garrett, J . Amer. Chem. SOC., 1956, 78, 1841.118 A. G. Evans, N.Jones, and J. H. Thomas, J., 1955, 1824.119 A. G. Evans, N. Jones, P. M. S . Jones, and J. H. Thomas, J . , 1956, 2757.120 J. J. Throssell, S. P. Sood, M. Szwarc, and V. Stannett, J . Amer. Chem. SOC.,121 C. G. Overberger, G. F. Endres, and A. Monaci, ibid., p. 1969.112 M. Szwarc and A. Rembaum, J . Polymer Scz., 1956, 22, 189.12s D. E. Paul, D. Lipkin, and S. I. Weissman, J . Anter. Chem. SOC., 1956, 78, 116.1956, 78, 1122KINETICS OF CHEMICAL CHANGE. 67Stereospecific PoLymerisaticm.-A thorough review of the availableinformation on the Ziegler process as applied to ethylene has been given inVol. XI of the Interscience “ High Polymers ” series.124 Further work onthe structure of crystalline poly-a-olefins has appeared 125 and has beensummarised by Natta.1z6 The long-standing problem of synthesising“natural” rubber has been virtually solved by the polymerisation ofisoprene with stereospecific catalysts to give a cis-1 : Ppolyisoprene, whichhas practically the same structure and molecular-weight distribution asHevea r~bber.12~, 128 Details of stereospecific catalysts are scarce, but it isbecoming apparent that there may be a considerably greater range of suchcatalysts than was at first supposed.In addition to variants of the Zieglerpr0cess,1~Q finely-divided lithium metal 127 has been used to make stereo-specific polyisoprene. Other alkali metals give only amorphous polymerunder the same conditions. Chromium oxide supported on a silica-aluminabase gives fairly crystalline polyethylene at moderate pressures,lm but withrt-but-l-ene gives only 1-3% of isotactic polymer, compared with 60-70%obtained with Al(C,H,),-TiCl, complex as ~ a t a 1 y s t .l ~ ~ Schildknecht andDunn 132 have obtained crystalline poly(ksobuty1 vinyl ether) using borontrifluoride-ether complex as catalyst in propane at -70” to -80”. Thepolymer is precipitated as a swollen solid phase, but propagation is believedto take place homogeneously, in contrast with other systems. It is thoughtthat a slow or diffusion-controlled propagation step may allow time for theorientation of polarised monomer molecules approaching the carbonium ion.A new development in both catalyst and monomer is the stereospecificpolymerisation of optically active propene oxide by powdered potassiumhydroxide, and by a ferric chloride-propene oxide complex.133 The stereo-specific reaction is heterogeneous, and does not destroy the asymmetriccentre of the monomer, so that optically active crystalline polymer isobtained. There is also a concurrent homogeneous reaction which is notstereospecific, and gives amorphous inactive polymer, the net productbeing a mixture of amorphous (70%) and crystalline (30%) forms. Withracemic monomer a similar mixture is found, the crystalline portion beingan inactive mixture of chains which have individually either all (+) orall (-) units.la With potassium hydroxide as catalyst, (-)-propene oxide124 R. A. V. Raff and J. B. Allison, “ Polyethylene,” Interscience, New York, 1956.1~ G. Natta and P.Corradini, J. Polymer Sci., 1956, 20, 251 ; Idem, Angew. Chem.,1956, 68, 615; G. Natta, L. Porri, P. Corradini, and D. Morero, Atti Accad. naz. Lincei,Rend. Clusse Sci. fis. mat. nut., 1956, 20, 560; G. Natta, P. Corradini, and L. Porri,ibid., p. 728.lZ6 G. Natta, Chimica e Industria, 1966, 88, 761 ; Angew. Chem., 1956,68, 393.127 F. W. Staveley and co-workers, Ind. Eng. Chem., 1956, 48, 778.1 2 ~ S. E. Home, jun., J . P. Kiehl, J . J. Shipman, V. L. Folt, C. F. Gibbs, E. A.12B C. D. Nenitzescu, C. Huch, and A. Huch, Angew. Chem., 1956, 68, 438; K.130 A. Clark, J. P. Hogan, R. L. Banks, and W. C. Lanning, Ind. Eng. Chem., 1956,131 G. Natta, P. Pino, E. Mantica, F. Danusso, G. Mazzanti, and M. Peraldo, Chimica132 C . E. Schildknecht and P.H. Dunn, J . Polymer Sci., 1966, 20, 697.C. C. Price, M. Osgan, R. E. Hughes, and C. Shambelan, J . Amer. Chem. Soc.,nP C . C. Price and M. Osgan, ibid., p. 4787.Willson, E. B. Newton, and M. A. Reinhart, ibid., p. 784.Ziegler, Bull. SOC. chim. France, 1956, 1.48, 1152.e Industria, 1956, 38, 124.1956, 78, 69058 GENERAL AND PHYSICAL CHEMISTRY.gives a solid, highly crystalline (81%), optically active polymer, but withracemic monomer only liquid polymer is formed.It is generally agreed that in stereospecific polymerisation the propagat-ing active centre is attached to the initiating complex by a polarised bond,the addition of monomer involving the breaking and re-forming of this bondwith severe steric limitations, but whether this necessarily involves a two-phase interface is still an open question.RRirtg Polymerisation.-The heat, entropy, and free-energy changes in thehypothetical polymerisation of liquid cyclo-paraffins and derivatives havebeen estimated.135 Except for cyclohexane, the calculated free energy ofpolymerisation is negative at least up to cyclooctane. The polymerisationof heterocyclic compounds has been discussed in the light of these results.136Although cyclopropane is not affected by free-radical catalysts, it can bepolymerised to a low-molecular weight polymer by mercury photosensitis-ation.Ivin 13' has carried out a thorough analysis of the products of thisreaction, and concludes that diallyl radicals are formed as intermediates,giving a polymer which resembles polypropene rather than polyethylene.The polymerisation of oxacyclobutanes by boron trifluoride gives sub-stantially unbranched chains, but is not stereospecific, and gives normalkinetics for a water-cocatalysed oxonium-ion reaction.138 The existenceof polymeric sulphur radicals in equilibrium with S, rings has been con-firmed 139 by paramagnetic-resonance measurements between 189" and 414".The results are in quantitative agreement with Gee's treatment of this system.The polymerisation of DL-phenylalanine-N-carboxylic anhydride by low-molecular weight polysarcosine gives rates which are several hundred timesfaster than expected from known rate constants for simple primary- orsecondary-base catalysis.Rallard and Bamford 140 consider this to be dueto adsorption of the anhydride on the polysarcosine chain, increasing thecollision frequency with the active centre, and they suggest a possibleanalogy with enzyme action.The base-catalysed polymerisation of opticallyactive ethyl y-benzyl-N-carboxy-L-glutamate is autocatalytic, and proceedsalmost twenty times as fast as the polymerisation of the racemic form.141It has been shown that the optical isomers form helical polymer chains withopposite screw directions, to which they add preferentially, and whichexercise a steric effect on the rate of addition.142Further studies have been made of the equilibrium between linear polymerand water in the polymerisation of 6-hexanolactam. Vapour-pressuremeasurements show that most of the water is present in the liquid ratherthan the vapour phase,143 and Fukumoto has shown that the change of135 F.S. Dainton, T. R. E. Devlin, and P. A. Small, Trans. Favaday SOC., 1955, 51,186 P. A. Small, ibid., p. 1717.197 K. J. Ivin, J., 1956, 2241.la* J. B. Rose, ibid., p. 542.130 D. M. Gardner and G. K. Fraenkel, J . Amei'. Chenz. Soc., 1956, 78, 3279.140 D. G. H. Ballard and C . H. Bamford, Nature, 1956, 177, 477; Pvoc. Rqy. Sor.,1710.1956, A , 236, 384.141 E. R. Blout and M. Idelson, J . Amer, Cham. SOC., 1956, 78, 3857.P. Doty and R. D. Lundberg, ibid., p. 4810.143 F. Wiloth and W. Dietrich, Makromol. Chettr., 1966, 21, 50KINETICS OF CHEMIC-4L CHANGE. 59activity of water with temperature has a much greater effect on the degreeof polymerisation than the change of equilibrium constant with temper-ature.lU Meggy has evaluated the activity coefficients of water andpolymers 145 and has constructed a composition-temperature diagram in therange 200-300".The relative proportions of individual cyclic oligomerspresent have been determined 146 at 221" and 253", and the alkali-catalysedpolymerisation has been studied.147Degradation and Depolymerisatiort.-During the thermal degradation ofpoly(methy1 methacrylate) 148 and of polystyrene,149 slow random splittingoccurs in addition to a fast depolymerisation. The predominant gaseousproducts of the thermal degradation of polyacrylonitrile are hydrogencyanide and ammonia,lS and the heat-stable residue probably consists offused pyridine rings formed by the intramolecular linking of adjacent nitrilegroups. 151 The thermal degradation of poly(propy1ene glycol) is governedby the instability of the radical formed on carbon atoms adjacent to an etherlink. 152and the effect of cross-links on the thermal degradation of rubber i n vacziohas been examined.'"On the basis of quantum-yield measurements for the photochemicaldecomposition of hydrogen peroxide in the presence of poly(methacry1icacid), Baxendale and Thomas 155 conclude that the observed degradation ofthe polymer is due to carbon-carbon splitting by the hydroxyl radical.Alexander and Fox 156 do not consider this explanation likely, and havesuggested that peroxide impurities in the polymer are responsible.Thecharacteristic coloration of polymethacrylonitrile when heated above 120" isshown to be due to a reaction initiated at impurities in the polymer chain,and can be eliminated by polymerisation in vacuo with rigorous purificationof the monomer.1s7 Other studies include the effect of pressure on theultrasonic degradation of polystyrene in benzene solution 158 and the solid-state degradation of poly(methy1 methacrylate) and cellulose acetate byy - r a y ~ .~ ~ ~Simha has discussed the degradation of branched-chain moleculesE. W.J. H. B.R. 0. C.144 0. Fukumoto, J . Polymer Sci., 1956, 22, 263.146 A. B. Meggy, J . , 1956, 4876.146 D. Heikens, Rec. Trav. chim., 1956, 75, 1199.147 Idem, Makromol. Chem., 1956, 18-19, 62.148 A. Brockhaus and E. Jenckel. ibid., p.262.149 I;. W. Morthland and W. G.. Brown, J . Amer. Chem. SOC., 1956, 78, 469.160 H. Nagao, M. Uchida, and T. Yamaguchi, J . Chem. SOC. Japan, Ind. Chem. Sect.,lbl W. J. Burlant and J. L. Parsons, J . Polymer Sci., 1956, 22, 249.162 J. R. Thomas, J . Amer. Chem. SOC., 1955, 77, 6107.163 R. Simha, J . Chew. Phys., 1956, 24, 796.15' S. Straus and S. L. Madorsky, Ind. Eng. Chem., 1956, 48, 1212.166 J . H. Baxendale and J. K. Thomas, Chem. and Ind., 1956, 377.166 P. Alexander and M. Fox, ibid., p. 1385.157 N. Grassie and I. C. McNeill, J., 1956, 3929.168 H. W. W. Brett and H. H. G. Jellinek, J . Polywzev Sci., 1956, 21, 536; H. H. G.lb0 A. Chapiro, J . Chim. phys., 1956, 53, 295.1956, 59, 698, 940.Jellinek, ibid.. 1956, 22, 14960 GENERAL AND PHYSICAL CHEMISTRY.3.ADSORPTION AND HETEROGENEOUS CATALYSIS.This Report has been separated from the section on the Kinetics ofChemical Change this year because it seemed appropriate to include infonn-ation on physical adsorption as well as chemisorption and catalysis. Mostof the work on adsorption reported relates to the gas-solid interface sinceadsorption at other interfaces can be treated more conveniently underColloid Chemistry or Surface Chemistry.Adsorption.