|
1. |
Proceedings of the Chemical Society. October 1964 |
|
Proceedings of the Chemical Society ,
Volume 1,
Issue October,
1964,
Page 313-348
Preview
|
PDF (3713KB)
|
|
摘要:
PROCEEDINGS OF THE CHEMICAL SOCIETY OCTOBER 1964 CHRISTMAS COMPETITION 1964 The Editor’s Lament READERS will be aware of the Publications Survey being carried out (Proceedings 1963 73) to deter- mine the pattern of publications required to meet the present and future needs of Chemists. It will also have been noticed (Proceedings 1964 273) that apart from this changes are already being brought about in some of the Society’s monthly periodicals. It seems likely that readers may like to express their own views on the future of chemical publica- tions and are invited to submit them as a contribution to the Christmas Competition in the style of the rhyme “Ten little nigger boys went out to dine One choked his little self and then there were nine” Contributions may begin at any point and rise or descend the numerical scale (depending on the contributor’s view of the future of publications).A prize (book token for two guineas) is offered for the best set of not less than three verses. Entries must reach the Editor (The Chemical Society 20-21 Cornwall Terrace Regent’s Park London N.W.l) not later than December 31st 1964 and may be accompanied by a pseudonym for publication. It is hoped to issue a report in an early issue of Chemistry in Britain. The Editor’s decision will be final. 313 3 14 PROCEEDINGS CENTENARY LECTURE* Applications of Optical Rotatory Dispersion and Circular Dichroh in Stereochemistry By CARL DJERASSI UNIVERSITY CALIFORNIA, (STANFORD STANFORD U.S.A.) THE closely related phenomenal p2 of optical rotatory dispersion (ORD) and circular dichroism (CD) are now sufficiently well known so that an introductory discussion is unnecessary.The first observations’ date to the early part of the nineteenth century yet the real use and familiarity of these methods by the organic chemist is only about ten years old. This is perhaps most dramatically illustrated in Fig. 1 with the very rapid increase since 1955 in the number of publications concerned with applications of optical rotatory dispersion in organic chemistry. This rise coincided with the development in the early fifties of a commercially available spectropolarimetefl and the first publications from our laboratory (1955)4 on organic chemical applications of ORD and from Harvard University (1956)6 on ORD studies in the polypeptide and protein fields.In fact the number of publications in the field have risen so rapidly that the figures for the last three years in Fig. 1 should only -1954 Year FIG.1. Number of publications dealing with organic chemical application of optical rotatory dispersion (1 936-1 963). be considered as approximate as they are based only on my own perusal of the literature. Five years ago it was still feasible for me to present a complete coverage of the place that optical rotatory dispersion was occupying in organic chemistry. In the interim over 700 relevant articles have appeared (see Fig. 1) and it is patently impossible to present even a cursory survey of the progress that has been made.On the other hand a sutficient amount of time has elapsed so that the real role of optical rotatory dispersion and of circular dichroism in organic chemistry has now become clear. The principal applications4 are in the fields of structure determination (e.g. location of carbonyl group in a steroid or triterpenoid) in analytical problems-notably those pertaining to mixtures of isomers,s in the detection of weak or hidden absorp- tion bands and finally in stereochemistry. It is principally through its contributions to stereochem- istry that optical rotatory dispersion (and hence circular dichroism) has passed the iron test of any new physical tool-does it provide information not already available from other sources or methods?-and has found a secure place among the relatively few physical methods which the organic chemist employs in the solution of his research problems.Therefore I shall restrict myself largely to a survey of some of the stereochemical applications of optical rotatory dispersion and to point out what parallel or supplementary role circular dichroism fulfils. In view of the volume of work that has been published in recent years (Fig. l) main emphasis will be placed on studies conducted at Stanford University. The interplay2 among the optical rotatory dispersion circular dichroism and ultraviolet ab- sorption properties of a typical (colourless) organic substance as well as the nomenclature commonly employed in ORD7 and CD8 studies is illustrated * Delivered before the Chemical Society at The University Glasgow on May 26th 1964 at the Imperial College of Science and Technology London S.W.7 on June 11th and elsewhere.For a detailed history see Lowry ,“Optical Rotatory Power,” Longmans Green and Co. Ltd. London 1935. 2 For a recent brief discussion of the relationship between absorption circular dichroism and optical rotatory dispersion see FOSS, J. Chem. Educ. 1963 40 592. a Rudolph J. Opt. SOC.Amer. 1955 45 50. * For leading references see Djerassi “Optical Rotatory Dispersion :Applications to Organic Chemistry,” McGraw- Hill Book Co. New York 1960. 6 For leading references see Blout chapter 17 in ref. 4. For some recent examples see Nakano Hasegawa and Djerassi Chem.Pharm. Bull. (Tokyo) 1963 11 465; Lablache-Combier Levisalles Pete and Rudler Bull. SOC.chim. France 1963 1689; Djerassi and von Mutzenbecher Proc. Chem. SOC.,1963 377. Djerassi and Klyne Proc. Chem. SOC.,1957 55. * Djerassi and Bunnenberg Proc. Chem. Soc. 1963 299. OCTOBER 1964 in Fig. 2 through the positive Cotton effect exhibited by the weak 264 mp transition of the episulphide chromophore in 3p-hydroxycholestan-5a,6a-epi-~ulphide.~ This example also demonstrates a second point which is discussed in more detail below namely that frequently the sign of rotation in the visible (e.g. [ah)is not the same as that of the com- pound’s first Cotton effect (Fig. 2 positive ultra- ,CD positive maximum I\ .+-+ 1 250 300 .350 (my9 FIG.2. Optical rotatory dispersion circular dichroism and ultraviolet spectral curves of 3b-hydroxy-cholestan-Sa,6a-episulphide illustrating current nomenclature practice. violet Cotton effect versus negative rotation in visible). The rotatory dispersion curves in this lecture are expressed in terms of molecular rotation ([+I), while all circular dichroism curves are expressed in molecular ellipticity units ([el). As indicated earlier,a this system has the great advantage for the organic chemist that both properties of the molecule are expressed in terms of parameters which are of the same order of magnitude. Relative Advantages of Optical Rotatory Dispersion and Circular Dichroism.-Prior to the renaissance in the nineteen-fifties only a few rotatory dispersion and circular dichroism measurements had been per- formed on organic substances in the ultraviolet region.The results chiefly due to Lowry,l Kuhn,’O and Mitchel1,ll have been summarised by Klyne.12 While this classical work did not lead to any applica- tions in organic chemistry-principally because in- sufficient examples were examined to permit any generalisation-it demonstrated the feasibility of performing such parallel ORD and CD measure- ments. The reason that the “new era”4 concentrated initially only on optical rotatory dispersion was purely accidental and due to the availability3 of a commercial spectropolarimeter. There is no doubt that if the first commercial instrument had instead been one for the measurement of circular dichroism all of our early studies would have been performed with it.Fortunately this was not the case because it is unlikely that any of the subtleties of optical rotatory dispersion would then have been uncovered. The success of these optical rotatory dispersion ~tudies~#~ stimulated the long dormant interest in improved instrumentation both in terms of new spectr~polarimeters~~ and of devices14 for measuring circular dichroism. One of these circular dichroism instr~rnentsl~~ is in commercial production and a slightly modified version of it was employed in the work discussed below. Now that instruments are available to measure either ORD or CD the question naturally arises what if any advantage one tool has over the other.This question has been answered in some detaiP5 and need only be covered briefly at this stage. For the vast majority of organic chemical applications either method will provide the identical answer and information derived from ORD or CD may be em- ployed interchangeably. An illustration is the recent circular dichroism measurements of some steroidaP and triterpenoidl’ ketones work which essentially duplicates the earlier optical rotatory dispersion studies from our own laboratory on these sub- stance~.~* While not providing any fundamentally new information this repetition of earlier ORD work in terms of CD is useful in that it offers experi- mental support for the prediction that the resulting conclusions must be identical.Thus the octant Djerassi Wolf Lightner Bunnenberg Takeda Komeno and Kuriyama Tetrahedron 1963 19 1547. loInter al. Kuhn and Braun 2.phys. Chem. (Leipzig) 1930 (B) 8,445. l1 Mitchell and Schwarzwald J. 1939 889 and earlier papers. laKlyne in (Raphael Taylor and Wynberg eds.) “Advances in Organic Chemistry,” Interscience Publ. Inc. New York 1960 Vol. I pp. 258-260. l3 For review see Carroll and Blei Science 1963 142 200. l4 (a) Mitchell “Unicam Spectrovision,” 1958 No. 6 6; (b) Badoz Billardon and Mathieu Compt. rend. 1960, 251 1477; (c) Grosjean and Legrand ibid. 2150; (d)Deen D.Sc. Thesis Leiden 1961 ;(e) Holzwarth Gratzer and Doty J. Amer. Chem. SOC.,1962 84 3194; (f)Mason J. 1962 3285. l6 Djerassi Wolf and Bunnenberg J. Amer. Chem. SOC.,1962 84 4552.l6 Velluz and Legrand Angew. Chem. 1961 73 603. l7 Witz Herrmann Lehn and Ourisson Bull. SOC.chim. France 1963 1101. l* Steroids Djerassi et al. J. Amer. Chem. SOC.,1955 77 4354 4359 4364; 1956 78 440 3163 3761 6362 6377. l9 Triterpenoids Djerassi et al. J. Amer. Chem. SOC.,1958 80,4001 ;1959 81,4587. rule,20p21 which was developed exclusively from a large body of optical rotatory dispersion measure ments and which permits a prediction of the sign and often also of the approximate amplitude of the Cotton effect of a ketone is ips0 fact0 applicable to circular dichroism data. Having pointed out the gross similarity of the two physical methods it is now appropriate to draw attention to some of their specific advantages. The most distinguishing characteristic of ORD curves is the operation of background effects i.e.the rota- tional contribution of more distant absorption bands of the same chromophore or of other atoms in the same molecule which may produce variations in shape which are not encountered in circular di- chroism. The contrasting situation is illustrated in Figs. 3 and 4 which contain the ORD and CD PROCEEDINGS prostan-3-one (2) and cholestan-7-one (4) are much more meaningful than their negative CD curves (Fig. 4) which show only some quantitative differences. In this particular group of steroid ketones the background effect is presumably due to varying contributions associated with the T 3T* absorption of the carbonyl group below 200 mp. Such back- ground effects have also been employed to good advantage among twisted biphenylszz and they are responsible for the observation (see Fig.2) that at times the rotation in the visible spectral range is of opposite sign to that of the ultraviolet Cotton effect. One may conclude therefore that for “finger- printing” purposes ORD is to be preferred over CD. In order to impart some distinguishing characteristic to the CD curve measurements have been per- formed23 near the boiling point of liquid nitrogen Circular dichroism 40 30 20 5 -(0 10 = ? of -. z. -10 2. r+ 5< -20 tot h’ 250 300 350 40 hp) FIG.3 FIG.4 FIG.5 FIG.3. Optical rotatory dispersion curves (methanol) of cholestan-3-one (1)) coprostan-3-one (2) cholestan-1-one (3) and cholestan-7-one (4).FIG.4. Circular dichroism curves (methanol) of cholestan-3-one (1)) coprostan-3-one (2) cholestan-1-one (3) and cholestan-7-one (4). FIG.5. Circular dichroism curves (EPA) of cholestan-Zone at 25” and -192”. curves of four isomeric steroid ketones. While the CD curves (Fig. 4) can only be positive or negative the operation of background effects in the ORD curves (Fig. 3) lend sufficient “personality” to the curves that their characteristic shapes can be used without difficulty for characterisation purposes. Clearly the differences in the ORD curves of co-since such conditions have been shown24 to produce increased vibrational structure in the CD curve. This approach shows considerable promise since the acquired fine structure (see for instance Fig.5) differs in a diagnostically significant manner in several of the keto-steroids examined. The existence of background effects in ORD and 2o Moffitt Woodward Moscowitz Klyne and Djerassi J. Amer. Chem. SOC.,1961 83 4013. 21 Djerassi and Klyne J. 1962 4929; 1963 2390. 22 Mislow Bunnenberg Records Wellman and Djerassi J. Amer. Chem. Soc. 1963 85 1342. 23 Wellman Records Bunnenberg and Djerassi J. Amer. Chem. SOC.,1964 86 492. 24 Wellman Bunnenberg and Djerassi J. Amer. Chem. Sac. 1963 85 1870. OCTOBER 1964 their absence in CD is an advantage for structural work but a disadvantage in calc~lations~~ of rota- tional strengths. While such calculations are generally not performed in standard organic chemical work rotational strengths are of considerable interest for theoretical investigations and for such purposes the CD curve is definitely to be preferred.In organic chemical studies when it is desirable to express a Cotton effect in quantitative terms and only the ORD curve is available then instead of somewhat laborious calc~lations~~ of the rotational strengths the molecular amplitude (difference in molecular rotation between peak and trough divided by 100) of the appropriate Cotton effect may be employed21 to good effect. Another area where CD may offer advantages over ORD may be in instances of overlapping absorption bands of which a pertinent example is given in Fig. 6. Earlier ORD measurements26 have -12 -I4 200 FIG.6.Optical rotatory dispersion curves (dioxan) of 17a-and 17p-pregna- 1,4-diene-3,2O-dione and cir- cular dichroism curve (dioxan) of 17p-isomer. shown that steroidal 1,4-dien-3-ones exhibit a very weak negative multiple Cotton effect in the 380-340 mp region which is also reflected in their CD curves.27 Saturated steroidal 20-keto-steroid.s,2* on the other hand exhibit a powerful Cotton effect (first extremum -310 mp),which is positive in the naturally occurring 17/?-series but of opposite sign in the 17a-epimers. This characteristic ORD feature has been used29 to good advantage in stereochemical assignments at C-17 of various 20-keto-steroids. Recently a series of 17a-20-keto-steroids became available30 including 1 7 a-pregna- 1,4-diene-3,20-di- one and its 17p-epimer the ORD curves of which are reproduced in Fig.6. The oppositely signed Cotton effects in the 310 mp region associated with the 20-keto-group dominate the picture and serve as secure means of stereochemical differentiation at C-17. The contribution in the 380-340 mp range of the 1,4-dien-3-one chromophore known to be is practically obliterated since it is hidden under the descending tail of the powerful 310 mp Cotton effect. For comparison the CD curve of the 17@-isomer is also included in Fig. 6 from which the presence of both chromophores is clearly recog- nisable. A similar situation has recently been en- countered31 in an ORD study of some C-13 epimeric androsta-l,4-diene-3,17-diones,where the Cotton effect of the cyclopentanone essentially swamped out the contribution of the 1,4-dien-3-one moiety.It would be incorrect to assume that contributions from overlapping absorption bands are always more readily discerned by CD than by ORD. The opposite \ ,' ONW 0 I I I\ I 300 350 400 450 4.u> FIG.7. Optical rotatory dispersion circular dichroism and ultraviolet spectral curves of cholestan-3a-01 nitrite in dioxan-pyridine (500 1). 25 Moscowitz chapter 12 in ref. 4. 26 Djerassi Riniker and Riniker J. Amer. Chem. SOC.,1956 78 6377. 27 Tschesche Morner and Snatzke Annalen 1963 670 103. z8 Djerassi Bull. SOC.chim. France 1957 741 ; Djerassi Halpern Halpern Schindler and Tam Helv. Chim. Acta, 1958 41 250.28 Crabbe Tetrahedron 1963 19 51. 30 Rubin and Blossey Steroids 1963 1 453 and unpubtished studies. 31 Urech Vischer and Wettstein Helv. Chim. Acta 1963 46 2788. situation is en~ountered~~ in cholestan-3 a-01nitrite (Fig. 7) where the multiple Cotton effect of the ORD curve is better defined than that of the corresponding CD curve. Finally a third problem of overlapping absorption bands should be noted in which only CD will offer an unambiguous answer. An example is (+)-1,2-di- selenane-3,6-dicarboxylic acid,15 whose ultraviolet absorption CD and ORD curves are reproduced in Fig. 8. The CD curve consists of three clearly recog- I I I I -Id220 250 300 350 400 (my) FIG.8. Optical rotatory dispersion circular dichroism and ultraviolet spectral curves of (+)-1,2-diselenane- 3,6-dicarboxylic acid in dioxan.nisable Cotton effects of alternating sign centred at 351 277 and 249 mp. The corresponding maxima in the ultraviolet spectrum are only very poorly de- fined thus demonstrating the great advantage of CD for uncovering hidden absorption bands. If we now examine the corresponding ORD curve we note that the first (positive Cotton effect) centred near 350 m,u is equally decisive as far as that particu- lar transition of the diselenide is concerned. How- ever it is very difficult to determine whether the positive ORD extremum at 255 mp is the peak of a positive Cotton effect corresponding to the 249 mp transition or of a negative Cotton effect centred at 277 mp.If the latter is the case then the troughs of the positive 351 mp and negative 277 mp Cotton effects must have collapsed into one negative ex- tremum due to overlap. That this is actually the case is only clearly demonstrated by the CD curve. Similar difficulties have been encountered in N-phthalimido-derivativesof amines and amino-PROCEEDINGS ____----L /---0 -8-/ u I 5-16-/’ I1 = I1 ’ ‘ -24-1 \; -32-\A/-(2)+) -40-‘1 ,b ,I u 1 FIG.9. Optical rotatory dispersion curves (methanol) of 4a-ethylcholestan-3-one (3) and of degradation product (2) of cafestol(1). Some Recent Applications in Stere0chemistry.-(a) Determination of Absolute Configuration. The assignment of absolute configuration has always been an intriguing problem for the organic chemist.In recent years notably in the natural products field it has become essential because of its direct per- tinence to biosynthetic considerations. This is an area where optical rotatory dispersion has found immediate and widespread acceptance because of the urgent need for new and rapid methods for the determination of absolute configuration. The original workM concentrated on the carbonyl chromophore and was based on the experimentally documented fact that the sign of the Cotton effect of a given ketone was dominated by its immediate environment-in polycyclic systems the surrounding bicyclic framework. Provided no conformation changes are operative (vide infra) then all that is required is to compare the rotatory dispersion curve of a model ketone (e.g.a steroid) of known absolute 32 Djerassi Wolf and Bunnenberg J. Amer. Chem. SOC.,1963 85 2835. Wolf Bunnenberg and Djerassi Chem. Ber. 1964 97 533. 34 Djerassi Riniker and Riniker J. Amer. Chem. SOC.,1956 78 6362. OCTOBER 1964 configuration and identical bicyclic environment as the unknown ketone with the latter’s dispersion curve. The method has been used with telling success in a wide variety of instances35 and a single example- the determination of the absolute configuration of cafest01~~~ should suffice to illustrate its operation. The furan ring of cafestol (1 Fig. 9a) was trans- formeda6 into the ethyl ketone moiety of (2) and the latter’s rotatory dispersion curve compared with thatN of 4a-ethylcholestan-3-one (3).Since the two Cotton effect curves were of mirror image (Fig. 9) it follows that cafestol possesses the antipodal absolute stereochemistry of the A/B ring juncture a result which was most unexpected although in the interval many other examples of such antipodal terpenoids have been uncovered by optical rotatory dispersion measurements. The simplicity of this approach should be contrasted with the difficulty which would have been encountered if this con- figurational problem would have had to be solved by classical chemical means. Since only the sign and approximate amplitude of the Cotton effect associ- ated with the carbonyl chromophore is used as a guide circular dichroism measurements cm be employed with equal facility.This approach is of course not limited to the carbonyl group. The only reason why this chromo- phore was selected for much of our initial work4 is that its n -n* absorption occurs in a convenient spectral range with low extinction; furthermore it is one of the most common functional groups in organic chemistry especially if one considers that alcohols are readily oxidised to the corresponding ketones. In more recent years we have developed the con- cept of “chromophoric derivatives” in which a “transparent”* functional group is transformed into a derivative which absorbs in a more accessible spectral range. Such work is of intrinsic interest since it offers information on the optical and spectral behaviour of new chromophores and it also serves to demonstrate whether their ORD or CD curves lend themselves to stereochemical conclusions.In Table 1 are listed the functional groups and chromo- phoric derivatives which have been investi-gated15*32t33p3747 in our laboratory together with the 0 d x 10 20 15 -15 0% -20 I * 5 1 FIG. 10. Optical rotatory dispersion circular di- chroism and ultraviolet spectral curves of N-phthaloyl-2QP-amino-5 a-pregnan-3/3-01 in dioxan . * It should be recalled that “transparent” is a relative term and depends largely on the status of the instrumental art. Chromophores such as the carboxyl group which were considered “transparent” a few years ago can now be shown (see Klyne Scopes and Jennings XIX I.U.P.A.C.Congress London July 1963 Abstracts p. 110) to exhibit Cotton effect curves by using spectropolarimeters which can penetrate further into the ultraviolet. s6 For leading references see chapter 10 in ref. 4 as well as Djerassi Pure and Appl. Chem. 1961,2 475. 