--Several important reviews have appeared. One of theseby de Boer is comprehensive; there are others on more specialised topicssuch as chemisorption and catalysis on oxide semiconductors,2 surface-barrier effects in ad~orption,~ the latest techniques in field-emission micro-scopy,4 recent work on metal surfaces including the results obtained byfield-emission studies and the electronic interaction between metalliccatalysts and chemisorbed molecules.g Reyerson has also given a generalreview of various aspects of adsorption.Physical adsorption.Although the methods of measurement of surfacearea have become fairly well standardized, work continues in this field.Rosenberg has shown that an accuracy of 1% can be obtained for surfacesas small as 50 cm.2 by using a thermistor unit to measure adsorption ofkrypton at low pressures. Haulg has confirmed that krypton is moresuitable than nitrogen for measuring low surface areas. The " point-B "method* has been examined for a series of oxides; although differentpressures were observed at low coverages, the same pressure was required togive lOOyo coverage of different samples of the same oxide.It was suggestedthat the pressure corresponding to point-B was determined by the filling ofthe least active regular sites and so was not influenced by differences inthe heterogeneity of samples. MacIver and Emmett l1 showed that the B.E.T.isotherm is obeyed by nitrogen adsorbed on sodium chloride at relativepressures of 0.014.1 in contrast to the usual range of 0-05--0*35 and theysuggested that this was due to the comparative homogeneity of the surface.Several papers have appeared on various aspects of the thermodynamicsof adsorption and in particular on the information which can be derived byentropy measurements. The values of zero-point entropies of kryptonadsorbed on anatase l2 have been shown to be in accord with values expectedfor a heterogeneous surface and the retention of the amount of randomnesscorresponding to 50" K.Similar results have been reported for krypton1 J. H. de Boer, Adv. Catalysis, 1956, 8, 18. * G. Parravano and M. Boudart, ibid., 1955, 7, 50.5 S. R. Momson, ibid., p. 269.4 R. Gomer, ibid., p. 93.6 J. A. Becker, ibid., p. 135.R. Suhrmann, ibid., p. 303.7 L. H. Reyerson, Ann. Rev. Phys. Chem., 1956, 7, 383.8 A. J. Rosenberg, J . Amer. Chem. Soc., 1956, 78, 2929.9 R. A. W. Haul, Angew. Chem., 1956, 68, 238.10 P. Royen, A. Orth, and K. Ruths, 2. anorg. Chem., 1955, 281, 1.11 D. S. MacIver and P. H. Emmett, J . Phys. Chem., 1956, 80, 824.14 E.L. Pace, W. T. Berg, and A. R. Siebert, J . Amer. Chem. Soc., 1956, 78, 1631.* I.e., the method based on the assumption that one layer of adsorbed molecules hasformed at the point where the isotherm bends over sharply and becomes linearKEMBALL ADSORPTION AND HETEROGENEOUS CATALYSIS. 61adsorbed on r~ti1e.l~ Barrer and Stuart l4 have shown that characteristicsigmoid isotherms, such as are found for the sorption of water and methanolby carbon, can be interpreted by a statistical-thermodynamical treatmentbased on localized adsorption on a uniform surface with exothermic lateralinteraction. Various models for intracrystalline sorption, i.e. , localized andmobile with either one or two degrees of translational freedom, have beenexamined.15 ,4pplication l6 of these models to the sorption of argon inchabazites l 7 has shown that from coverages of 0.1 to 0.7 mobile adsorptionwith only one degree of translational freedom and two degrees of vibrationalfreedom appears to operate but that at higher coverages the mutual cagingof the molecules leads to localized adsorption.Very similar conclusionswere obtained from measurements of the thermodynamic properties ofoxygen sorbed in chabazites 18 but some restriction of rotational freedomwas noted even at the lower coverages. Kington l9 has given an explanationof the maximum in the experimental heat of sorption of argon in chabaziteas the coverage is increased, in terms of the packing of the atoms into cagesin the adsorbent. Each cage can hold two atoms at the normal equilibriumspacing but an additional atom can be packed in although this requires somecompression with consequent decrease in heat of sorption at high coverages.Siebert and Pace 2O have measured heat capacities of multimolecular layersof nitrogen trifluoride adsorbed on anatase.Evidence for a transitioncorresponding to fusion of the solid was found to occur between 60" and66" K but only when the coverage was as high as 5.9 monolayers. A newdefinition of a two-dimensional standard state applicable to systems wherethe surface pressure is either measured or calculated has been putVarious papers have been published on physical absorption involving avariety of adsorbates and adsorbents. The adsorption of diborane onboron nitride and on palladium-on-charcoa122 has been shown to fit theLangmuir equation at low pressures and to be limited to van der Waal'sadsorption with no evidence of chemisorption.This work has also beenextended to cover the adsorption of diborane, deuterodiborane, and tri-methylborane on palladium and on charcoal.23 In these cases too, nochemisorption was observed although the heat of adsorption of diborane oncharcoal amounts to 5 to 10 kcal./mole. The heat of adsorption of n-butylalcohol from aqueous solutions on a Graphoii (a commercial graphitisedcarbon black) surface has been obtained by measurement of heats of im-rner~ion.~~ Accommodation coefficients of various gases on glass have beenreported by Schafer and Ger~tacker.~~l3 E.L. Pace, K. S. Dennis, and W. T. Berg, J. Chena. Phys., 1955, 23, 2166.R. M. Barrer and W. I. Stuart, J., 1956, 3307.l6 L. A. Garden and G. L. Kington, Proc. Roy. SOC., 1966, A , 234, 24.l6 L. A. Garden, G. L. Kington, and W. Laing, ibid., p. 35.Idem, Trans. Faraday SOC., 1955, 51, 1558.L. A. Garden and G. L. Kington, ibid., 1966,52, 1397.la G. L. Kington, ibid., p. 475.*O A. R. Siebert and E. L. Pace, J. Phys. Chem., 1956, 80, 828.21 H. L. Harter, P. R. Rider, and P. M. Williamson, J. Chem. Phys., 1955,23, 1966. ** H. C. Beachell and H. S. Veloric, J. Phys. Chem., 1946, 60, 102.2s H. C. Beachelland K. R. Lange, ibid., p. 307. '' G. J. Young, J. J. Cheswick, and F. H. Healey, ibid., p. 394.K. Schafer and H. Gerstacker, 2. Elektuochent., 1956, S9, 102362 GENEK.41.-4ND PHYSICAI, CHEMISTRY.Chemisorption. In addition to the re~iews,l-~ Eley 26 has reportedbriefly on a symposium held on chemisorption at Keele (University Collegeof North Staffordshire) where various recent results and theories werediscussed. Investigations involving new and improved physical techniqueshave continued to yield important results, particularly on the nature ofchemisorbed species and on the electronic interaction between the adsorbateand the substrate.Very interesting developments of the magnetic investigations by Selwoodand his school have appeared. The forms of thermomagnetic curves ofsupported nickel catalysts 27 have been used to determine particle sizedistributions for diameters below 50 and the results obtained were inaccord with measurements from X-ray line-width broadening. However, amore important development from the point of view of chemisorption wasthe demonstration that adsorption of gases on highly dispersed nickelparticles caused changes in magnetization.Hydrogen and ethylene causeda decrease in magnetization because they were acting as electron donors andfilling up holes in the d-band of the metal. The reverse effect was observedon the adsorption of nitrogen and oxygen. Selwood28 improved thetechnique so that changes of magnetization could be measured simultane-ously with adsorption and showed that the adsorption of hydrogen causedthe addition of 0.068 electron per nickel atom. Moore and Seiwood29extended the investigation to the adsorption of other gases-water, likehydrogen, caused a decrease in magnetization and nitrous oxide and carbonmonoxide behaved like oxygen and increased it.There was an excellentcorrelation with the results obtained on resistance changes caused by cherni-sorption reported by Suhrmann and Schulz30 in that those gases whichcaused a decrease in magnetization by contributing electrons to the metalsubstrate showed a decrease in the resistance of the substrate and vice versa.Selwood31 has reported a further improvement in the apparatus and moredetailed results with hydrogen on nickel including the effect of changes intemperature. He has been able to demonstrate the conversion of physicallyadsorbed into chemisorbed hydrogen and has also produced evidence ofchemisorbed hydrogen with a very low heat of adsorption.The techniqueis clearly important, and when extended to other adsorbates will providevaluable information about the nature of the link between adsorbate andmetal adsorbents. French and Howard 32 have shown by magnetic measure-ments that the adsorption of transition-metal ions takes place from solutionson silica gel without change in the electronic configuration of the ions. Theionic character of the adsorption was confirmed by the small amount ofadsorption occurring from weakly ionizing solvents.Resistance changes of nickel films have been followed by Rienacker and24 D. D. Eley, Nature, 1956, 178, 540.2 7 P. W. Selwood, S. Adler, and T. R. Phillips, J. Amer. Chem. SOC., 1955, 77,88 P. W.Selwood, ibid., 1956, 78, 249.89 L. E. Moore and P. W. Selwood, ibid., p. 697.90 R. Suhrmann and K. Schulz, J . CoZZoid Sci., 1964, Suppl. 1, 50.31 C. hI. French and J. P. Howard, Trans. Farads?! SOC., 1056, 52, 712.1462.P. W. Selwood, J . ,4??zer. Chew SOC., 1966, 78, 3893KEMBALL .4I)SORPTIOS AND H E'TEKOGEN EOUS CA'ltZ L Y S IS. 63H a ~ i s e n . ~ ~ ~ 34 As mentioned earlier, hydrogen causes a decrease in resistancebut the addition of oxygen to the hydrogen-covered film restores the resist-ance to a value slightly in excess of the initial value for a clean nickel surfaceowing to the oxidation of the surface, i.e., removal of electrons. Smallquantities of oxygen cause only a transitory increase in resistance and thena decrease as the oxygen is converted into water.Addition of butadiene orbenzene to the Ni-H film also causes an increase in resistance as the hydrogel1is used up. Various other reactions such as the decomposition of formic acidwere also studied but, in general, the main effects appear to be due tochanges in the amount of adsorbed hydrogen. Suhrmann and Schulz35have shown that very thin transparent films of non-oriented nickelbehave anomalously and exhibit a rise in resistance when hydrogen isadmitted.Eischens and his collaborators have continued their investigations on theinfrared spectra of adsorbed molecules. Detailed results have been obtainedfor carbon monoxide on palladium, nickel, and platinum36 over a widerange of pressure and temperature More evidence for a bridged structurefor adsorbed carbon monoxide 37 attached to two metal atoms was obtained.Changes in the spectra with coverage were attributed to interaction betweenthe adsorbed molecules.Most interesting results were obtained whenolefins and acetylenes were chemisorbed on nickel ; 38 the spectra indicatedthe presence of a structure -CH2-CH, on admission of ethylene and therewas no indication of the presence of a double bond with either ethylene orpropene. Admission of hydrogen to chemisorbed ethylene gave spectracorresponding to ethyl radicals and on prolonged pumping evidence wasobtained for C2H2 structures, mainly saturated but also partly with olefiniccharacter. Infrared absorption spectra have also been reported for ordinaryand heavy water on glass.39More results have been reported on the state of nitrogen adsorbed ontungsten determined by simultaneous recording of the rise in pressure andthe temperature of the tungsten wire as it is flashed.40$ 41 According to thelast of these papers there are four states of nitrogen on tungsten : 6 , stablebetween 100" and 140" K ; y, 140-250" K ; a, 300-650" K ; and p, 1400-1900" K. The adsorption of gases on a silicon surface has also been in-vestigated at pressures from to lo4 mm.of Hg by a desorption tech-n i q ~ e . ~ ~ In this case a filament of the adsorbent was flashed in a glassvessel attached to the inlet of a mass spectrometer and the gas desorbedmeasured in the spectrometer. Hydrogen and carbon monoxide werestrongly adsorbed on the silicon but no adsorption of nitrogen, argon, orcarbon dioxide was found, although the last gas decomposed to carbon33 G.Rienacker and N. Hansen, 2. aizorg. Chem., 1956, 284, 162.34 Idem, Angew. Chem., 1956, 08, 41.3 5 R. Suhrmann and K. Schulz, Naturwiss., 1955, 42, 340.36 K. P. Eischens, S . A. Francis, and W. A. Pliskin, J . Phys. Chem., 1956, 80, 104.3 7 Idem, J . Chem. Phys., 1954, 22, 1786.38 W. A. Pliskin and R. P. Eischens, ibid., 1956, 24, 482.39 V. A. Nikitin, A. N. Sidorov, and A. V. Karyakin, Z h w . fir*. K l i Z t ~ , 1956, 30, 117.4u G. Ehrlich, J . Clteni. Plzys., 1956, 24, 482.J1 G. Ehrlich and T. W. Hickmott, Nature, 1956, 177, 1045.42 J . T. Law and E. E. Francis, J . Phm. Chew., 1956, 60, 35364 GENERAL AND PHYSICAL CHEMISTRY.monoxide when the filament was heated to 800" c or above.Similarly, waterdecomposed to hydrogen to a marked extent at high temperatures and alsoto a small extent even at room temperature. Several layers of oxygenwere taken up by the surface and it was shown that there was a sharp fallin the probability of a molecule's being adsorbed on hitting the surface afterthe completion of one layer. In addition to observations obtained by these" rapid desorption " techniques others have followed '' rapid adsorptions "by means of a pressure gauge attached through a capillary tube to an adsorp-tion vessel. Provided sufficiently low pressures are used the rate of adsorp-tion can be obtained by the differences in the change of pressure with timewith and without an adsorbent present.has shown that the '' stick-ing probability " for carbon monoxide on evaporated nickel films is initially0.6 but falls steeply when the coverage of the surface exceeds 0.2, droppingto about This large decrease was explained interms of increasing activation energy for chemisorption as the surface iscovered. Using a similar technique, WagenerM has shown that there israpid adsorption of carbon monoxide and carbon dioxide on barium, stron-tium, and nickel but that the adsorption of the same gases on magnesium,aluminium, and silver is very slow or negligible. Bloomer 46 has investigatedthe effect of the operation of an ionization gauge on the up-take of gases bybarium getters.Detailed results about the diffusion of hydrogen and oxygen on the (011)face of tungsten have been obtained by fiekl-emission studies.46 Nuclearmagnetic resonance has been used to study the relaxation times for" libration " of water and methane adsorbed on anatase.4' Proton relax-ation times for a number of liquids adsorbed on y-alumina and relatedcatalysts have been reported by Hickmott and Selwo~d.~~Theoretical work has been continued on the effect of heterogeneity ofadsorbent surfaces on the adsorption isotherms. Hepler 49 has investigatedthe proper limits which should be used for the integration of the isothermequation when there is a distribution of sites of different energy and hasobtained equations relating the distribution and heat of adsorption.Danon 50 has shown that the distribution function can be obtained in anapproximate form if the isotherm is known for low pressures or concen-trations. An improved method of testing the Elovich equation, which hasbeen shown to be applicable to many systems involving chemisorption onheterogeneous surfaces, has been suggested.s1 Experimental evidence forthe heterogeneity of a platinum catalyst has been found by Bond whoexamined the proportion of chemisorbed deuterium which was readilyexchangeable with hydrogen and showed this proportion decreased withOdafor a coverage of 0.8.43 2. Oda, J . Chem. Phys., 1956, 25, 592.44 S. Wagener, J . Phys. Chem., 1956, 60, 567.4 5 R. N. Bloomer, Nature, 1956, 178, 1000.46 R. Wortman, R. Gomer. and R.Lundy, J. Chem. Phys., 1956, 24, 161.4 7 N. Fuschillo and J. G. Aston, ibid., p. 1277.4 8 T. W. Hickmott and P. W. Seiwood, J . Plays. CAem., 1956, 80, 462.49 L. G. Hepler, J . Chem. Phys., 1955, 23, 2110.60 J. Danon, J . Claim. phys., 1955, 52, 392.61 J. N. Sarmousakis and M. J. D. Law, J . Chern. Phys., 1956, 25, 178.52 G. C. Bond, J . Phys. Chem., 1956, 80, 702KEMBALL ADSORPTION AND HETEROGENEOUS CATALYSIS. 66decreasing temperature. Kubokawa and Toyama 53 have confirmed thetwo types of chemisorption of hydrogen found by earlier work on zinc oxideand have shown that the conductivity is increased only by the high-temperature chemisorption. Gray and Darby % have given a detailedaccount of the relationship between the kinetics of the adsorption of oxygenon an oxide and the variation in the semiconducting properties of the sub-strate.The central feature of the discussion is the assumption of a surfacezone, the relative thickness of which is temperature-dependent and structure-sensitive and which differs significantly from the bulk of the adsorbent.Experimental results on the oxygen-nickel oxide system are reported andanalysed in a second paper.55 Earlier theories of the oxidation of metalshave been modified by Grimley and Trapnell 56 by taking into account theexistence of a strongly held layer of chemisorbed oxygen.The adsorption of oxygen on porous silver has been investigated in detailby Temkin and K~l’kova.~’ In addition to rapid unimolecular adsorptionand slow adsorption they found evidence of a so-called “ deep chemi-sorption ” which they suggested was of general importance in heterogeneouscatalysis.Horiuti and Kita 58 have shown that the kinetics of the adsorptionof nitrogen on a doubly-promoted iron catalyst appear to indicate absorptionof nitrogen into the catalyst in addition to dissociative adsorption. Evidencefor lattice penetration by nitrogen has also been obtained on evaporatedmetallic films.59 Extensive results for the adsorption of ammonia on simplemetal halides have been reported by Huttig and Harth.m,61 The resultson sodium chloride showed that physically adsorbed ammonia was convertedinto chemisorbed ammonia with an activation energy of about 5 kcal./mole.A useful technique for the investigation of the heat of adsorption of oxygenon nickel, platinum, and silver at low surface coverages has been used byGonzalez and Parravano.62 They made use of the decomposition equilibriumof water vapour in order to obtain oxygen at low activity.The heat ofadsorption on nickel was close to that for the formation of the bulk oxidebut much higher values for the surface heats were found for platinum andsilver. No adsorption was detected on gold. Information about theadsorption of hydrogen on platinum-gold alloys has been derived from thecathodic polarization of the alloys in sulphuric acid.63 The ionization ofalkali metals 64 and potassium halides 65 on hitting platinum and tungstensurfaces at high temperatures has been studied by Datz and Taylor.Theadsorption of water on iron oxide has been investigated by heat-of-immersion53 Y. Kubokawa and 0. Toyama, J . Phys. Chem., 1956, 60, 833.64 T. J. Gray and P. W. Darby, ibid., p. 201.6 5 Idem, ibid., p. 209.66 T. B. Grimley and B. M. W. Trapnell, Proc. Roy. SOC., 1956, A , 234, 405.6 7 M. I. Ternkin-and N. V. Kul’kova, Doklady Akad. Nauk S.S.S.R., 1955,105, 1021.6* J. Horiuti and H. Kita, J . Res. Inst. Catalysis, Hokkaido Univ., 1956, 4, 132.E. Greenhalgh, N. Slack, and B. M. W. Trapnell, Trans. Faruduy SOC., 1956, 52,6o G. F. Hiittig and E. Harth, 2. Elektrochem., 1955, 59, 370.61 Idem, 2. anorg. Chern., 1955, 282, 110.62 0. D. Gonzalez and G. Parravano, J . Amer. Chem. Soc., 1956, 78, 4533.63 K. A. Lapteva, T. I. Borisova, and M. G.Slin’ko, Zhur. fiz. Khim., 1956, 30, 61.64 S. Datz and E. H. Taylor, J . Chem. Ph-ys., 1956, 25, 389.06 Idem, ibid., p. 395.865.REP. -VOL . LTIT 66 GEN E 11.4 I> AN 1) I'H YSIC .\I, CIT 17 M I ST HI'.measurements-approximately t wo-t hirds of the water was physicallyadsorbed, the remainder being chemisorbed.66 Entropy measurementsshowed that the physically adsorbed water at 25" c was localized.Catalysis.-A number of review articles have appeared. Baker andJenkins 67 have considered the electronic factor in heterogeneous catalysisand Hauffe 68 has summarized developments of importance in the theory ofsemiconductors. Cremer 69 has given a general account of the correlationsfrequently found between frequency factors and activation energies some-times described as the " compensation effect " or the '' theta rule." *Various specialized topics have also been reviewed : synthesis of ketones,70polymerization of ole fin^,^^ hydrogenation of coal,72 and the catalytic crack-ing of c ~ r n e n e .~ ~ Volume 4 of " Catalysis " 74 has been published and treatsin detail the Fischer-Tropsch and other allied syntheses but it also includesarticles on methanation (i.e., hydrogenation of oxides of carbon to methane) ,'i5liquid-phase hydrogenation of coal,76 and dehydroaromatization of hydro-carb0ns.