36 Djerassi Cais and Mitscher J. Amer. Chem. Soc. 1959 81,2386. s7 Sjoberg Fredga and Djerassi J. Amer. Chem. SOC.,1959 81,5002. Djerassi Lund Bunnenberg and Sheehan J. Org. Chem. 1961 26,4509. Djerassi Lund Bunnenberg and Sjoberg J. Amer. Chem. SOC.,1961 83,2307. ** Djerassi Undheim Sheppard Terry and Sjoberg Actu Chem. Scand. 1961 15,903. I1 Unpublished experiments with A. Kjaer (Copenhagen) and B. Sjoberg (Uppsala). IaDjerassi Harrison Zagneetko and Nussbaum J.Org. Chem. 1962 27 1173. 4s Sjoberg Cram Wolf and Djerassi Acfa Chem. Scund. 1962 16 1079. 44 See also Sjoberg Karlen and Dahlbom Acfu Chem. Scund. 1962 16 1071. 46 Djerassi Undheim and We!dler Actu Chem. Scund. 1962 16 1147. I6 Unpublished experiments with J. Burakevich. 4’ Bunnenberg and Djerassi J. Amsr. Chem. SOC.,1960 82,5953. PROCEEDINGS TABLE 1. Functional Chromophoric group derivative -NHSa -NHC( =S)SR -NHSa :NH NNO -NHCOR N(N0)COR RCHC02H I NH2 I C6H5 RCHCO2H RCHC0,H I I NH2 NHC( =S)OC2Hs RCHC0,H RCHC02H I I NH2 NHC( =S)C6H5 RCHC02H RCHC02H I I NH2 NHC( =S)CH&Hs -OH -OC( =S)SR -OH -ON0 -C02H -CONHC( =S)NR2 -CO2H -C(=S)NRR' -c=c-4-C-S SAS 1 I 4=C-44- -c=c-c-c-I I 0 0 \/ 0s // \o 0 Also applicable to a-amino-acids.Absorpt. max. (mp) 330 300 370 350-450 310 280 380,290 335,270 350 325-390 340 3 25-3 60 260 235,305,430 450 550 Ref. 15,37 33,38 39 39 15 40 15 40 41 44 41 44 15 37 42,43 32,42 15,45 46 9 9 47 OCTOBER 1964 321 position of the optically active absorption band(s) by means of ORD or CD is a profitable area of of these derivatives. In most instances the sign of research which is bound to expand considerably.= the Cotton effect of the “chromophoric derivative” Of even broader range for absolute configurational could be related to the absolute configuration of the assignments is the octant rule20e21 and some of its adjacent asymmetric centre in spite of the fact that extensions 59160 since once the scope of the rule has free rotation is possible around the bond connecting been established model compounds of known the substituent to the asymmetric carbon atom.absolute configuration are not required any more. Further comment on this point will be made below The rule predicts the sign of the rotational contribu- in the section dealing with free rotational isomerism. tion of various substituents in a ketone and its quali- With the exception of the osmate complexes (last tative use has been of great importance for absolute entry in Table l) all the chromophores listed in configurational work.61 By establishing quantitative Table 1 have been subjected to parallel ORD and values for some of the more common substituents CD measurements and as anticipated the stereo- (e.g.methyl,s2 isopropyl,s3 t-butyP4) through the chemical conclusions were identical. Consequently synthesis of appropriate model compounds the no particular advantage accrues to either method amplitude of a given ketone’s Cotton effect can when employed for such stereochemical purposes. frequently be predicted21 and thus used for more In a number of instances the ORD and especially subtle conformational conclusions (vide infra). Until now the octant rule has been used only in ketones the CD measurements have uncovered hidden transi- but a priori there is no reason why similar generalisa- tions which were not detectable by ordinary ultra- violet spectroscopy.This subject is outside the scope tions cannot also be made for other chromophores of the present lecture but one recent example may (cf. ref. 56) where the geometry of the relevant be cited in Fig. 10 in terms of the ultraviolet ORD transition is well understood and CD curves of N-phthaloyl-20/3-amino-5a-(6) Applications to Con formational Analysis. The The ORD and especially the CD birth and early development in England of con- pregnan-3p-01.~~ curves show two closely spaced negative Cotton formational analysis in organic chemistry65 make it effects at 332 and 318 mp which correspond to particularly appropriate to consider in this lecture transitions that are completely hidden in the ultra- the role which ORD and CD play in this area of violet spectrum under the strong 293 mp absorption stereochemistry.The enormous potential of ORD in band. Similar observations have been made in our conformational analysis and the sensitivity of the laboratory in a number of instances while conducting method to even slight conformational alterations ORD and CD studies on non-ketonic chromophores was recognised quite early in our ~ ~ r k In . ~ ~ such as biaryls22~4830 disulphides the intervening years so many papers have been and ap~rphines,~~ and di~elenides,~~~~~ a-i~do-ketones,~~published on the detection or description of con- trithi~nes,~~J” azides,66 thi~cyanates,~~ formational changes by means of optical rotatory aliphatic nitro-comp~unds,~~ ethylene thi~ketals,~~ This un- dispersion that it is impossible to provide even a and thi~lacetates.~’ covery of hidden or overlapping absorption bands cursory review of the subject within the confines of 48 Mislow Glass Happs Simon and Wahl J.Amer. Chem. SOC.,1964 86 1710. 40 Mislow Glass O’Brien Rutkin Steinberg Weiss and Djerassi J. Amer. Chem. SOC.,1962 84 1455. 60 Bunnenberg Djerassi Mislow and Moscowitz J. Amer. Chem. SOC.,1962 84 2823 5003. 61 Djerassi Mislow and Shamma Experientiu 1962 18 53. 62 Djerassi Fredga and Sjoberg Actu Chem. Scand. 1961 15,417. 69 Djerassi and Luttringhaus Chem. Ber. 1961 94 2305. 64 Wolf Bunnenberg Djerassi Luttringhaus and Stockhausen Annulen 1964 in the press. 66 Djerassi Wolf and Bunnenberg J. Amer. Chem. Soc.1963 85 324. Unpublished experiments with K. Ponsold (Jena) and A. Moscowitz (Minneapolis). 67 Unpublished experiments with D. A. Lightner and K. Takeda (Osaka). 68 For recent illustrations see Weiss and Ziffer J. Org. Chem. 1963 28 1248; Yang and Samejh J.Amer. Chem. SOC.,1963,85,4039. 50 Djerassi and Klyne J. Amer. Chem. SOC.,1957 79 1506. 60 Moscowitz Mislow Glass and Djerassi J. Amer. Chem. SOC.,1962 84 1945. 61 For a typical example see Djerassi Quitt Mosettig Cambie Rutledge and Briggs J. Amer. Chem. SOC.,1961 83 3720. 62 Beard Djerassi Sicher Sipos and Tichy Tetrahedron 1963 19 919. 63 Djerassi Hart and Beard J. Amer. Chem. Sac. 1964 86 85. 64 Djerassi Hart and Warawa J. Amer. Chem. SOC.,1964 86 78. 85 Inter al. Barton Experientiu 1950,6 316; J.1953 1027; Barton and Cookson Qzrurf. Rev. 1956,10,44; Barton and Morrison in (Zechmeister ed.) “Progress m the Chemistry of Organic Natural Products,” Springer Verlag Viema 1961 Vol. XIX pp. 165-2410 66 Djerassi and Marshall J. Amer. Chem. SOC.,1958 80 3986. 67 Djerassi and Geller Tetrahedron 1958 3 319. the present lecture. I shall therefore limit myself to a few selected examples which should illustrate the scope and trend of current research in the field. If I were asked to specify the single most important con- tribution of optical rotatory dispersion (and hence also of circular dichroism) I would point to con- formational studies as the answer. The justification is perhaps best given by a simple example. The carbonyl group in the chair form (I) of cyclo- hexanone is an intrinsically symmetric chromophore.(+)-3-Methylcyclohexanone (11) exhibitP a positive Cotton effect owing to asymmetric perturbation of the electrons involved in the n -v* transition of the symmetric carbonyl chromophore by the partially unshielded nuclei of the methyl substituent which in the chair form (11) is situated in a positive octant.20 In the alternate chair form (111) the only asymmetric substituent-the methyl group-is now located in a negative octant and a negative Cotton effect would be predicted. Finally in the twist form (IV) the cyclohexanone ring itself becomes asymmetric and the additional contributions of carbon atoms 3 and 5 which reside in positive octants as does the methyl group lead to the predi~tion~~ that IV should display a very much stronger positive Cotton effect than 11.Intermediate forms between the extremes encom- passed by 11 111 and IV would then give Cotton effects differing either qualitatively (sign) or quanti- tatively (amplitude) from those of 11 111 and IV depending upon the relative juxtaposition of the various asymmetric atoms vis-a-vis the carbonyl chromophore. The same situation will be en-countered in more complex molecules except that the contribution of additional substituents has to be reckoned with. The effect of these additional asym- metric substituents decreases rapidly with distance and this explains why generally only the bicyclic environment around the carbonyl group in poly- cyclic systems needs to be taken into consideration in a qualitative prediction of the sign of the Cotton effect for absolute configurational purposes (vide supra).With this picture as a background we may now consider a few actual examples from the litera- ture where ORD and CD were employed in problems of conformational analysis. PROCEEDINGS The first e~arnple’~ shows the demonstration by means of ORD of an anticipated conformational change produced by an equatorial methyl group. The approximate rotatory contribution of an equa- torial methyl substituent /3 to a carbonyl group in a cyclohexanone can be derived from the Cotton effect amplitude (a)21 of (+)-3-methylcyclohexanone which may be expected to exist largely in the chair form (11).This value a -25 when added to the experimentally determined value a = -27 for (-)-trans-9-methyl-l -decalone (V) leads to a pre-dicted amplitude of -52 for (-)-3,9-dimethyl-trans-l-decalone (VI) which is in excellent agree- ment with the experimentally determined Cotton effect. We conclude therefore that introduction of an equatorial methyl group into the C-3 position of (V) does not produce conformational distortion. However when the same simple arithmetic operation is performed with 5 a-androstan-17/3-01-%one acetate (VII) and its lg-methyl homologue (VIII) a calculated value of a = f29 is obtained for (VIII) which is in marked contrast to the observed amplitude of +72. The origin for this serious dis- crepancy appears to be the non-bonded interaction easily seen from an inspection of models between the equatorial lp-methyl and 11 a-hydrogen sub-stituents which can relieve itself most readily by conformational distortion of ring A.Either a boat form (with C-2 and C-5 the prow and stern) of ring A or the corresponding twist form (with C-3 and C-10 the “points”69) would relieve this interaction and at the same time move the lj?