~7A number of papers have appeared involving studies of properties ofcatalysts. Sabatka and Selwood 78 examined several nickel catalysts bythermomagnetic analysis and showed that disperse nickel has the samemagnetic moment at 0" K as massive nickel.However, amorphous nickelhas been shown to be inactive as a catalyst in the hydrogenation of benzene.7gThe resistance changes observed in evaporated nickel films on chemisorptionand subsequently during catalytic reactions have already been mentioned 33and the mechanism of the decomposition of formic acid has been examinedas we11.80 In an extension of earlier work 81 it has been shown that there is agood correlation between the electrical conductivity of silica-aluminacatalysts and the small amounts of sodium present in the catalyst.82 Theincreased conductivity associated with increased alumina is now attributedto the extra sodium introduced. No increase was observed on introducingpotassium.By examining the water-content of similar catalysts, Haldemanand Emmett 83 have shown that most of the active sites on the catalyst after6 6 F. H. Healey, J. J. Chessick, and A. V. Fraioli, ibid., p. 1001.6 7 M. McD. Baker and G. I. Jenkins, Ad7r. Catalysis, 1955, 7, 2 .Gs E. Cremer, ibid., p. 75.7O V. I. Komarewsky and J . R. Coley, ibid., 1956, 8, 207.71 E. K. Jones, ibid., p. 219.73 E. E. Danath, ibid., p. 239.73 P. H. Emmett (ed.), " Catalysis,7 5 M. Greyson, ibid., p. 473.76 S. W. Weller, ibid., p. 513.7 7 H. Steiner, ibid., p. 529.7 8 J . A. Sabatka and P. W. Selwood, J . Anaev. Chem. Soc., 1955, 77, 5790.79 A . M. Rubinshtein, I>. Kh. Freidlin, and N. V. Rorunova, Izvest. Akad. Nauk80 G. Rienacker and hT. Hansen, %. anorg.Chew)., 1956, 285, 283.81 P. B. Weisz, C. D. Prater, and K. n. Rittenhouse, J . Chem. Phys., 1963, 21, 2236.82 I d e m , ibid., 1955, 23, 1965.83 R. G. Haldeinan and P. H. Emmett, J . Anzer. Chem. SOC., 1956, 78, 2917.* These nanies are used to describe a linear relation between the logarithm of theK. Hauffe, ibid., p. 213.C . D. Prater and K. M. Lago, ibi!.,, p. 294.Vol. 4. Hydrocarbon Synthesis, Hydrogen-ation, and Cyclization, Reinhold Publ. Corp., New York, 1956.S.S.S.R., Otdel. khim. Nauk, 1955, 766.frequency factor and the activation energvKEMBA~LL : ADSORPTION AND HETEROGENEOCJS CAiT.-lI,YSIS. 67evacuation at 500” c are in the form of Lewis acids rather than Bronstedacids. They found g4 that the exchange between isobutane and heavy wateron these catalysts passed through a maximum as the water was added tothe catalyst.It appeared that water molecules had to be available in thesurface before the hydrocarbon could undergo activated adsorption. A veryinteresting feature of the results was the high number of deuterium atomspresent in the products although the water-content of the catalyst was low,indicating that deuterium was available to diffuse easily over the surface.The catalytic activities of copper-nickel and copper-palladium alloys forthe para-hydrogen conversion 85 have been shown to decrease slowlyas the amount of copper is increased to 60 atoms yo and then morerapidly.Interest has been maintained in the theoretical interpretation of kineticdata of catalytic reactions.Boudart 86 has defended the use of kineticequations based on Langmuir isotherms although admitting that the surfacesrarely fulfil the basic requirements for Langmuir-type behaviour. M7eller,87on the other hand, advocates the simpler approach of working in terms ofpower dependencies. Kwan 88 also favours this approach because so manysets of adsorption data can be adequately described in terms of rate expres-sions involving a power of the coverage and hence in terms of the Freundlichtype of isotherm. Foss 89 has derived a relation between heat of adsorptionof a reactant and experimental activation energy for a unimolecular reaction]and has emphasized the difficulty in the experimental determination of theorder of the reaction when the activation energy is varying with the pressure.Molinari has discussed the ‘‘ theta rule ” 69 with particular reference tothe exchange between hydrogen and deuterium and has shown that amechanism of induced desorption, in which the heat of desorption is suppliedby the adsorbing molecules will account for the relationship between theconstants of the Arrhenius equation.Vol’kenshtein 91 has given a generaldiscussion of the electron theory of catalysis by semiconductors, pointingout the analogy between a catalyst acting as a giant polyradical and the partplayed by radicals in homogeneous reactions. Horiuti’s school has reporteda determination 92 of the stoicheiometric number for ammonia synthesis at29.5 atm. The method of evaluating the stoicheiometric number from therates of reaction near equilibrium was put forward originally by Horiuti 93and it gives the number of times the rate-determining step has to take placefor the overall chemical reaction to occur.The new work92 confirms thatthe value is two for high pressures as well as low pressures 94 in the synthesisR. G. Haldeman and P. H. Emmett, J . Amey. Chewz. SOC., 1956, 78, 2922.8 5 G. Rienacker and G Vormum, 2. anorg. Chem., 1956, 283, 287.8 6 M. Boudart, Amer. Inst. Chenz. Eng. J . , 1956, 2, 62.S. Weller, ibid., p. 59.88 T. Kwan, J . Phys. Chem., 1956, 60, 1033.89 J. Foss, t h i d , p. 1012.91 F. I;. Vol’ltenshtein, Probleway. Kinetzki i ICafalz-a Akad. Nazrk S . S . S . R . , 1955,92 S. Enonioto, J . Horiuti, and H. Kobayashi, .J.R e s . Iwsf. Cnfalvsis, Hokkaidos3 J. Horiuti, ibid., 1948, 1, 8.94 S. Enomoto and J. Horinti, ibid., 1953, 2, 117.E. Molinari, 2. fihys. Chem. (Frankfuvt), 1966, 6, 1 .8. 79.Univ., 1955, 3, 18568 GENERAL AND PHYSICAL CHEMISTRY.of ammonia and suggests that the slow step must be the addition of hydrogento adsorbed nitrogen rather than the dissociative adsorption of nitrogen.Several papers have appeared involving the use of either stable or radio-active isotopes to determine the mechanism of catalytic reactions. Bond 95has examined the deuteration of ethylene over a number of platinumcatalysts. He showed that all possible deuteroethanes were formed, andexamined changes in the distribution with temperature and composition ofthe gas.Kemballg6 examined the same reaction a t low temperatures onevaporated metallic films and put forward a theory which accounts satis-factorily for the initial distributions of deuteroethylenes and deutero-ethanes and is based on the assumption that adsorbed ethylene andadsorbed ethyl radicals are the important entities on the catalyst surface.Flanagan and Rabinovitch 97p 98 have examined the exchange and isomeriz-ation of trans-[2HJethylene on nickel catalysts. Detailed kinetic resultswere obtained and shown to be in agreement with one of two mechanismsboth involving adsorbed ethyl radicals. Integration of rate equations onthe assumption of stepwise exchange (one hydrogen atom a t a time) gaveexcellent agreement with the experimental observations of the proportionsof the various deuteroethylenes throughout the reactions.Miyahara 99has given an alternative explanation of the product distributions observedby Anderson and Kernball100 in the exchange of ethane with deuteriumover evaporated metallic catalysts. The activity of various oxides for theexchange of hydrogen with deuterium has been correlated with the electronicconfiguration of the metal ions.lOl By the use of radio-isotopes it has beenshown that very little exchange takes place at 500" on aluminosilicatecatalysts between ethane and propane and between ethylene and methane.lo2Also, the exchange between methyl chloride and hydrogen chloride has beenexamined on tungsten surfaces and shown to involve adsorbed chlorineatoms probably reacting with physically adsorbed r n o l e ~ u l e s .~ ~ ~ ~ lo4An important development in technique has been the combination ofvapour-phase chromatography with radioactive counting methods for theexamination of products from complex reactions such as hydrocarbon crack-ing and olefin polymeri~ation.10~ Franklin and Nicholson lo6 have examinedthe decomposition of a number of hydrocarbons on silica-alumina catalysts ;they found that there was a decrease in activation energy with molecularweight which paralleled changes in the ionization potential of the molecules95 G. C. Bond, Trans. Faraday SOC., 1956, 52, 1235.96 C. Kemball, J . , 1956, 735.97 T. B. Flanagan and B. S. Rabinovitch, J . Phys. Chesn., 1956, 60, 724.98 Idem, ibid., p.730.99 K. Miyahara, J . Res. Inst. Catalysis Hokkaido Univ., 1956, 4, 143.100 J. R. Anderson and C. Kemball, Proc. Roy. SOC., 1954, A , 223, 361.101 D. A. Dowden, N. Mackenzie, and B. M. W. Trapnell, ibid., 1956, A , 231, 245.102 B. V. Klimenok, E. A. Andreev, 0. V. Krylov, and M. M. Sakharov, Doklady103 R. Coekelbergs, A. Frennet, and P. A. Gosselain, Bull. SOC. chiw. belges, 1956,104 J. Adam, R. Coekelbergs, A. Frennet, and P. A. Gosselain, J . Chem. Phys., 1956,Akad. Nauk S.S.S.R., 1954, 95, 101.65, 229.24, 1267.5860.105 R. J. Kokes, H. Tobin, jun., and P. H. Emmett, J . Amer. Chem. Soc., 1955, 77,106 J. L. Franklin and D. E. Nicholson, J . Phys. Chem., 1956, 80, 59KEMBALL : ADSORPTION AND HETEROGENEOUS CATALYSIS. 69and they suggested that alkyl carbonium ions were formed via molecule-ion intermediates.Shiba and Echigoya lo7 examined the activity of analuminium oxide catalyst for the polymerization of ethylene and showed thatthe activity follows closely parallel to the extent of adsorption of pyridineon the catalyst when the catalyst is pre-heated at different temperatures.losThe decomposition of ozone has been studied on a number of oxides andthe activation energies correlated with properties of the oxides.log~Kummer ll1 has found no marked differences in activity for the oxidationof ethylene on different crystal faces of silver but the absolute rate of thereaction confirmed Twigg's mechanisrn.ll2Stoddart and Kemball l13 have shown that the main reduction productof acetone at low temperatures over evaporated metal catalysts is propan-2-01 with small amounts of propane on platinum films.The kinetics ofthe reaction have been investigated and the order of activity of the metalsfollows closely the order already established for the hydrogenation ofethylene. The hydrogenolysis of substituted cyclopropanes and cyclo-butanes has been studied over ~ 1 a t i n u m . l ~ ~ The hydrogenolysis of methyl-amine 115 over evaporated metal films is controlled by the rate of fissionof the carbon-nitrogen bond. The subsequent reactions are complex andinclude the rapid formation of ammonia, formation of methane to a smallerextent, formation of dimethylamine and subsequently trimethylamine, anduptake of carbon by the catalysts.In similar studies of cyclohexylamine,the unexpected formation of benzene was observed at 134" on platinum 116but the hydrogenation of the benzene to cyclohexane followed after most ofthe amine had been used up. The Fischer-Tropsch synthesis has beenstudied on cementite as a catalyst 117 and new results have been obtainedon the kinetics of the " 0x0 synthesis " (the addition of carbon monoxideand hydrogen to olefins to form aldehydes and hence other products con-t aining oxygen).Maxted and Josephs119 have examined the poisoning of platinumcatalysts. The complete revival of the catalyst for the hydrogenation ofethylene can be obtained in three ways: (i) evacuation, (ii) circulatinginert gas, or (iii) circulating ethylene. The heats of adsorption of the twopoisons ethyl sulphide and thiophen were determined calorimetrically andthe difference in the initial heats of adsorption attributed to the loss ofresonance when thiophen is adsorbed.C .K.Io7 T. Shiba and E. Echigoya, J . Chem. SOC. Japan, 1955, 76, 1046.lo8 Idem, ibid., p. 1049.loD G. M. Schwab and G. Hartmann, 2. phys. Chem. (Frankfurt), 1956, 6, 56.110 Idem, ibid., p. 7 2 .ll1 J. T. Kummer, J. Phys. Chem., 1956, 60, 666.113 G. H. Twigg, Trans. Faraday SOC., 1946, 42, 284.113 C. T. H. Stoddart and C. Kemball, J. Colloid Sci., 1956, 11, 532.114 B. A. Kazanskii and M. Yu. Lukina, Kataliticheskoe i Okislemie Akad. Nauk116 C. Kemball and R. L. Moss, Proc. Roy. SOC., 1956, A , 238, 107.116 R. L. Moss and C. Kemball, Nature, 1956, 178, 1069.117 J.F. Shultz, W. K. Hall, T. A. Dubs, and R. B. Anderson, J . Amer. Chem. Soc.,118 G. Natta, R. Ercoli, and S. Castellano, Chimica e Iwdustria, 1955, 37, 6.llQ E. B. Maxted and M. Josephs, J., 1956, 264, 2635.Kazakh S.S.R., 1955, 18.1966, 78, 28270 GENERAL AND PHYSICAL CHEMISTRY.4. ION EXCHANGE.Successes in the separation of fission products achieved, for ion-exchangeresins, wide importance as analytical tools. Recently, however, develop-ments in the fundamental aspects of ion exchange have seen the emergenceof the technique as an important branch of physical chemistry. Thus, whilethe analytical interest is still maintained and extended, ion-exchange resinshave found wide application as physical-chemical tools for the study ofelectrolytic solutions.In this respect they have been used, for example, ininvestigations on the nature of complex ions in solution, the electrochemistryof ion-exchange membranes, and the determination of activity and selectivitycoefficients.This Report emphasises the physical-chemical developments of ionexchange, although its more outstanding achievements as an analyticaltool will also be included. Progress in biochemistry, water treatment, soilanalysis, electrochemistry of ion-exchangers, and investigations with in-organic ion-exchangers are only included insofar as they contribute generallyto information or applicability.Extensive reviews have been given by Juda, Marinsky, and RosenberglSchubertJ2 and Thomas and Fry~inger.~ Winter and Buser et aL5 havereviewed advances in the physical chemistry of ion-exchange resins, Ardentheir uses on an industrial scale, and Griessbach their technological future.Information on the adsorption of organic compounds, and ion inclusion, iscovered by Samuelson.* Some other reviews merit consideration in that theypresent a general picture of work and information relating to ion exchange.In 1953, Samuelson’s book lo appeared; it still gives one of the bestsurveys of almost all the physical-chemical approaches to the subject as wellas the analytical.During 1956 a new text-book on ion exchange by Nachodand Schubert l1 was published ; twenty chapters are devoted to technologicaland engineering aspects of ion-exchange practices but a discussion of funda-mental problems, techniques, and operations is also included.Osborn’sbook l2 appeared in 1955. A report of a symposium on the application ofion exchange in water and waste treatment has also appeared.131 W. Juda, J. A. Marinsky, and N. W. Rosenberg, Ann. Rev. Plq)s. Chem., 1953,2 J. Schubert, ibid., 1954, 5, 413.4 S. S. Winter, J . Chem. Educ., 1956, 33, 246.5 W. Buser, P. Graf, and W. F. Grutter, Claimia (Swidz.), 1955, 9, 73.7 R. Griessbach, Chew,.-Ing.-Tech., 1055, 27, 569. * 0. Samuelson, Iva, 1955, 26, 178.9 H. Deueland K. Hutschneker, Chimia (Switz.), 1955,9, 49; R. Griessbach, Angew.Chem., 1955, 67, 606; J. Biichi, J. Pharm. Pharmacol., 1956, 8, 369; R. Kunin and F.McGarvey, I n d . Eng.‘?hem., 1955, 47, 565.1” 0.Samuelson, Ion Exchangers in Analytical Chemistry,” John Wiley and Sons,Inc., Kew York, 1953.11 F. C. Nachod and J . Schubert, “ Ton Exchange Technology,” Academic Books,Ltd., London, 1956.12 G. H. Osborn, “ Synthetic Ion Exchangers. Recent Developments in Theory13 I n d . E72g. Chena., 1955, 47, 46--101.4, 373.H. C. Thomas and G. R. Frysinger, ibid., 1956, 7, 137.T. V. Arden, J . Roy. Inst. Chem., 1956, 80, 122.and Application,” Chapman and Hall, Ltd., London, 1956MXGEE : ION EXCHANGE. 71Ion-exchange Equilibria.-Ion-exchange equilibria being of great practicalimportance have been frequently investigated. In view of the complicatednature of the exchangers, theories and experimental results have often beencontradictory. One author at least l2 regards it as impossible to reviewfully the theories relating to their action.Gregor l4found an extended Donnan theory with use of the Gibbs-Donnan formul-ations to be of great theoretical interest.Others have applied the law ofmass action to describe ion-exchange equilibria, while Walton,15 Jenny, l6and Rothmund and Kornfeld l7 found that simple mathematical equationswith one or more empirical parameters best expressed their behaviour.Walton l8 claimed that almost all the data available on distribution in ion-exchangers fit the Rothmund-Kornfeld equation. In the period reviewedit is clear that different investigators find that one or other of these theoriesis able to fit the data under their conditions, but in many cases approachesdifferent from those above apparently adequately represent the nature ofequilibria ; it is possible to discover an almost inexhaustible list of equationsto satisfy equilibrium requirements.From the Donnan equilibrium Yamabe l9has derived the following equation which is valid for exchange between ionsof valency 1 and 2 :where N and n are concentrations of the ion in the resin and solution, respec-tively.A further derived relation 20where Q and E are the initial amounts of ion in the resin and solution,respectively, N is the solution concentration at equilibrium, n is a constantand A and B denote the ions, is valid for ions of different valency. Agree-ment with Donnan equilibrium calculations was also found by Hutschnekerand Deuel.21 Stewart and Graydon 22 measured cation- and anion-transferrates across various poly(styrenesu1phoiiic acid) membranes and consideredthe anion-transfer rates in terms of a Donnan equilibrium : further evidencefor its applicability, at least in a qualitative sense, was shown 23 duringinvestigation of the effect of dilution on cation-exchange equilibria. InNaCl-HC1 exchange on an Amberlite IR-120 resin, a Donnan equilibriumexists 24 between resin and solution phases.Although it existed also for theLiC1-HC1 system, its validity only extended between concentrations 0 . 1 ~and 0 . 3 ~ ; anomalies in solutions of higher concentration were explainedby assuming the lithium ion to be dehydrated.Some have regarded ion exchange as a Donnan equilibrium.The Donnan equilibrium.NB/nB == (NA/%A)2 .. . . - * (1)(QA + EA) /(CQB + EB) = ~NA./NB . - . (2)l4 H. P. Gregor, J. Amer. Chenz. SOG., 1948, 70, 1293; 1951, 73, 642.l5 H. F. Walton, J. Phys. Chew., 1943, 47, 371.l6 J. Jenny, ibid., 1932, 36, 2219.l7 V. Rothmund and G. Kornfeld, 2. anorg. Chem., 1918, 103, 129.2o Idern, ibid., p. 191.21 K. Hutschneker and H. Deuel, Helv. Chim. A C ~ L C , 1966, 39, 103%).aa R. J. Stewart and W. F. Graydon, J . Phys. Cheiiz., 1956, 60, 750.23 E. Keiner, K. F. Schulz, and B. Tezak, Arkiv Kemi, 1955, 27, 93.24 H. Kakihana, N. Maruichi, and K. Yaniasalri, J. Phys. Chenz., 1966, 60. 36.H. F. Walton, J. Franklin Inst., 1941, 232, 305.T. Yamabe, J. Chem. SOG. Japan, 1955, 58, 91572 GENERAL AND PHYSICAL CHEMISTRY.Empirical equatiorts.A very valuable and interesting contribution hasbeen made by Hogfeldt 25 who investigated empirical equations of Jenny,Rothmund and Kornfeld, Freundlich, Krocker, Vageler, Weisz, van Dranen,Yamabe and Sato, and Boedeker for which validity has been claimed. Mostof the data were derived from AgH exchange on Dowex-50 and Wofatit K8resins. The Freundlich equation alone represented all types of equilibrium-quotient curves, but the most useful equation was that of Rothmund andKornfeld which could be extended in a very simple way to cover all types.Determinations of the parameters of the Rothmund-Kornfeld equationhave been reported from investigations of exchange equilibria on sulphonatedAssam coal.26Davydov and Levit’skii2’ have found that the Vageler, Gapon, andmodified Nikal’skii equations are applicable to the exchange of Caz+, Mg2+,and Ba2+ for K+ and Naf on Wofatit P.The law of mass actiort.An empirical formula based on the law of massaction is suggested by Yamabe 28 to represent the equilibrium in the exchangeOH-C1 on Amberlite IR-400 or -410. For Ag+-H+ equilibrium on WofatitKS at low silver concentrations29 the equilibrium quotient is defined as({H+)[AgR]) /({Ag+}[HR]) where enclosing { ] and [ 3 represent concentrationsin resin and solution respectively. The coefficient KHAg has a constant valueof 0.26 within the limits 7 x and 4 x for the mole fraction of silverin the resin. Validity of the law of mass action for H-Na exchange onAmberlite IR-120 is also reported.30 Hysteretic effects in the exchangeBa-H on a strongly acidic resin made Vanselow’s law of mass action invalidwith respect to the real behaviour of the resin ~hase.~1 For completecharacterization of the exchange, knowledge of the selectivity coefficientfor the resin and the ion pair is necessary.Simple mass-action considerations were not sufficient to explain theelution behaviour of alkaline-earth and alkali metals on cationic resins ofdifferent ~ross-linking.~~It isknown that the resin phase can be conveniently treated as a concentratedaqueous solution.In such a system, a variation of the activity coefficientswill occur with cross-linking. The dependence of selectivity and swellingon cross-linking is understandable 33 by consideration of resins as poly-electrolytic gels with certain properties.Selectivity and activity-coefficientdeterminations 3437 suggest that ion-exchangers must be treated as poly-Activity coeficients, selectivity coeficients, and degree of cross-linking.26 E. Hogfeldt, Acta Chem. Scand., 1955, 9, 151.26 M. Roy, J . Appl. Chem., 1956, 7 , 335.27 A. T. Davydov and I. Ya. Levit’skii, Trudy Nauch.-lssledovatel. Inst. Khim.28 T. Yamabe, J. Chem. SOC. Japan, 1955, 58, 186, 188.29 E. Hogfeldt, Arkiv Kemi, 1954, 7 , 561.30 T. Yamabe, J . Clzem. SOC. Japan, 1954, 57, 701.31 P. M. Stroechi, Ann. Chim. (Italy), 1954, 44, 147.32 R. M. Diamond, J. Amer. Chem. SOC., 1955, 77, 2978.38 F. E. Harris and S. A. Rice, J . Chem. Phys., 1956, 24, 1258.34 G.E. Mayers and G. E. Boyd, J . Phys. Chem., 1956, 80, 521.35 0. D. Bonner, V. F. Holland, and L. L. Smith, ibid., p. 1102.8 6 H. A. Stroebel and R. W. Gable, J.-Amer. Chem. Soc., 1954, 76, 5911.87 J. S . Mackie and P. Meares, Puoc. Roy. SOC., 1956, A , 282, 485.Klzavkov Univ., 1953, 10, 221MAGEE ION EXCHANGE. 