-methyl group from a negative to a positive octant. (v);R=H (VI I) R-H (VI) ,R=Me (Vl II),R=Me The second example’l illustrates how rotatory dis- persion measurements uncovered an unexpected conformational phenomenon for which there existed no precedent. One of the long outstanding problems in conformational analysis is the conformation of the cis-2-decalones for which two all-chair forms are feasible-the “steroid” conformation (IX) and the “non-steroid” form (XI.Originally,72 it had been 68 French and Naps J. Amer. Chem. SOC.,1963 85 2303; Djerassi and Krakower ibid. 1959,81 237. 69 Djerassi and Klyne Proc. Nut. Acud. Sci. U.S.A. 1962 48 1093. 70 Djerassi Lund and Akhrem J..Amer. Chem. SOC.,1962 84 1249. 71 Djerassi Burakevich Chamberlin Elad Toda and Stork J. Amer. Gem. SOC.,1964 86 465. Klyne Experienfia 1956 12 119. OCTOBER1964 suggested that cis-10-methyl-2-decalone exists in the “non-steroid” form (Xa) while the opposite con- clusion was reached66 from a comparison of the ORD curves of optically active cis- lO-methyl-2- decalone and 5/3-3-keto-steroids which must exist in the “steroid” conformation because of the addi- tional B/C ring juncture.In any event the energy difference between IXa and IXb was predicted73 to be quite small. A much more unambiguous case seemed to be cis-7,7,1O-trimethyl-2-de~alone,~~ where an addi-tional methyl-methylene interaction is introduced in the “steroid” form (IXb) which is absent in the “non-steroid” counterpart (Xb). The very reasonable conclusion was drawn73 that the trimethyldecalone exists almost completely as Xb. This deduction can be tested easily in the optically active ketone by means of optical rotatory dispersion since the octant rule20 would predict a strong positive Cotton effect for Xb-all substituents being in positive octants- while a very weak or negligible Cotton effect should be exhibited by the “steroid” conformation IXb since virtually all contributions cancel out.When the optically active form of cis-7,7,1 O-trimethyl-2- decalone was ~ynthesised,~~ the surprising observa- tion was made that the substance showed only a very slight Cotton effect which definitely rules out the anti~ipated~~ “non-steroid” conformation (Xb). While the ORD results would be compatible with the alternate “steroid” conformation (IXb) this can certainly be eliminated on energetic grounds because of the unfavourable methyl-methylene interaction. Evidently one or more flexible forms are involved- a conclusion which would not have been reached in the absence of ORD measurements.(IXa):R-H (IXb):R=Me A third e~ample~~p~~ covers the demonstration of conformational mobility in trans-2-chloro-5-methyl-cyclohexanone (XI) by 0RD67174and CD24y75 measurements. The octant rule20p59 predicts a posi- tive Cotton effect for the diequatorial form (XIa) (Fig. 11) and a strongly negative one for the diaxial conformation (XIb) of trans-2-chloro-5-methylcyclo-hexanone. As shown in Fig. 11 the Cotton effect is FIG.11. Optical rotatory dispersion curves of trans-2-chloro-5-methylcyclohexanone(XI) in methanol and iso-octane. indeed positive in the polar medium methanol but becomes negative when iso-octane is employed as solvent. This result suggests the presence of an in- creased amount of the diaxial form (XIb) in the non- polar solvent in accord with predi~tion~~ about the effect of solvent polarity upon the conformer equi- librium in a a-halogenocyclohexanones.By esti- mating the quantitative contribution of an axial a-chlorine atom from steroid models it is possible to ~alculate’~ an approximate amplitude value for the pure diaxial form (XIb) and thus to determine the approximate percentage of the conformers in methanol (99 % XIa) and iso-octane (-82 % XIa).The problem can also be attacked by circular dichroism measurements (Fig. 12) where changes in solvent polarity24 or in temperat~re~~.~~ affect the conformer equilibrium. In fact it has been shown7’ that from the temperature-dependent CD measure- ments it is possible to calculate the relative con- former populations with a considerably greater degree of accuracy thus showing that in methanol there is present 97 & 2% diequatorial isomer (XIa) compared to 89 f3% in iso-octane solution.In spite of the fact that the two conformers XIa and XIb absorb over 20 mp apart the ultraviolet absorp- 73 Halsall and Thomas J. 1956 2431. 74 Djerassi Geller and Eisenbraun J. Urg. Chem. 1960 25 1; Allinger Allinger Geller and Djerassi ibid. 1961 26 3521. 76 Moscowitz Wellman and Djerassi Proc. Nat. Acad. Sci. U.S.A. 1963 50 799. 76 Allinger and Allinger Tetrahedron 1958 2 64. 77 Moscowitz Wellman and Djerassi J. Amer. Chem. SOC.,1963 85 3515. PROCEEDINGS n-FIG.12. Circular dichroism curves of trans-Zchloro-5-methylcyclohexanone (XI) in carbon tetrachloride (25") iso-octane (25") and EPA (25" and -192").ti on spectrum of trans-2-chlor o-5-me t hylcyclo- hexanone exhibits only a single broad hump (due to overlapping) in the 290 mp region. The presence of the two species however is clearly discernible in the CD curve (Fig. 12) principally because the two contributions though strongly overlapping are of opposite sign. A change in sign of the Cotton effect does not necessarily denote a conformational equilibrium. A number of conformationally rigid molecules (e.g. isofenchone exhibit this phenomenon which has been a~cribed'~.~~ to asymmetric solvation i.e. varying mixtures of solvated and non-solvated species. We may consider in some detail the case of (-)-menthone (XIII) where conformational mobi- lity as well as asymmetric solvation can be shownso to operate.In Fig. 13 are summarised some of the solvent- dependent circular dichroism measurements that have been performed with (-)-menthone (XIII). A priori the very substantial difference in wavelength (ca. 30 mp) between the positive and negative maxima in any given solvent might be construed to mean that we are not dealing with a simple equi- librium between the unsolvated diequatorial form ,'.J* :. I I I "\...-\' \I \I -4 L* FIG.13. Circular dichroism curves of (-)-menthone (XIII) in methanol acetonitrile methylene chloride dioxan and iso-octane. effect^.^^^^^ The basis for such a conclusion would be that there exists no obvious reason why such a con-formational change should cause such a large wave- length change; in fact a pair of equatorial-axial steroidal isomers (XVI vs.XVIP3) exhibited a maximal difference in their individual CD maxima of only 3-5 mp. However a recent calculations0 has shown that superposition of two oppositely signed CD bands differing in the location of the respective maxima by only 1 mp can give rise to the type of "double-humped" curve seen in Fig. 13 in which the two maxima are separated by as much as 28 mp.A consequence of this superposition is that the amplitude of the resulting double CD signal is very much weaker than that of the individual com- ponents. In other words even two conformers differ- ing in their CD maxima by a very small value (-1 mp) can cause the effect shown in Fig.13 which therefore need not necessarily be associated with solvation. ;+-ve-( (XI IIa) (XI I I b) (Xlllc) XIIIa (predictede3 to be weakly positive) and the un- solvated diaxial chair (XIIIb) or twist (XIIIc) forms If we now examine the temperature-dependent both of which should show strong negative Cotton circular dichroism of (-)-menthone in a hydro-7a Gervais and Rassat Bull. SOC.chim. France. 1961 743. 70 Coulombeau and Rassat Bull. SOC.chim. France 1963 2673. *O Unpublished experiments by Laur Briggs Moscowitz Djerassi and Wellman. OCTOBER 1964 carbon mixture (5 :1isopentane-methylcyclohexane) we note (Fig. 14) a red shift upon lowering the LI 1 240 340 (my4 FIG.14.Circular dichroism curves of (-)-menthone (XZIZ) in 5 :1 isopentane-methylcyclohexane at 25" -74" and -192". temperature to -192" as well as a major increase in rotational strength in going from -74" to -192" as compared to the +25" to -74" range. This sub- stantial increase in the positive CD curve upon drastic lowering of the temperature is in agreement with an increase in population of the diequatorial I 3l 2 cy 0 X n .8. FIG.15. Circular dichroism curves of (-)-menthone (XIII) in decalin at +162" +25" and -74". conformer XIIIa and at the same time is inconsistent with solvation playing the exclusive role since the lower wavelength band should have increased on cooling. An even wider temperature range was feasibleso in decalin where the range -74" to +162" could be covered.Particularly noticeable (Fig. 15) is the in- crease in the negative CD band upon raising the temperature which is best interpreted in terms of an augmented contribution by a negatively rotating non-solvated conformer such as (XIIIb) and/or (MIIC). The effect of temperature and solvent changes upon the circular dichroismso of ( +)-isomenthone (XIV) will be reported elsewhere in detail but it is pertinent to mention that the very strong positive Cotton effect first noted in ORD measurements,8l clearly eliminates63 the possibility that the conformer XIVb with an equatorial isopropyl group plays an important role. A mixture of XIVa and XIVc is most consistent63 with the observed ORD and CD results.(XIVb) (XIVC) The existence of at least three different forms is demonstrated in a graphic manner in Fig. 16 which contains the CD curves of 2-0x0-1-p-menthanol A I \ n a -3 -4 -5' I I ' ' ' ' 220 240 260 280 300320 340 (my> FIG. 16. Circular dichroism curves of 2-0x0-1-p-menthanol (XV)in decalin at +156" +25" and -74". *l Ohloff Osiecki and Djerassi Gem. Bet-. 