73meric n : 1 electrolytes. Determinations of selectivity coefficients, for anion-exchangers38 as a function of resin and degree of cross-linking, and forcation-exchanger~,~~ are presented.Reichenberg and McCauley 40 have studied equilibria on sulphonatedpolystyrene resins of varying degrees of cross-linking. The order of affinitieswas K > Na > H > Li. Gregor's theory of ion-exchange affinity did notaccount for all the results, a modificatiop being necessary to account for thestatistical variation of cross-linking and relative ease with which hydrationshells can lose some water molecules.On methacrylic acid cation-exchangers of various divinylbenzene con-tents the order of affinity was Li > Na > K, becoming more marked ascross-linking increased.41Undoubtedly, many other factors can change the activity coefficients inthe resin phase.Ion-pair formation offers a probable explanation forabnormal behaviour424 and the uptake of electrolyte by the resin is ofsignificance in activity-coefficient determination^.^^, 32The activity coefficients of sodium and potassium chloride have beenmeasured.46 In this respect, an interesting method is reported by Sobueand Tabata43 who carried out measurements on an ion-exchange film ofcarboxymethylcellulose using infrared spectra.The importance of solvent uptake by the resin phase has now beenrecognized and reports of investigations have recently a~peared.~'-~O Inthe uptake of solvent, ion-hydration has always had a somewhat vaguemeaning.Glueckauf and Kitt 51 have, however, now given informationwhich goes a long way towards clarification of the position. By an isopiesticmethod they investigated the absorption of water by polystyrene sulphonatesand determined the adsorption isotherm and enthalpies and entropies ofhydration. From the shape of the isotherms they conclude that the firstwater molecule absorbed by the resin salt is bound to the sulphonate group.Successive water molecules are then bound with the cations.There seems tobe no basis for the suggestion of a definite shell of water molecules about an ion.Determination of the heats of wetting of ion-exchangers with differentionic species on the resin have led to the view that only a few water mole-cules (five for the hydrogen ion; three for the sodium ion) which can becalled " bound water " take part in the hydration of ions.523a B. A. Soldano and D. Chesnut, J . Amer. Chem. SOC., 1955, 77, 1334.39 B. A. Soldano, Q. V. Larson, and G. E. Myers, ibid., p. 1339.40 D. Reichenberg and D. J. McCauley, J., 1955, 2741.41 H. P. Gregor, M. J. Hamilton, R. J. Oza, and F. Bernstein, J . Phys. Chew., 1956,42 M. H. Gottlieb and H. P. Gregor, J . Amer. Chem.SOC., 1954, 76, 4639.43 H. Sobue and Y . Tabata, J . Polymer Sci., 1956, 20, 567.44 H. P. Gregor, J. Belle, and R. A. Marcus, J . Amer. Chem. SOC., 1955, 77, 2713.4 5 E. W. Baumann and W. J. Argersinger, ibid., 1956, 78, 1130.4 6 J. A. Whitecombe, J. T. Banchero, and R. R. White, Chem. Eng. Prop. Synzp.,4 7 B. A. Soldano and Q. V. Larson, J . Amer. Chem. SOC., 1955, 77, 1331.46 0. D. Bonner, J . Phys. Chem., 1955, 59, 719.49 H. Kakihana and K. Sekiguchi, J . Pharm. SOC. Japan, 1955, 75, 111.so H. P. Gregor, D. Nobel, and M. H. Gottlieb, J . Phys. Chess., 1955, 59, 10.51 E. Glueckauf and G. P. Kitt, PYOC. Boy. SOC., 1955, A , 228, 322.62 T. Matsuura, Bull. Chem. SOC. Japan, 1954, 27, 281.60, 263.1954, No. 14, 7374 GENERAL AND PHYSICAL CHEMISTRY.Howe and Kitchener 53 measured the water sorption isotherms for theH-form of polymethacrylic acid resins and claimed that about 0.1 g.ofwater per g. of dry H-resin was very strongly sorbed, indicating hydrogenbonding on the carboxylic acid groups.The Kinetics of Ion Exchange.-FiZm diffasion. An interesting con-tribution to the theory of ion exchange is that based on the supposition thatthe determining step in the process is diffusion through a film of watersurrounding the resin particles. Support for this concept is presented byDickel and Nieciecki 54 who conclude that at low concentrations the rate-determining process in the exchange of alkali-metal ions against hydrogenions on a Levatit SlOO exchanger is diffusion of exchanging ions through awater film of thickness 3 x lo-* cm.Conditions facilitating film formationare reported by Helfferich 55 who measured self-diffusion coefficients anddeveloped an equation which allowed for film formation.Evidence that the exchange of ion pairs of equal valency followed thistype of kinetics is presented 56-58 but, if one of the exchanging ions is eithervery large or held tightly by the resin, diffusion is best described by gel-diffusion kinetics. On the other hand, in the measurement of the self-diffusion coefficient of sodium,59 evidence is presented for the absence ofliquid-film effects. In the absence of a Donnan electrolyte, two mechanismsfor transport through the resin are suggested: an exchange between siteswith an activation energy about 10 kcal./mole and a diffusion involving afree anion with activation energy about 2 kcal./mole.Sugai and Furuichi 60* 61 have reported a study on theself-diffusion of calcium in Dowex-50.In 1M-SOlUtiOnS particle diffusionwas the controlling step : below 0.5111, film diffusion occurred. Tetenbaumand Gregor 62 have carried out investigations with polystyrenesulphonic acidresins which show agreement with the ideas of particle and film diffusion.They measured the self-diffusion of potassium, non-exchangeable chlorideions, and water. At high rates of flow in a shallow-bed system, the calculatedthickness of the unstirred film was 1.2 p. The diffusion coefficients werepotassium 21%, chloride 37%, and water 85% of the value in free solution.Particle-diffusion kinetics are also reported for chloride-molybdateexchange 63 on Amberlite IR-410, where Boyd, Schubert, and Adamson’sequation 64 was applicable at low concentrations ; sodium-hydrogen ex-change 65 on a monofunctional resin with carboxylic acid groups, whereeffective diffusion coefficients of sodium and hydrogen were 3.92 xPa.rticZe diflusion.53 P.G. Howe and J. A. Kitchener, J . , 1955, 2143.54 G. Dickel and L. Nieciecki, 2. Elektrochem., 1956, 59, 913.55 F. Helfferich, 2. phys. Chem., 1955, 4, 386.5 6 C. Khrishnamoorthy and A. D. Desai, Soil Sci., 1955, 79, 159.5 7 Idem, ibid., p. 215.5 8 Idem, ibid., 1953, 76, 307.59 D. Richman and H. C. Thomas, J . Phys. Chem., 1956, 60, 237.6o S. Sugai and J. Furuichi, J .Phys. SOC. Japan, 1955, 10, 1032.61 Idem, J . Chem. Phys., 1955, 23, 1181.62 M. Tetenbaum and H. P. Gregor, J . Phys. Chem., 1954, 58, 1156.63 T. Nomitsu and J. Hironaka, Yumaguchi J . Sci., 1955, 6, 62.G. E. Boyd, J. Schubert, and A. W. Adamson, .J. Amer. Chem. SOC., 1947,69,2818.6B D. E. Conway, J. H. S. Green, and D. Reichenberg, Tram. Faraday SOC., 1954,50, 611MAGEE ION EXCHANGE. 75c1n.2/sec. ; and the adsorption of nicotine 66 on carboxylic and sulphonicacid-type resins.Mackie and Meares 67 derived an equation for the flux of electrolytethrough a water-swollen cation-resin membrane and concluded that ions inthe resin are transported entirely in an internal aqueous phase. At highconcentrations, however, an electrophoretic effect, and at low concentrations,counter-ion binding, introduces error in the flux theory.Evidence that concentration influences the kinetics of exchange hasbeen obtained.Investigation 68 of the effect of concentration of solution,flow rate, and grain size on the rate of adsorption of sodium and calciumions by Wofatit R showed that the exchange of trace amounts proceeded inthe external diffusion region but, as the number of adsorbed ions increased,the process passed over to particle diffusion.Investigation of the ion-exchange isotherms of cobalt and ferrous iron 69led to the proposal of a mechanism consisting of cation difiusion to theadsorption sites (external and particle diffusion), ion exchange adsorption,formation and decomposition of complex ions, and ion movement on thecolumn.S-Shaped curves were obtained 70 for the exchange ofdifferent cations against hydrogen on a bifunctional exchanger.This typeof curve was due to the bifunctionality of the resin but no interaction betweenthe two kinds of group was detected.Tunit’skii et aZ.71 have derived an equation for sorption with a convexsorption isotherm and for the kinetics of linear isotherms an asymptoticsolution has been obtained.72 The central point of the sorption wave wasfound to move with constant speed along the column and the adsorbed ionspread out at sufficient distance from the column inlet proportionally to thesquare-root of the velocity.Investigations of the kinetics of exchange H-Ba and H-Ca on a Wofatitresin showed a parallel advance of the adsorption front whose displacementwas linear with the volume of the solution passed through the column.73From the rates of exchange of sodium and potassium on Dowex 50,Sulfata E t derived an equation with properly selected rate coefficientsto represent the break-through curves.Adsorption curves of 2.2 x 10-5~-CsC1 and 3.5 X 10-2~-SrCI, inhydrogen-ion concentrations of 0,248 and 0 .4 5 ~ have been determined. 75At lower acidities the curves coincide but at higher acidity, strontium isahead of ca3sium.Column kinetics.G6 H. Kawabe, S. Sugimoto, and nil. Yaniagita, Repovt S c i . Res. Inst. (Japuiz), 1954,30’S. Maclrie and P. Meares, PYOC. Roy. SOC., 1955, A , 232, 498, 510.6 8 M. V. Tobbin and F. G. Dyatlovitskaya, Zhur.$2. Khim., 1954, 28, 1539.70 J. 1’. Cornaz and H. Deuel, Helv. Chim. Acta, 1956, 39, 1227.S. Yu. Elovich and N. N. Motorina, ibid., 1956, 30, 69.N. N. Tunit’skii, E. P. Cherneva, and V. I. Andrew, Zhur. $2. Khini., 1954, 28,2006.7 p V. V. Kachin’skii and 0. M. Toiles, ibid., 1956, 30, 407.i3 A. 1’. Davydov, Yu. A. PuIorozova, and M. R. Kogan, T r d y n;aucli.-lssledovufel.74 A. D. Sulfata, J. T. Banchero, and H . K. White, I H ~ . Eng. Cheru., 1955, 47, 2193.litst. Kiaini. Kharkov Univ., 1053, 10, 189.S. XTu. Elovich, Dokladj1 A k a d . Nnuk S.S.S.H., 1955, 101, 29376 GENERAL AND PHYSICAL CHEMISTRY.Freiling 76 has developed a mathematical treatment of the gradient-elution method for column operation, based upon the plate theory andGaussian approximation to the shape of the elution peak.The equationsinvolve a number of limitations. An application of this method is reported 77for the separation of carrier-free activities.Column operating characteristics for three laboratory-prepared resins aredescribed. 78Exchange capacities, sorption of neutral molecules, and secondary processes.Several determinations of the exchange capacity of ion-exchange resinshave appeared.79 Some interesting facts are reported 80 concerning theresidual capacity and leakage of ion-exchangers. For analytical purposes,Amberlite IR-120 and IR-410 are recommended.Amberlite IR-411 (Cl-form) is reported 81 to have the greatest capacityof the strongly basic exchangers for phenol. A mechanism based on hydro-gen bonding between amine nitrogen groups and molecular phenols issuggested to account for the specificity of sorption of phenol by weakly basicion-exchange resins.Molecular sorption alone cannot explain the sorptionof phenols, bases, or aliphatic and aromatic acids by monofunctional cation-exchangers * 82 ionogenic groups present have a significant r61e. The mole-cular adsorption of some organic molecules on strongly basic Dowex 1 and 2,and Amberlite IR-410 has been measured : 83 interference in the chromato-graphic separation can be overcome by the choice of solvent. The sorptionof acetic, propionic, n-butyric, and benzoic acids on sulphonated crosslinkedpolystyrene resin has been shown 84 to be true and uniform and not confinedto the surface of the resin particles.Riickert and Samuelson 85 have investigated the adsorption of sugarson anion and cation resins from ethanol-water.The uptake by desulphon-ated resins was ascribed to the electric field around the ions in the resinphase; adsorption on the higher-polymeric network seemed to be of verylittle importance. The adsorption of glucose on weakly basic anion-exchangers 86 and large organic molecules such as morphine and codeine 87on Russian resins has been reported.Saldadze 88 found complete reversibility for Ba-Mg, K-Ba, and Zn-Cdexchange on a sulphophenolic resin. Absence of reversibility by others isconsidered to be due to secondary processes on the resin, such as reduction7 6 E. C. Freiling, J . Amer. Chem. SOC., 1955, 77, 2067.7 7 W.E. Nervik, J . Phys. Chem., 1955, 59, 681.H. A. Shah and K. P. Govindan, J . Sci. I n d . Res., India, 1956, 14, B, 222;E. B. Byrne and L. Lapidus, J . Amer. Chem. SOG., 1955, 77, 6506.79 S. Fisher and R. Kunin, Ind. Eng. Chem., 1955, 47, 1191; H. P. Gregor, M. J.Hamilton, J. Becher, and F. Bernstein, J . Plzys. Chem., 1955, 59, 874; E. Leclerc andT. Samuel, Bull. Centre belge Etude et Document. Eaux ( L s g e ) , 1956, NO. 31, 23.H. G. Heitmann and K. R. Schmidt, Mitt. Ver. Grosskesselbesitzer, 1954, 32, 360.81 M. G. Chasanov, R. Kunin, and F. McGarvey, I n d . Eng. Chem., 1956, 48, 305.82 S. L. Bafna and K. P. Govindan, ibid., 1956, 48, 310.s3 C. W. Davies and B. D. R. Owen, J., 1956, 1681.84 D. Reichenberg and W. J.Wall, ibid., p. 3364.85 H. Riickert and 0. Samuelson, Svensk kern. Tidskr., 1954, 66, 337.8 6 T. M. Reynolds, Nature, 1955, 175, 46.8 7 N. A. Izmailov and S. Kh. Mushinskaya, Doklady Akad. Nauk S.S.S.R., 1955,8 8 K. M. Saldadze, Kolloid. Zhur., 1954, 16, 284.loo, 101MAGEE ION EXCHANGE. 77and complex-formation. Other secondary processes have been recognizedand investigated 899 and side reactions in the solution and resin phasehave caused difficulties in the measurement of the exchange equilibria ofheavy-met a1 ions. 91Ion Exchange and the Nature of Ions.-Ion-exchange resins have beenused to a very great extent to investigate the nature of ions and propertiesof substances in solution. Reviews have appeared.92By use of anion- or cation-exchange resins, the nature and behaviour ofthe following ion species have been investigated : germanium complexes ofoxalic acid; 93 nickel,94 and niobium 96 chloride complexes ;borates; 97 metal phosphates; 98 citrates of Periodic Group IIA metals; 99tungstates ; loo chromates ; lol and fluorides.lo2An interesting investigation has been carried out by Herber et aZ.lo3 onthe elution of Mn2+, Co2+, Cu2+, and Zn2+ with hydrochloric acid fromsamples of the anion-exchanger Dowex 1 with reference to the cross-linkage,capacity, water content, and elution behaviour of the resin.Kraus and Nelson lo4 have reported results of a series of extensiveinvestigations on the distribution of a large number of elements betweenhydrochloric acid and anion-exchanger, Dowex 1.A very comprehensivereview of this work is given by Thomas and Frysinger lo5 and considerationof it will not, therefore, be repeated here.Evidence exists which suggests that the resin itself can have a part in theformation of some complexes. Investigations of this type are, however,not numerous, but it is probable that they will grow in number becauseknowledge of the r61e played by the resin could be of great importance inthe separation of ion species.Arden and Wood lo6 have found that uranium is sorbed on an anion-exchanger as a complex, U02(S04)3-4, below pH 2.5. The sorption occursby the formation of this ion on the resin. This information has been appliedin the recovery of uranium from its Stokes and Walton lo8 have89 Yu. Yu. Lure and E.S. Peremyslova, Zhur. priklad. Khim., 1954, 27, 1207.9O N. Krishnaswamy, J . Phys. Chem., 1955, 59, 187.91 J. P. Cornaz and H. Deuel, Helv. Chim. Acta, 1956, 39, 1220.92 J. Schubert, ref. 2, p. 437; H. C. Thomas and G. R. Frysinger, ref. 3, 156; J. E.Salmon, Rev. Pure Appl. Chem. (Australia), 1956, 6, 24; V. V. Fomin, Uspekhi Khim.,1955, 24, 1010.g3 D. A. Everest, J., 1955, 4415.94 R. Herber and J. W. Irvine, J . Amer. Chem. SOC., 1956, 78, 905.96 V. V. Fomin, L. N. Fedotova, V. V. Sin'kovskii, and M. A. Andrieva, Zhur. $2.913 J. Ryan and H. Freund, J . Amer. Chem. Soc., 1956, 78, 3020.97 D. A. Everest and W. J. Popiel, J., 1956, 3183.98 A. Holroyd and J. E . Salmon, J., 1956, 269.99 F. Nelson and K. A. Kraus, J . Amer. Chem.SOC., 1955, 77, 801; I. Feldman,100 A. Iguchi, Sci. Papers Coll. Gen. Educ., Tokyo Univ., 1955, 5, 29.101 2. I. Dizdar and 2. D. Draganic, Bull. Inst. Nuclear Sci. Boris Kidrich, 1955,5, 79.l02 G. B. Kauffman, Diss. Abs., 1956, 16, 863.103 R. H. Herber, K. Tonguc, and J. W. Irvine, J . Amer. Chem. Soc., 1955, 77, 5840.104 K. A. Kraus and F. Nelson, ibid., 1955, 77, 4508.106 H. C. Thomas and G. R. Frysinger, ref. 3, p. 156.lo6 T. V. Arden and G. A. Wood, J., 1956, 1596.107 T. V. Arden, J . Roy. Inst. Chent., 1956, 80, 127.108 R. H. Stokes and H. F. VI'alton, J . Amer. Chern. SOC., 1954, 76, 3327.Khian., 1955, 29, 2042.T. Y. Toribasa, J. R. Havill, and W. F. Neuman, ibid., p. 87878 GENERAL ANI) PHYSIC.11, CHEMISTRYinvestigated the stabilities of copper and silver complexes of ammonia onPermutit Q and Amberlite IR-50.On the latter resin they are just as stableas in aqueous solution. Presumably, either the ions are not covalentlybound to the resin sulphonic acid groups or, if they are so bound, the bindingenergy is far less than that between them and ammonia. On the formerexchanger the ammonia complexes are decidedly less stable owing to thegreater tendency to form metal-carboxylate complexes. Confirmation ofthis work is reportedg1 where, on Amberlite IR-50, Cues was found to bemore selectively taken up against ammonia than against [Cu(NH,),I2+.The exchange behaviour of zirconium and hafnium in perchloric acid hasbeen studied.log The results were interpreted on the basis of unhydrolysedmetal species M4 in the aqueous phase at hydrogen-ion concentrations of1~ and 2 M and very low metal-ion concentration.The sorbability of Pb2+ and Bi3+ in chloride and nitrate so1utions,ll0the exchange of sulphate-bisulphate ll1 on Dowex 1-X8, and the ageing offerric oxide hydrosol 112 have also been reported.Ion Exchange in Non-aqueous Systems.-Interest in ion-exchangebehaviour in non-aqueous systems continues to grow.I t is known that therates of diffusion of ions decrease in organic solvents or in mixtures oforganic solvents and water, and reaction on ion-exchange resins would,therefore, generally be slower. Variation in the nature of exchange, how-ever, in these systems makes the subject one of considerable interest.Bergin and Heyn 113 employed cationic-exchange membrane electrodesto nieasure function potentials in liquid ammonia and alcohols.The ratiosof the activity coefficients of ammonium nitrate in liquid ammonia weredetermined and results agreed well with those obtained by different electro-chemical methods.Davies andOwen 114 have reported results for three resins with varying cross-linking.Swelling was said to be directly proportional to the concentration of organiccomponent in the or largely determined by the dielectric constantof the adsorbed solution.l16An excellent report on the kinetics of non-aqueous exchange systems hasappeared.l17 Studies were made by adsorption of butylamine from aqueousethanol on a strongly acidic exchanger. Conclusions drawn were that thereaction rate was independent of the bulk amine concentration and wascontrolled by particle diffusion. Quantitative rules for cation-exchange inmixed media have been suggested.ll* Gable and Stroebel 119 have obtainedSwelling of resins in mixed solvents has been investigated.log E.M. Larsen and Pei Wang, J . Amer. Chem. Soc., 1954, 76, 6223.110 F. Nelson and K. A. Kraus, ibid., p. 5916.112 K. Meguro, T. Kondo, and Y . Hayashi, J . Chem. Soc. Japan, 1955, 76, 482.113 M. J. Bergin and A. H. A. Heyn, J . Amev. Chem. Soc., 1954, 76, 4765.114 C. W. Davies and B. D. R. Owen, .J., 1956, 1676.115 E. A. Materova, Zh. L. Vert, and G. P. Grinberg, Zhur. ohshchei h'hisn, 1954,116 H. P. Gregor, D. Sobel, and M. H. Gottlieb, J . Phys. Chem., 1955, 59, 10.1 1 7 S.Wilson arid L. Lapidus, I n d . Eng. Chem., 1956, 48, 992.118 A. T. Davydov Bnd R. F. Skoblionok, Tvudzr Nazich.-Issledouafel. ITict. K h i m . ,1 1 9 R. W, Gable and H. A. Stroebel, 1. Phys. Chem., 2956, 60, 513R. E. Anderson, W. C. Baumann, and D. I;. Harrington, I n d . Eng. Chern., 1955,47, 1620.24, 953.Khavkov Univ., 1953, 10, 196hIAGEE ION EXCHANGE. 79equilibrium quotients from Na-H, NH4-H, and AgNa exchange in an-hydrous methanol on Dowex 50. Enhanced selectivities are attributed toalterations in the degree of ion-solvation and ion-pair formation. Selectivesorption is reported l20 for cation-exchangers in investigations with water,ethanol, benzene, or mixed non-aqueous systems. By suitable choice of thecomposition of the liquid medium, selectivity of diffusion of individual ionsinto the resin phase can be obtained.Ketones and alcohols with smaller proportions of water and hydrochloricacid have been used 121 for the elution of sorbed copper and nickel on Zeo-Karb 225.The two metals can be separated quantitatively by use ofacetone containing 4% of hydrochloric acid and 10% of water.Barrer and Raitt 122 have investigated the exchange of a large number ofmetal ions on the inorganic ion-exchanger, ultramarine, in organic solventsand Davydov and Skoblionok 123 have found that in the exchange of adsorbedcations on volchonskoite the tendency for Na+ and K+ to displace Ba2+increased as the organic component of the mixed solvent increased.A review of ion-exchange in non-aqueous solutions has recentlyappeared. 12*New and Modified Ion-exchangers.