1962 a5 1400. PROCEEDINGS (Ws2 measured in decalin solution at -74" +25" 5 a-androstan-3-one (XVI)63 increases considerably and +156". The evidence for the occurrence of at upon lowering the temperature as exemplified by least three forms is clear since the rotational strength at room temperature is more negative than at +156" while a positive CD curve is obtained at low tempera- tures.The earlief13 ORD measurements conducted at room temperature in different solvents showed a positive Cotton effect in polar media (e.g.,methanol dimethyl sulphoxide) but a negative one in non-polar solvents (iso-octane carbon tetrachloride). This was interpreted in terms of a conformational equilibrium between the chair form (XVa) (polar solvent) with an axial hydroxyl group incapable of intramolecular hydrogen bonding and the alternate boat conformation (XVb),* in which hydrogen bond- ing between the equatorial hydroxyl group and the carbonyl function is feasible. These conclusions were consistent with the predictions from the octant rule (positive Cotton effect for XVa negative for XVb) as well as the observeds3 wavelength shifts.It should be noted that the alternate twist form (XVc) (carbon atoms 1 and 4 the "points" of the twist) is excluded since it would display a strongly positive Cotton effect. If we turn now to the CD results (Fig. 16) in tlecalin we can interpret them at least qualitatively ty assuming that the conformer population is changed at -74" in the direction of (XVa) (positive Cotton effect no intramolecular hydrogen bond) while at elevated temperatures (e.g. +152") we are dealing with increased quantities of (XVb) (negative Cotton effect) in which the intramolecular hydrogen bond has been broken and/or with the appearance of the positively rotating twist form (XVc). At room temperature the hydrogen-bonded form of (XVb) enters into play.Wa) (XV b) (XVd The examples cited so far have all involved con- formational changes of cyclic ketones which were reflected in alterations in the Cotton effect (as measured by ORD or CD) because the relative posi- tions of the various atoms in the appropriate octants differed in each conformer. The same effect can be produced by free rotational isomerism which is usually much more difficult to measure and some pertinent resultsso bearing on this point will now be given. The rotational strength of 2 a-isopropyl- 19-nor- circular dichroism data reproduced in Fig. 17. Pre-3 26 'i FIG. 17. Circular dichroism curves of 2a-isopt-opyl-19-nor-5a-androstan-3-one(XVZ)in EPA at 25" and -192".cisely the same situation is encounteredM in 2a-iso- propylcholestan-3-one (XVIIT).63 On the other hand no change in rotational strength is observedso in 2p-isopropyl-19-nor-5 a-androstan-3-one (XVII)83 over the range +25" to -192". These results are interpreted as meaning that in the two equatorially substituted isopropyl ketones (XVI and XViII) one is dealing with a rotamer mixture at room tempera- ture and that upon lowering the temperature to the boiling point of liquid nitrogen free rotation is restricted and the proportion of the favoured rotamer enriched. In the axial isomer (XVII) on the other hand there probably exists already at room ternpera- ture a great preponderance of one rotamer (XVIIa) in which the isopropyl group assumes the most favoured position namely that in which the iso- propyl hydrogen atom rather than one of its methyl groups is pointed towards the angular hydrogen atom.If such a condition obtains at +25" then no change would be expected upon lowering the temperature. The rotational change illustrated in Fig. 17 was produced by leaving the geometry of the chromo- phore-containing portion of the molecule undis- turbed and simply altering the relative population of the atoms of the isopropyl group in the various * The corresponding twist form with carbon atoms 2 and 5 the "points" of the twist (seeref. 69) is probably a more likely representation. Newhall J. Org. Chem. 1959 24 1673. Djerassi Records and Bach Chem. and Ind.1961 258. OCTOBER 1964 1 (XVI I I) (XVII) (XVI la) octants. The reverse can also be accomplished namely to examine free rotation in a substance where the carbonyl group is at liberty to move rela- tive to the cyclic framework. In 5 a-pregnan-20-one (XIX)and its 17a-isomer (XX) the acetyl group is theoretically free to rotate around C-17. In actual fact free rotation is severely restricted-in the 17@-isomer(XIX) by the C-18 angular methyl group as well as the equatorial hydrogens at C-12 and (2-16 and in the 17a-isomer (XX) by the axial hydrogen atoms at C-12 C-14 and perhaps C-16. This restricted rotation manifests itself in the large ampli- tude28 of the ORD Cotton effects of such 20-keto- steroids and in the observation that the rotational strength is affected to only a small extent over the range +25" to -192" as determineda0 by CD measurements.The situation is drastically altered in 3/3-acetoxyhexanordammaran-20-one (XXI),S4which for stereochemical purposes may be considered a 20-keto-steroid (XIX) analogue lacking the C-18 angular methyl group. The ORD curves5of this ketone (XXI) is charac- terised by a weak negative Cotton effect in marked contrast to the strongly positive Cotton effect of the 20-keto-steroid (XIX). This difference has been ascribeds5 to relatively free rotation in the dammaran- 20-one derivative (XXI) since the restraint imposed by the angular methyl group is now absent. A striking confirmation of this view is afforded by the temperaturedependent CD data collected in Fig.18. 'Q -2+ \ \ ' i I 5-261 ' I Y -3oL-341-38 ' I ?I 'I ' \J I200 1250 I I350 FIG. 18. Circular dichroism curves of 3/3-acetoxy-hexanordammuran-20-one (XXI) in EPA at +25" -74" and -192". It will be noted that the rotational strength changes only slightly in the range +25" to -74" but then increases greatly upon cooling to -192". Evidently the energy difference between the various rotamers is so small that cooling to very low temperature is required before a meaningful preponderance of a preferred ro tamer is reached . In the previous discussion of "chromophoric derivatives," it was noted (see Table 1) that many of the newly introduced chromophores are situated in portions of the molecule that are subject to free rota- tion.Nevertheless in most instances a direct relation between the sign of the Cotton effect of that deriva- tive and the absolute configuration of the nearest asymmetric centre was possible. The most likely ex- planati0n~~9~~ is that the predominant rotamer com- position is altered only slightly by changes around the asymmetric centre which in general is some distance from the appropriate chromophore. Low- temperature CD studies of such substances are now under way in our laboratory to examine this question in greater detail. All the work discussed so far has dealt with inherently symmetric chromophores-the optical activity being due to vicinal action by asymmetrically situated atomic substituents.In recent years a second type of chromophore-the inherently dissymmetric Mills J. 1956 2196. For stereochemistry see Biellmann CrabbB and Ourisson Tetrahedron 1958 3 303. 85 Djerassi Mitscher and Mitscher J. Amer. Chem. SOC.,1959 81 947. PROCEEDINGS illustration is offered in Fig. 19 with the ORD curve one-has been studied in some detai1,22~49~50~60~86-88 and its bearing on some conformational problems will now be considered briefly. Inherently dissym- metric chromophores as for instance the twisted biphenyls4840 or hexaheliciness possess an inherent chirality which leads to optical activity irrespective of its molecular environment. The rotational strength of such chromophores is in general much greater than that of the asymmetrically disturbed inherently symmetric chromophores.Interesting examples are a/?-unsaturated ketones.87 When planar they resemble closely their saturated analogues in terms of representing an inherently symmetric chromo- phore. However when non-planarity enters which is usually the case in cyclic systems an inherent chirality is introduced and its sense (left-handed or right-handed) can be related to the sign of the Cotton effect quite analogous to the situation in cisoid dienes,sg whose n-system resembles that of a/?-unsaturated ketones. This relationship between chirality and sign of Cotton effect applies to both the n -n*and n-n* absorption bands. While the original ORD studies1s126of a/?-unsaturated ketones were limited to the n -+n*region recent improvements in spectro- polarimetric instrumentation have permitted pene- trations7 through the high-intensity K-band.An I I 225 300 400 500 bJr> FIG.19. Optical rotatory dispersion curve (methanol) of umbellulone (XXII). of umbellulone (XXII) measured with the Bendix- Ericsson spectropolarimeter ; the positive Cotton effect associated with the n .-f n* transition as well as the powerful negative one due to the 7~ -+ n* transition are clearly defined. The angle of skew in the non-planar a/?-unsaturated carbonyl chromo- phore determines the extent to which the substance under examination behaves like an inherently dis- symmetric chromophone. When this angle is small the chirality contribution may be partially or com- pletely offset by vicinal interaction of the type ob- served in asymmetrically perturbed intrinsically symmetric chromophores.Furthermore the handed- ness of the C =C =C =O chromophore is inverted in changing the conformation of a cyclohexanone ring and it is conceivable that the rotatory contribution of one conformer though present in much smaller amount may dominate the overall sign of the Cotton effect. Consequently care must be exercised in inter- preting the sign of the Cotton effect in terms of a given conformation. However if a reference ORD or CD curve is available departure in sign from it may be considered prima facie evidence for con- formational distortion. Originally,26 such Cotton effect anomalies were studied in C-6 substituted d4-3-keto-steroids and associated with distortions in ring B.The more recent interpreted in the light of the inherently dissymmetric chromophore concept for the ap-unsaturated carbonyl moiety show that distortion of ring A is involved. Thus 1 a-methyl- 19-norprogesterone (XXIII) ex-hibits a Cotton effect similar to that of the lower homologue 19-norprogesterone (XXIV) while an inversion in sign is ob~erved~~,~~ in the lp-methyl isomer (XXV) presumably due to interaction between the equatorial lp-methyl group and the 11 whydrogen atom [see also earlier discussion of (VII) versus (VIII)]. Similar instances of conforma- tional distortion in d4-3-keto-steroids uncovered through ORD measurements on 213-90and 6p-91 substituted analogues have been reported recently.(XXIII)’; R=Me (XXIV) ;R=H 86 Mislow Glass Moscowitz and Djerassi J. Amer. Chem. SOC. 1961 83 2771. 87 Djerassi Records Bunnenberg Mislow and Moscowitz J. Amer. Chem. SOC. 1962 84 870. 88 For further discussion see Moscowitz Tetrahedron 1961,13,48; Mislow Ann. New York Acad. Sci. 1962,93,457; Cookson and Hudec J. 1962 429; Whalley Chem. and Znd. 1962 1024. 89 Moscowitz Charney Weiss and Ziffer J. Amer. Chem. SOC. 1961 83 4461. 90 Kuriyama Kondo and Tori Tetrahedron Letters 1963 1485. 9l Davies and Petrow Tetrahedron 1963 19 1771. For n.m.r. studies of similar ketones see Collins Hobbs and Sternhell Austral. J. Chem. 1963 16 1030. OCTOBER 1964 This sensitivity of &unsaturated ketones towards very subtle interactions indicates that the Cotton effect of such substances should be employed with very great caution for absolute configurational deductions.24r 16-0 x 2 8-c 0 c 2 I 0-4 I I I I 225 300 400 500 600 A(Y) FIG.20. Optical rotatory dispersion curve (dioxan) of d3-trans-10-methyloctal-Zone (XXIX)and AlO-trans-1,3-methylbicyclo(5,4,0)undecen-9-one(XXX). '4--6t -1 2t-I 4bo I 225 -300 500 660 (mp) FIG.21. Optical rotatory dispersion curves (dioxan) of A3(9)-8-methylhydrinden-2-one(XXXI) and A7-lg- methylbicyclo(5,3,0)decen-Pone(XXXII). A striking illustration is afforded by the observa-tiong2 that the saturated bicyclic ketones (XXVI) (XXVII) and (XXVIII) all exhibit positive Cotton effects irrespective of the nature of the adjacent non-ketonic ring while inversions in sign are en- countered in the ab-unsaturated ketone pairs (XXIX) versus (XXX) (Fig.20) and (XXXI) versus (XXXII) (Fig. 21). This inversion in the Cotton effect in the unsaturated ketones is only attributable to a conformational change imparted by the change in size of the adjacent ring since the substances belong to the same absolute configurational series. These results have an obvious bearing on the utilisa- tion of ORD and CD for absolute configurational assignments among perhydroazulenic terpene~.~~ (XXVI = 3-6) (XXVI I) From the above discussion it should be clear that while there is much overlap between optical rotatory dispersion and circular dichroism as far as organic chemical applications are concerned the two methods do complement each other in several areas in a very desirable fashion.Studies in stereochem- istry notably in conformational analysis have benefited greatly from the availability of these tools and much progress can still be anticipated. This is particularly true if improved instrumentation can keep pace with the demands and interests of the chemist. In earlier review^^^^^^ I have emphasised the need for better spectropolarimeters with farther ultra- violet penetration as well as for a convenient instru- ment to measure circular dichroism. The recent im- provements in spectr~polarimetry~~ have to a large extent satisfied this demand; at present penetration below 190 mp is feasible and many chromophores hitherto outside the range of standard spectro- polarimetry now yield interesting Cotton effect 92 Djerassi and Gurst J.Amer. Chem. Soc. 1964 86 1755. 93 See Djerassi Osiecki and Herz J. Org. Chem. 1957 22 1361. g4 Djerassi Rec. Chem. Progress 1959 20 141. 95 Djerassi Tetrahedron 1961 13 28. 96 For a practical performance comparison of the four commercially available spectropolarimeters see ref. 54. curves which are amenable to theoretical inter- pretation and hence practical utilisation. The instru- mentation situation is less bright in the circular dichroism field simply because the present com- mercially available instrument does not reach as far into the ultravioletg7 as several of the spectropolari- meters.This is a serious drawbackg8 and since few laboratories will purchase both instruments because of the expense factor the choice will generally be in favour of ORD owing to the present greater spectral penetration of spectropolarimeters. What is really needed is to be able to measure both optical rotatory dispersion and circular dichroism down to 185 mp with one single instrument. There is no practical reason why such a combined instru- ment cannot be constructed. When this is accom- plished the organic chemist as well as the theoretician interested in optical phenomena will have at their disposal the instrument of choice. In view of the past O7 For a typical example see Fig. 7 in ref. 33.PROCEEDINGS level of excellence in the design of spectropolari- meters I trust that this challenge to British ingenuity in instrumentation will not remain unheeded. As can be seen from the many references I owe to my students and other collaborators a debt the extent of which cannot be expressed adequately in such an acknowledgment. Suffice it to say that virtually none of the work presented here could have been accomplished without their most able assistance. I am especially indebted to Dr. E. Bunnenberg for many instrumental contributions to Mrs. Ruth Records for practically operating during the past four years two instruments simultaneously and to Professor A. Moscowitz of the University of Min-nesota for numerous stimulating discussions on theoretical points.Financial support was provided by the National Institutes of Health of the U.S. Public Health Service and by the National Science Foundation. s8 A description of a research instrument with greater ultraviolet penetration has been published recently by M. Grosjean and M. Tari Compt. rend. 1964 258 2034. COMMUNICATIONS ‘The Formation of Cyclopenta [c]quinolizines from 3-1’-Dimethylaminovinylindolizinesand Dimethyl Acetylenedicarboxylate By W. K. GIBSON and D. LEAVER* WE investigated the reaction bet ween dimethyl nium2 and the benzo [c]quinolizinium3 ion. Further acetylenedicarboxylate and the enamines (I; R=Me evidence for the presence of a quinolizine nucleus Ph or C0,Me) with a view to synthesising deriva- tives of the hypotheticall cyc1[4,3,2]azine (11).It is now clear however that the reaction which when carried out in boiling toluene is accompanied by loss of dimethylamine leads to the cyclopenta [clquino- lizines (IlIa). The first indication that the products were not based on the ring system (11) was afforded by the presence of a low field absorption (between T -0.4 and 0.3) in their n.m.r. spectra which was attributable to the a-pyridine proton (position 9 in 111) since its multiplicity varied in a predictable manner with the position of methyl substitution in the pyridine ring. Hydrolysis and decarboxylation of the orange diester (IIIa; R=Me) was effected by boiling hydrochloric acid and the product (IIIb; R=Me) showed an ultraviolet spectrum in acid solution which was attributable to the ion (IV or its 3H- isomer) since it resembled closely but was interposed in wavelength between the spectra of the quinolizi- * Department of Chemistry University of Edinburgh.1 Windgassen Saunders and Boekelheide J. Arner. Chem. SOC.,1959 81 1459. a Boekelheide and Gall J. Arner. Chern. SOC.,1954 76,1832. Glover and Jones J. 1958 3021. OCTOBER 1964 was afforded by oxidation of the triester (IIIa; R=CO,Me) with nitric acid to the known4 betaine (V) which was identified by comparison with an authentic specimen. Rings A and B of the cyclopenta[c]quinolizine nucleus are iso-welectronic with azulene and in accord with this structure compounds (IIIb) readily undergo electrophilic substitution to give mono- and di-acyl monoarylazo and mononitroso derivatives.Halogenation and nitration fail because of decomposition. The formation of the 1 ,Zdiesters (IIIa) proceeded by way of the intermediate compounds (VI) which can be isolated by carrying out the reaction in a cold aprotic solvent and which are converted into the cyclopenta [c]quinolizines by boiling toluene. Compounds (VI) are clearly formed by collapse of the zwitterion (Vll),in the way established5 for related reactions to give a cyclobutene which isomerises to the butadiene (VI). By carrying out the initial addi- 33 1 tion reaction in methanol however the zwitterion can be intercepted by proton transfer to give the isomeric butadiene (WII) which can be converted into the 2,3-diester (IIJc) by boiling xylene.The isomeric 1,2- and 2,3-diesters (IIIa and IIIc; R=Ph) were converted into the same monocarboxylic acid (IIId; R=Ph) by partial hydrolysis and decarboxyla- tion. The very low r value of the 9-proton in the 1,2- diesters (IIIa) is evidently partly due to a direct de- shielding effect of the 1-methoxycarbonyl group since the decarboxylated compounds (1ICIb) and the 2,3-diesters (IIIc) show T values (1.2-1.6) more normal for cc-pyridine protons. The 9-protons in the mono- and di-benzoyl compounds also show very low T values (-0.8 and -0-2 respectively) and this is taken as evidence that acylation occurs first in the 1-position. The second acyl group is considered to enter the 3-position.(Received August 21st 1964.) Bradsher and Barker J. Org. Chem. 1964 29 452. Berchtold and Uhlig J. Org. Chem. 1963,28,1459; Brannock Burpitt and Thweatt ibid. p. 1462. The Reaction of Tosyl Derivatives of Inositols with Sodium Benzoate in Dimethylformamide By S. J. ANGYAL and T. S. STEWART* THEreaction of sulphonyl derivatives of sugars and polyols with sodium benzoate in boiling dimethyl- formamide has recently acquired importance.lP2 If the sulphonyl group is in a furanose or pyranose ring the reported outcome2 of the reaction is either dis- placement of the sulphonyloxy-group by a benzoate group with inversion or recovery of unchanged starting material. Cyclitols being good model com- pounds for the behaviour of carbohydrates we have studied this reaction with a number of tosylated inositols.An unexpectedly great variety of reactions was observed. In only one instance did benzoate exchange with inversion occur and only one of the compounds was recovered unchanged; all the other compounds reacted however and it was soon realised that their reactions took place even in the absence of sodium benzoate. Three reactions were observed to occur in the presence or absence of sodium benzoate depending on the nature of the groups attached to the vicinal carbon atoms (i) If there is a neighbouring acetoxyl group in a trans-position [e.g. 1,2,3,4-tetra-0-acetyl-5-0-methyl-6-0-tosyl-( -)-inositol J and the solvent contains some water inversion takes place through the initial formation of a cyclic acetoxonium ion.Similar reactions of acyclic polyols have recently been rep~rted.~ (ii) If the neighbouring group is hydroxyl in a trans-position [e.g. 2-0-methyl-1 -0-tosyl-(-)-inositol] an epoxide and the two products resulting from its subsequent opening are formed. (iii) If there is a vicinal and cis-tosyloxy- group [3,4-di-O-benzyl-1,2-0-cyclohexylidene-5,6-di-0-tosyl-( -)-inositol] elimination occurs with the formation of an enol tosylate. A similar instance has recently been described* involving a derivative of an acyclic polyol. In the compound [1 2:5,6-di-O-isopropylidene-3-0-methyl-4-0-tosyl-(+)-inosi to1 3 that displayed ben- zoate exchange with inversion and in the compound [1,2:5,6-di- 0-isopropylidene- 3,4-di- 0-tosyl-(-)- inositol] that did not react there are no neighbouring hydrogen atoms acetoxyl or hydroxyl groups in trans-relationship to the tosyl groups.(Received,Jury 22124 1964.) * School of Chemistry The University of New South Wales Kensington N.S.W. Reist Goodman and Baker J. Amer. Chem. Soc. 1958 80 5775; Bukhari Foster Lehmann and Webber J., 1963 2287; Bukhari Foster Lehmann Webber and Westwood J. 1963 2291 ;Baggett Bukhari. Foster Lehmann and Webber J. 1963,4157. Reist Spencer pd Baker J. Org. Chem. 1959 24 231 ;Foster Harrison Lehmann and Webber J. 1963 4471 ; Hill Hough and kchardson Proc. Chem. SOC.,1963,346. Bukhari Foster Randall and Webber J. 1963,4167; Baker and Haines J. Org. Chem. 1963,28,438. Bukhari Foster and Webber J.1964 2514. PROCEEDINGS The Photochemistry of Phenalen-1-one By H. KOLLER,G. P. RABOLD, K. WEIS* and T. K. MUKHERJEE~ IRRADIATION of aromatic ketones generally gives rnin.-l at 25"). Strong electron spin resonance bimolecular reduction products whereas ap-un- (e.s.r.) signals are associated with the coloured solu- saturated ketones dimerise to cyclobutanes.2 Di- tions :a 24-line spectrum of six quartets (neutral) and merisation is still the preferred reaction if the double a six-line spectrum (basic). We assign these spectra to bond is conjugated with an aromatic ring. The com- the 1-hydroxyphenalen-1 -yl radical (11) and its bination of these structural features in phenalen-l- anion re~pectively,~ which have been previously one (I) leads to unique behaviour.detected by p~larography.~ However the optical Although irradiation of ketone (I) in outgassed spectra shown in the Figure are not due to these benzene methylcyclohexane or carbon tetrachloride radicals. This conclusion is based on (1) a faster (100-w mercury lamp 20-75 hr.) results in only e.s.r. signal decay (k = 0.18 min.