-The preparation of new or themodification of the more conventional resins allows much to be learnedabout the physical processes of ion exchange.It is rather surprising, there-fore, that little attention has, in the past, been given to details of themechanics of preparation. A considerable amount of evidence exists tosuggest that a particle of the normal commercial resin contains a shell ofrelatively high density and a core of comparatively low density and hard-ness. On swelling, internal tensions are produced which cause the resinbeads to crack and exchange properties are thus affected. These facts arerecognised by Abrams 125 who has reported a unique method of polymeris-ation and a new method of sulphonation which gives homogeneous sulphon-ated copolymers of styrene and divinylbenzene possessing properties dis-similar from and superior to those of the standard copolymers.Preparationof resins in which the aim is selectivity is reported. Parrish 12G has preparedselective ion-exchangers from styrene and divinylbenzene. One of theseresins selectively adsorbed mercury : a second showed selectivity towardscopper, nickel, and cobalt between pH 2 and 3.An anion-exchange resin from formaldehyde and melamine for heavy-metal adsorption 12' and another,12* selective for potassium, from raw rubberdissolved in benzene, are reported. Anion-exchangers of selective perme-ability have also been obtained.129 Developments in the production and120 W.Blaszkowska, W. Wisniewski, and A. Teichert, Roczniki Chem., 1955, 29,lZ1 N. F. Kember, P. J. Macdonald, and R. A. Wells, J . , 1955, 2273.121 R. M. Barrer and J. S . Raitt, J., 1954, 4641.123 A. T. Davydov and R. F. Skoblionok, Zhur. obshchei Khinz., 1956, 26, 350.124 L. Sobczyk, Przemysl Chem., 1956, 12, 389.lZ5 I. Abrams. Ind. Eng. Chem., 1956, 48, 1469.126 J. R. Pamsh, Chem. andInd., 1956, 137.12' S. Yoshikawa and T. Kubotera, J . Chem. SOL. Japan, 1954, 5'7, 676.lZ8 H. Nakazawa, J.P. 8196/1954.laS J. T. Clarke, U.S.P. 2,732,35111956.92180 GENERAL AND PHYSICAL CHEMISTRY.study of electron exchangers, first introduced by Cassidy and his co-w o r k e r ~ , ~ ~ ~ are reviewed.131 The ability of seven cation-exchangers toreduce ferric chloride solutions is r e ~ 0 r t e d .l ~ ~ The reduction process isindependent of the ion-exchange process : exchangers produced by co-polymerisation of methacrylic and acrylic acids with different '' bridgeformers " are not reducing agents.Zirconium phosphate is reported 133- 134 to have cation-exchange pro-perties which are excellent for alkali and alkaline-earth metals, ferric iron,and aluminium 133 and, by mixing a solution of zirconium oxychloride witha large excess of sodium tungstate, a cation-exchange material is obtained.135Anions in mercarbide salts ([(CHg30),n+ + n X ' ] , where X' is exchangeable)have been found to exchange in the following orderThe exchange can be reversed by varying the concentration^.^^^Lignins,partly substituted for phenol and formaldehyde in cationic resins containingphenolsulphonic acid, were found to give a more expanded molecularstructure with higher swelling and greater exchange capacity. 138Champetier et aZ.139 have shown that N-diethylaminohydroxypropyl-cellulose has interesting ion-exchange properties. Claims are also made forresins obtained from coalJZ6 by the condensation of vegetable proteins andforma1dehyde,lm from quebracho extracts,141 by surface treatment of silicagel,142 and from agar.143Ion-exchangers as Catalysts.-Catalysts of chemical reactions by ion-exchange resins has reached the stage of development where some accountof its application must be given in a report on progress in ion-exchange.Reviews on the subject have been presented.144 An approach to funda-mentals has been made by Helfferich 145 who treats the pore liquid of theresin in which the reaction occurs as a homogeneous system and comparesit with a homogeneous solution containing electrolyte as catalyst.Cation-exchangers have been used as catalysts in formation of a ~ e t a 1 s . l ~ ~13* H. G. Cassidy, M. Ezrin, and I. H. Updegraff, J . Amer. Chem. Soc., 1953, '75, 1615.131 J. Schubert, ref. 2, p. 416; H. C. Thomas and G. R. Frysinger, ref. 3, p. 151;132 I. P. Losev and A. S. Tevlina, Trudy Komissii Anal. Khim. Akad. Nauk S.S.S.R.,133 K. A. Kraus and H. 0. Phillips, J . Amer. Chew. Soc., 1956, 78, 249, 694.134 C. B. Amphlett, L. A. McDonald, and M. J. Redman, Chem. and Ind., 1956, 1314.136 K. A. Kraus, T. A. Carlson, and J. S . Johnson, Nature, 1956, 177, 1128.137 S. E. Burkat, Ukrain. khim. Zhur., 1955, 21, 669; I. Gdalia, Bull. Res. Council13* A. Scipioni, Ann. Chim. (Italy), 1955, 45, 358.139 E. Champetier, E. Kelecsenyi-Dumeonil, G. Montegudet, and J. Petit, Compt.140 C. Simionescu, E. Calistrii, and D. Feldman, Studii cercetari sti., 1954, 5, 151.141 E. Virasoro, Rev. Fac. Ing. quim., 1954, 23, 51, 59.142 H. Kautsky and H. Wesslau, 2. Naturforsch., 1954, 9b, 569.143 T. Currie, Chem. and Ind., 1955, 116.144 B. A. Lister, I n d . Chemist, 1956, 8, 369; R. Glenat, Chimie et Industrie, 1956, 75,145 F. Helfferich, J . Amer. Chem. Soc., 1954, 5567..146 G. V. Austerweil and R. Pallaud, Bull. SOC. chzm. France. 1954, 1164.NO,- < C1- < Br- < OH- < CN- < I-Ion-exchange materials have been obtained from peat .13'E. B. Trostyanskaya, I. P. Losev, and A. S. Tevlina, Uspekhi Klzim., 1955, 24, 69.1955, 8, 326.A. Weiss and A. Weiss, 2. anorg. Chem., 1955, 282, 324.Israel, 1953, 3, 250.rend., 1956, 243, 269.292MAGEE ION EXCHANGE. 81The action and subsequent reaction depend on the type of compound : formolecules of less than four carbon atoms, reaction stops at the acetal. Withlarger molecules, the olefinic ether is formed. Catalytic action seems todepend on the acid polarity of the exchanger, the position of the polargroups in the macromolecule, and thermostability of the exchanger. Strictdependence on the method of preparation and size of the resin particle isreported 147 in the use of cation- and anion-exchangers as supports forpalladium catalysts during the hydrogenation of maleic acid.Catalysis may also be brought about by acid ~ 1 a y s . l ~ ~Bafna lP9 has studied the catalysis of the acetone-iodine reaction by ion-exchangers as a function of particle size, degree of cross-linking, and concen-tration of acetone, and Mastagli 150 has shown that both types of exchangerscatalyse chemical reactions, independently of one another.Ion-exchange resins have been used catalytically in the de-esterificationof pectin,151 preparation of butyl b e n ~ o a t e , l ~ ~ and hydrolysis of sucrose. 153Ion-exchangers in Analytical Chemistry.-The last Report on this topicwas in 1954. Recently, reviews on the subject have appeared.lM Themain function of ion-exchange resins in analytical chemistry is to makeseparations; the success achieved in this direction is readily seen by thefollowing selection from the literature of the past two years.Details of the use of anion-exchange for the separation of two short-period activities, 207mPb (0.8 sec.) and l 9 1 m I r (4.9 sec.), from long-lived parents207Bi (8 yr.) and lglOs (16 days) are reported.lS5Interest in the separation of the rare-earth elements still continues.Recent advances are characterized by refinements in techniques.156 Thelanthanides and actinides have been separated on Dowex 50-X4 by usingammonium a-hydroxyisobutyrate as eluant.157Excellent work has been carried out by Spedding et al., applying theoreti-cal and practical knowledge of ion-exchange columns to the separation ofnitrogen isotopes on Dowex 50-X12 using sodium hydroxide as e 1 ~ a n t . l ~ ~A separation of radium isotopes, Ra-D, Ra-El and Ra-F, with a radioactivepurity of almost 99.90/, has been obtained.159Ethylenediaminetetra-acetic acid is an eluant of considerable applicationand success. In this capacity, it has been used in the. cation-exchange147 E. Mariani and F. Spinelli, Ann. Chim. (Italy), 1955, 45, 887.148 C. McAuliffe and N. T. Coleman, Proc. Soil Sci. Soc. Amer., 1955, 19, 156.149 S. L. Bafna, J . Chem. Phys., 1955, 23, 1199.lS0 P. Mastagli, Compt. rend., 1956, 242, 1031.151 A. Sato and K. Aso, J . Fermentation Technol. (Japan), 1955, 33, 362.lS2 S. Kitahara and M. Sugihara, Science and Industry (Japan), 1953, 27, 316.153 J. Fodor and 2. Hajos, Magyar Tudomanyds Akad. Ke'm. Tudomdnyok OsztdlyanakKiizlemenyei, 1955, 5. 545.154 R. Pallaud, Chem. Analyt., 1955, 37, 16; 0. Samuelson, ibid., p. 191; 0. E.Schultz, J . Pharw. Pharmacol., 1956, 8, 382 ; J. E. Salmon, Lab. Practice, 1956, 15, 338.155 E. C. Campbell and F. Nelson, J . Inorg. Nuclear Chem., 1956, 3, 233.J. G. Cuninghame, M. L. Sizeland, H. H. Willis, J. Eakins, and E. R. Mercer,ibid., 1955, 1, 163; N. E. Topp, Chem. and Ind., 1956, 1320; W. E. Nervik, J . Phys.Chew., 1955, 59, 690.157 H. L. Smith and D. C . Hoffman, J . Inorg. Nuclear Chem., 1956, 3, 243.158 F. H. Spedding, J. E. Powell, and H. J. Svec, J . Amer. Chem. Soc., 1955, 7'4,6125.*59 T. Tshimori, Bull. Chem. SOC. Japan, 1955, 28, 43282 GENEKAL ANI) PHYSTCAI, CHEMISTRY.separation of barium and lead,160 the preparation of pure cerium earths,161and the anion-exchange separation of the alkali metals. 162A separation of a different type, but still of great interest, is thatclaimed 163 for geometrical isomers of $auo- and croceo-cobalt salts on theNH,-form of Amberlite IR-120. Analysis of the condensed phosphates onDowex 1-X8 is reported 164 and several giving details of theseparation of fluoride from substances which interfere in its colorimetricdetermination, and a method for the determination 166 of atmosphericfluorine, have appeared.Ion-exchange resins’have great versatility : no combination of metalsappears too difficult to separate if the theoretical and practical knowledgeof the exchangers is applied. Thus, the separation of molybdenum andtechnetiurn,l6’ arsenic, antimony, and tin,168 zirconium and hafnium,169zirconium and p r o t a ~ t i n i u i n , ~ ~ ~ rhodium and iridium,171 and niobium andtantalum,172 have all been achieved.Flaschka and Sadek 173 have employed a cationic resin in the deter-mination of potassium by dissolving the precipitate of potassium tetra-phenylboronate in acetone and passing it through the resin : the free tetra-phenylboronic acid liberated is titrated.Chromatography on paper impregnated with ion-exchange resins isreported 174 and preparations of standard solutions of hydrochloric, sulphuric,and nitric acids have been carried out by means of ion-e~changers.~~~R. j. nf.J. H. BAXENDALE.K. 0. COLCLOUGH.C. KEMBALL.R. J. MAGEE.A. D. E. PULLIN.E. WAIIHURST.lGo T. Taketatsu, J . Chem. SOC. Jupaqa, 1955, 76, 756.161 C. Achard, Compt. rend., 1955, 241, 800.lG2 F. Nelson and K. A. Kraus, J . Amer. Chem. SOC., 1955, 77, 813.1G3 11. Mori, M. Shibata, and J . Azami, J . Chein. SOC. Japan, 1955, 76, 1003.164 T. V. Peters and W. Rieman, Analyt. Chim. Acta, 1956, 14, 131.185 \V. FunasakL, M. Kawase, T. Kojima, and Y . Matsuda, Japan Analyst, 1955, 4,514; J . Saulnier, AnaZJtt. Chzwi. Acta, 1956, 14, 62; C. Mader, Chemist-Analvst, 1955,44, 86.3, 49.I c i c J. 1’. Nielsen and A. D. Dangerfield, ilvch. Iwd. Hcalth, 1955, 11, 61.lC7 E. H. Huffnian, R . I,. Oswalt, and L. A. Wjlliams, J . Inorg. Nuclear Chew., 1956,lG8 R. Klement and A. Kuhn, Z . arzalyd. Chem., 1956, 152, 146.K. S. Rajan and J. Gupta, J . Sci. f n d . Res. (India), 1955, 14, B, 453.170 S. Kahn and D. E. Hawkinson, J . Inoiy. Nuclear Chem., 1956, 3, 155.171 M. L. Cluett, S. S. Berman, and I T T . A. E. McBryde, Analyst, 1955, 80, 204.172 AT. J. Cabell and I. Milner, Analyt. Chim. Acia, 1955, 13, 25s.173 H. Flaschka and F. Sadek, Chemist-Analyst, 1956, 45, 20.M. Lederer and S. Kertes, Analyt. China. Acla, 1956, 15, 226.175 C. J. Keattch, Lab. Pmctice, 1956, 5, 208; S. Hirano and M. Kusobe, . J a p m.4nalyst, 1955, 4, 379