-l)s than optical slight change the solution in propan-2-01 becomes decay (2) the absence of transient colour in diphenyl- deep green after a few minutes (see Figure). Identical methane solutions which show the 24-line e.s.r. spectrum and (3) the approximate quality of the rate of colour formation observed by flash technique and the rate of radical decay. In propan-2-01 and methanol irradiation produces at least six compounds.2,3-Dihydrophenalen-l -one (111) was isolated in both solvents in 13% yield [based on converted ketone (I)]. In diphenyl-absorption bands are produced in methanol ethanol methane the ketone (111) is the major product. This ethyl acetate and acetone. In propan-2-01 the colour direct photochemical reduction of a double bond shows first-order decay in the dark (k = 4.1 x appears to be without precedent although a sensi- min.-l at 25"); in the other solvents the decay is tised reduction has been rep~rted.~ The propanol more complex. Oxygen or iodine immediately dis- reaction also furnished two yellow compounds charges the colour. In basic solution a deep orange- which have analytical and spectral data consistent red colour is produced (see Figure) which is also with their being diketonic dimers of ketone (I).No oxygen-sensitive and decays more slowly (k = 3.2 x acetone was detected and an attempt to trap Wavelength (my) Spectra of intermediates from 1 x 10-3~-phenalen-1-one in (l)propan-2-01 and (2) O-lM-NaOH(2.3:1 propan- 2-ol-water (A)before (B)immediately after irradiation (C) after admission of oxygen. * Department of Chemistry Northeastern University Boston 15 Mass. U.S.A. t Energetics Branch Air Force Cambridge Research Laboratories Bedford Mass. U.S.A. G. Porter and P. Suppan Proc. Chem. SOC.,1964 191 ;J. N. Pitts Jr. H. W. Johnson Jr. and T. Kuwana J. Phys. Chem. 1962 66 2456 and references cited therein. 2 P. E. Eaton J. Amer. Chem. SOC.,1962 84 2344; A. Mustafa Chem.Rev. 1952 51 1. 3 G. P. Rabold and K. Weiss manuscript in preparation. H. Berg Preprints Fifth Internat. Symp. on Free Radicals Uppsala 1961 paper 8; H. Beckmann Austral. J. Chem. 1961,14,229; H. Beckmann and P. Silberman Chem. and Znd. 1955 1635. 6 G. W. Griffin and E. J. O'ConnelI J. Amer. Chem. SOC.,1962,84,4148. OCTOBER 1964 HO-CMe,. radicals as terebinic acid by the addition of maleic acid6 failed. The transient colours are reminiscent of the inter- mediate in the photo-reduction of benzophenone in propan-2-01 for which radical structures could not be confirmed by e.s.r. measurement^.^ Our results leave little doubt that the radicals generated by re- action of excited ketone with solvent are precursors of the coloured diamagnetic intermediates.The latter appear to incorporate the solvent or a solvent-derived oxidation product. Significantly solvents in which colour is observed either bear carbonyl groups or can give rise to them by oxidation. Although the sensi- tivity to oxygen and iodine may be an intrinsic pro- perty of the intermediate it is more likely to be due to an equilibrium with radicals in which the dia- magnetic molecule is heavily favoured. (Received August 5th 1964.) Cf. G. 0.Schenck G. Koltzenburg and H. Grossmann Angew. Chem. 1957 69 177. 7 G. 0. Schenck W. Meder and M. Pape Proc. Internat. Conf. Peaceful Uses At. Energy Geneva 1958 29 352; J. H. Sharp T. Kuwana A. Osborne and J. N. Pitts Jr. Chem. and Znd. 1962 508; J. N. Pitts Jr. R. L. Letsinger, R.P. Taylor J. M. Patterson G. Recktenwald and R. B. Martin J. Amer. Chem. Soc. 1959 81 1068. Direct Substitution of I-by Ci-in Cr(H,O),Pf By MICHAEL ARDON* IT has been generally assumedl that substitution reactions of octahedral complexes in which ligand X-is substituted by ligand Y-as in MA,Xn+ + Y-+ MA,Yn+ + X-(1) proceed via an intermediate aquo (or hydroxo) complex MA,Xn+ + H20 -MA,H,O@+')+ + X-(2) MA5H 2O@+l)++ Y-3 MA5Yn++ H20 (3) This generalization? is brought into serious question by the finding reported here that even in mono- substituted aquo-complexes such as Cr(H20),12+ direct substitution takes place without the inter- mediate formation of Cr(H20)2+ Cr(H20),12++ Cl-Cr(H,0),C12+ + I-(4) -t The iodopenta-aquochromic ion3 is kinetically (as well as thermodynamically) much less stable to aquation than other halogenopenta-aquochromic ions and is aquated completely within a few hours in aqueous perchloric acid at room temperature.When other ions are absent the sole product is Cr(H20)2+ but if C1- is present a considerable quantity of Cr(H20),C12+ is produced together with Cr(H20),3+. Cr(H20),12+ was prepared by oxidation of chromous perchlorate with iodine and purified by absorption on a cooled cation-exchange column (Dowex 50 4x) and elution with 0-4~-perchloric acid. This operation was carried out at 0.5". The rate of decomposition of Cr12+ was measured spectrophotometrically (at 650 mp) at 30" in IM- perchloric and 1 M-hydrochloric acid respectively.The pseudo-first-order rate constant was determined from the plot of log (Dt -Dco)versus t (found 0 0138 min.-l and 0.0147 min.-l in 1~-HC10 and 1 M-HCl respectively). The solutions were kept at 30" for 7 hr. (-J 8 half lives) and were then absorbed on cation-exchange columns (Dowex 50 8 x). The perchloric acid solu- tion contained only the Cr(H20),3+ ion. In the hydrochloric acid solution a green band was ob- served below the blue hexaquo band and after elution with 1M-perchloric acid it was identified as Cr(H2O),CI2$-. The ratio of CrC12+ to Cr(H20),3+ was 14-3:lOO in this solution and is considerably higher than the relative increase in decomposition rate observed in 1 M-hydrochloric acid (6.5 :100). The chloro-complex could not be formed via the Cr(H20)63+ion by a secondary reaction with C1- as in kl Cr(H20)t++ C1-+Cr(H2O),Cl2+ + H20 (5) k2 because this reaction is too slow at 30" the rate constant k is smaller than 1.6 x moles 1-1 set.so that less than 0.5 % of the complex could be formed by this reaction path. In order to check whether the reaction products of the aquation re- action of Cr12+ do not catalyse the formation of CrCP+ by reaction (5) a control experiment was con- ducted in which the iodo-complex was aquated completely in dilute perchloric acid and was then added to a lM-hydrochloric acid solution. This mixture was kept for 7 hr. at 30"c and analysed by ion-exchange chromatography-no trace of CrC12+ could be detected. (Received July 6th 1964.) * Department of Inorganic and Analytical Chemistry The Hebrew University of Jerusalem Israel.iThe only reported exception concerns the azidopentacyanocobaltic anion in which direct substitution of azide by thiocyanate takes place.2 Stranks "Modern Coordination Chemistry" Ed. Lewis and Wilkins Interscience 1960 p. 136. Haim and Wilmarth J. Inurg. Chem. 1962 1,583. Taube and Myers J. Amer. Chem. Suc. 1954 76 2103. 4 Baltisberger and King J. Amer. Chem. SOC.,1964 86 795. PROCEEDINGS ~~ Conformational Free-energy Differences in 3p-Substituted Steroids By D. NEVILLE JONES and D. E. KIME* THEdifferences in free energy between a substituent axially and equatorially orientated in a cyclohexane ring ('conformational free-energy differences') have been adduced from investigations of monocyclic compounds.l These conformational free-energy differences are not always additive when applied to disubstituted monocyclic cyclohexane deriva- tives.112 Starting Method K -AGO material (kcal.) I;R=H t 2-95 11; R = H t 2.57 I;R=H C 4.95 I;R=OH t 4.83 1.57 11; R = OH t 4-65 1 -54 I;R=OH C 15.8 1 *93 1; R = OAC t 6-12 1-80 11; R = OAC t 5.55 1-72 I; R = C1 t 4.04 1-40 11; R = C1 t 3-97 1-37 I; R = C1 C 7-26 1-39 I; R = OMe t 4.40 1*48 * to the nearest 0.1 kcal.t this value taken in further calculations. t thermal equilibration at 230". c acid-catalysed equilibration in aqueous ethanol at 80". We have measured the free-energy differences between substituents axially and equatorially orien- tated at C-3 in steroids and found them to be in general agreement with values obtained in mono- cyclic compounds.Our method involved the equilibration of 38-substituted 5a-cholestan-6-ones with 3p-substituted 5/3-cholestan-6-ones by heating them to 230" under nitrogen in a glass vessel for 3-5 hr. In each case equilibrium was approached from both sides. The equilibrium constant KH was first determined for the interconversion of 5a-cholestan-6-one (I; R = H) and 58-cholestan-6-one (11 ;R = H) and then K was determined for various 3p-substituted derivatives of 5a-and 5/3-cholestan-6- one. Conformational analysis indicated that the introduction of a 3p-substituent X in these com- pounds should lead to values of K lower than KH since such substituents are equatorial in (I; R = X) and axial in (11; R = X).-AGO -(dGo,-dGo,)* Lit. Ref. (kcal.) (kcal.) values 1-08t 0.9 3 0.95 1-2 4 1.12 1 0-7 04-0-7 1 0.6 0.3 0.3 0.3-4.5 1 0.4 0.54.7 1 0.3 Equilibrium constants were determined by direct isolation of each component by thin-layer chromato- graphy. Then AGO was calculated for the equili- brium (I; R = H) + (II; R = H) and also AGO for the equilibrium (I; R = X) $ (11; R = x). The conformational free-energy differences between C-3 axial and equatorial substituents was then given by AGO -AGO (see Table). The conformational free-energy values recorded in the Table are reliable only to f0.1 kcal.at best as in other methods of determination of free-energy values,l and our values are in general agreement with those obtained previously. The disparity in the values obtained for the hydroxyl group in the absence of solvent (thermal equilibration) and in the presence of ethanol (acid-catalysed equilibration) can be * Chemistry Department Sheffield University. Eliel J. Chem. Educ. 1960,87 1 26; "Stereochemistry of Carbon Compounds" McGraw-Hill New York 1962 p. 234. a Eliel and Lukach J. Amer. Chem. Soc. 1957 79 5986. Turner J. Amer. Chem. Suc. 1952 74 2118. * Allinger Darooge and Hermann J. Org. Chem. 1961 26 3626. OCTOBER 1964 335 attributed to the greater effective size of the hydroxy- ences determined in monocyclic systems are applic- group in the latter due to intermolecular hydrogen able to 3p-substituted steroids.Conversely con- b0nding.l The values obtained for the acetate group formational free-energy values can conveniently be agree with that of Eliel and Gianni5 (0.7) but not with determined by using the 3p-substituted cholestan-6- that of Chapman and his co-workers6 (1.5). one system. The method is capable of considerable me agreement betwen the conformational free- refinement since optical rotatory dispersion tech- energy differences obtained after thermal equilibra- niques can be used to determine the equilibrium tion at 2300 and acid-catalysed equilibration at Constants aCCUrdtely.4*7 Previous equilibration 80° and the previously reported values obtained at methods except that of Elid and Rerick required various temperatures between 25” and go0 indicate that the group being investigated was itself epi- that the entropy changes involved in these equilibra- merizabk and the kinetic techniques were aPPlic- tions are very small.able only to reactive groups. These requirements It appears that conformational free-energy differ- do not to the present procedure. (Received August 20th 1964.) Eliel and Gianni Tetrahedron Letters 1962 97. IJ Chapman Parker and Smith J. 1960 3634. ’Djerassi Riniker and Riniker J. Amer. Chem. SOC.,1956 78 6362. 13 Eliel and Rerick J. Arner. Chem. SOC.,1960 82 1367. The Quenching of Mercury 2537A Resonance Radiation by Fluorinated Ole6ns By A. R. TROBRIDGE and K. R. JENNINGS* the quenching of mercury 2537A combustion in a copper oxide furnace and by mass ALTHOUGH against [olefin]/[N,O] resonance radiation by hydrocarbons has received spectrometry.A plot of 1/@~ considerable attention,l- there are very few values was made in each case and the method of least available in the literature of the quenching cross- squares was used to evaluate the quenching cross- sections of fluorinated compounds.* Gunning and section of the olefin relative to that of nitrous oxide.Strausz2 have suggested that the Hg 63P atom is The figures in the Table are based on a value of electrophilic in nature and it is therefore to be oz = 18.0812for nitrous 0xide.l expected that if fluorine replaces hydrogen in a The progressive reduction of the quenching cross- moIecule the quenching cross-section will decrease sections in the series CzH4 -CzF4 confirms the as a result of the strong inductive effect exerted by electrophilic nature of the Hg 63P atom.The two fluorine. values quoted for the propenes show a similar trend As part of a study of the reactions of fluorinated and may be compared with a2 = 42.6A2 for olefins in mercury-photosensitised systems we have CH,-CH=CH,. The similarity in the quenching measured the quenching cross-sections of a number cross-sections of C2F4 and C,F suggests that the of olefins and these together with relevant literature CF group and the F atom deactivate the double values are given in the Table. bond by about the same amount. Further work is in 02 (A2) 31 29.8 27.2 19.7 10.6 10.9 36.6 this work o2(AZ) 311 26.34 9.34 literature These values were obtained in a circulating system progress with the aim of determining the effect on at 23 flot the nitrous oxide technique developed the quenching cross-section of varying the position by Cvetanovic being used.5 Non-condensible gases and degree of substitution in other fluorinated were collected by a Toepler pump and analysed by olefins.(Received September 16th 1964.) * Department of Chemistrv. The University. Sheffield. 10. R. J. Cvetanovic “Progr&s in Reaction Kinetics,” Vol. 11 Pergamon Ed. G. Porter 1964. H. E. Gunning and 0.P. Strausz “Advances in Photochemistry,” Vol. I Wiley Ed. W. A. Noyes. G. S. Hammond, and J. N. Pitts 1963. Y. Rousseau and H. E.Gunning Canad. J. Chem. 1963,41,465. M. G. Bellas Y. Rousseau 0.P. Strausz and H. E. Gunning J. Chem. Phys. 1964 41 768. ‘R. J. Cvetanovic,J. Chem. Phys. 1955 23 1208. PROCEEDINGS ~~~~~ ~ ~ ~~ Palladium-Charcoal Induced Isomerization of Diterpenoid Resin Acids* By C. T. MATHEW,Miss G. SENGUPTA,and P. C. DUTTA~ IN an earlier communication,l the stereochemistry of a bicyclic keto-acid m.p. 141 O was depicted as (I) because of its conversion into methyl dehydro- deisopropylabietate (11). Spencer,2 reported the synthesis of an isomeric keto-acid m.p. 184" which he also converted into (11). It therefore became neces- sary to re-examine our previous results and we are now able to report that our bicyclic acid is in fact (111) and that Spencer's acid is (I) as reported.2 Discernibly the discrepancy arose during the dehy- drogenation step involving heating with palladium- charcoa11,2 leading to isomerization at the ring junction.Conversion of our acid into a known tricarbocyclic compound (e.g. VII) through pro- cesses not involving possibility of isomerization was envisaged as a solution to this problem. The ester (1V)l was converted into the enol acetate (Amax. 268 mp log E 3-8 in alcohol) by treatment with acetic anhydride acetyl chloride and ~yridine.~ Bromina-tion with N-bromosuccinimide in carbon tetrachlor- ide in the presence of fused potassium carbonate4 followed by dehydrobromination with collidine pro- duced (V) which on mild alkaline hydrolysis afforded the phenol (VI).The phenolic hydroxyl group was removed by diethyl phosphite followed by lithium and amm~nia.~ On concentration the product furnished (VII) m.p. 89-90" [overall yield ca. 20% based on (IV)] the identity being established through mixed melting point with authentic material.s Our findings are thus more in confirmation of Johnson's generalizations' of axial attack in angular methylation than otherwise as suggested ear1ier.l That heating with palladium-charcoal had brought about isomerization of the cis-ester (VII) to (U) alteration having occurred at the ring junction next to the carboxyl group was further verified. The cis-ester (VIII)8 with palladium-charcoal (10%) at 235-240" for 1 hr. gave methyl trans-deoxypodocarpate (X) in about 60 % yield.Similarly (Iwgunderwent conversion into the trans-form (Xl). This type of isomerization differs from that brought about with aluminium chloride by Wenkert,l* and Ohta and Ohmori,ll in that the change occurs at the junction farther from the ben- zene ring and the former evidently proceeds through ionic mechanism. Dreiding's12 observations with a-decalones in presence of palladium-charcoal obviously involve participation of radicals. Any direct participation of the benzene ring in effecting the change at the ring junction is a remote possibility as this has also been observed with a few 9-methyl- cis-decalins.13 (V) R-COMe (VII) (VI) R=H (VIII); R=H (X) ;R = H (1x1 ;R-Pt' (XI) ;R = Pr' (Received,JuZy 31st 1964.) * These results were presented (by P.C.D.) at the International Conference on the Chemistry of Natural Products Kyoto Japan 1964.t Department of Organic Chemistry Indian Association for the Cultivation of Science Calcutta-32 India. Mathew and Dutta Proc. Chem. SOC.,1963 135. * Spencer Weaver Schwartz Greco and Smith Chem. and Ind. 1964 577; We thank Prof. Spencer for sending a copy of the manuscript of his communication before publication. Velluz Goffinet Warnant and Amiard Bull. SOC.chim. France 1957 1289. Corbett and Speden J. Chem. SOC.,1958 3710. Kenner and Williams J. Chem. SOC.,1955 522. Saha Ganguly and Dutta J. Amer. Chem. SOC.,1959 81 3670. Johnson Allen Hindersinn and Pappo J. Amer. Chem. SOC.,1962 84 2181. Ghatak Datta and Ray J.Amer. Chem. SOC.,1960 82 1728. Sharma Ghatak and Dutta Tetrahedron 1963 19 985. loWenkert and Jackson J. Amer. Chem. Sac. 1958 80 211. l1 Ohta and Ohmori Pharm. Bull. Japan 1957 5 91. l2 Ross Smith and Dreiding J. Org. Chem. 1955 20 905. lS G. Sew Gupta D. Phil. Thesis Calcutta Univ. 1964. OCTOBER 1964 337 On the Mechanism of the Solid-state cis-trans-Photoisomerisation of 1,2-Dibenzoylethylene By G. W. GRIFFIN and J. M. KELLIHER* E. J. O’CONNELL THErecent detailed studies of sensitisedl and un- sensitised2 cis-trans-photoisomerisation reactions have been restricted to the liquid phase and no completely satisfying mechanistic description of this comparatively simple photochemical process appears yet to have been ad~anced.~ Although the intimate details of the reaction remain to be clarified it is generally conceded that isomerisation in solution proceeds through rotation in either an excited state or a vibrationally excited ground state.Our work on the solid-state photochemistry of dimethyl fumarate and fumaronitrile4 and earlier preliminary reports by G. M. J. Schmidt and his co- workers on the dimerisation of the 01 and crystal modifications of cinnamic acid5 (which have since been extended to include other olefins)6 suggest that stereochemical integrity is maintained during photo- dimerisations. The results to date confirm that the stereochemistry of the dimeric cyclobutanoid pro- duct is dictated by the crystal lattice geometry of the monomer i.e.direct bond formation occurs between nearest neighbour molecules in the lattice and ex- tensive isomerisation of the olefinic substrate and/or rotational equilibration during dimerisation is precluded. It is noteworthy that trans-1 ,2-dibenzoylethylene (Ia) undergoes an exceedingly slow isomerisation to the colourless cis-modification (IIIa) on prolonged irradiation of the solid. In view of our earlier ex- perience this transformation appeared unusual al- though it is not without analogy.’ An inviting mechanism which avoids the necessity of invoking rotation in the solid consists of initial photodimerisa- tion of (Ia) to cis,trans,cis-l,2,3,4-tetrabenzoylcyclo-butane (IIa) which on subsequent irradiation under- goes cleavage in the opposite sense (11; dotted line) to afford the cis-modification (IIIa).? (Ill)a X=H b; X=D The validity of the suggested mechanism was investigated by irradiating an equimolar mixture of (Ia) and trans-1,2-di(pentadeuterobenzoyl)ethylene (Ib) which had been co-crystallised from methanol.The assumption that random distribution of (Ia) and (Ib) is attained appears eminently reasonable. The deuterated dibenzoylethylene was prepared by Friedel-Crafts acylation of deuterobenzene with fumaryl chloride and aluminium chloride in carbon disulphide. The mass spectrum of a sample of the co- crystallised mixture showed parent peaks of approxi- mately equal intensity for the protio- and deutero- components (m/e 236 and 246 Ia and Ib respeo tively).After irradiation the mixture was extracted with cyclohexane to remove preferentially the more soluble trans-form. The crude residual cis-isomer then was purified by elution chromatography on alumina followed by repeated recrystallisation. The mass spectrum of the purified cis-isomer also ex- hibited peaks at m/e 236 and 246. However the peak at m/e 241 expected for (IIIb) was conspicuously absent. This result unequivocally excludes the * (E.J.O’C. and J.M.K.) Department of Chemistry Yale University New Haven Conn. ;(G.W.G.) Tulane University New Orleans La. t The solid state isomerisations were conducted at 20”in sealed Pyrex ampoules. The olefin was deposited from solution on the inner surface of the ampoule by evaporation of solvent.A 250w photoflood lamp was employed as a light source and the irradiations were continued for a period of a week. We had established earlier that (Ia) and (IIIa) unlike typical a#?-unsaturated carbonyl compounds do not dimerise efficiently even in ~olution.~~~ After prolonged irradiation of (Ia) in benzene with a 250w-cosmetic sun lamp only trace quantities of trans,trans,trans-l,2,3,4-tetrabenzoylcyclobutane(< 1%) could be isolated. The photochemical cleavage of cyclobutane derivatives is well documented’ and in fact the “all-trans”-isomer of (Ira) was shown to be photochemically unstable in solution. (SeeGrifEn and Hager Rev. Chim. (Acad.R.P.R.) 1962 7 901.) Saltiel and Hammond J. Amer. Chem. SOC.,1963 85 2515. Schulte-Frohlinde,Annalen 1958 615 114; Orlando jun.Zimmerman and Gianni Abstracts 147th National Meeting of the American Chemical Society Philadelphia Pennsylvania April 1964 p. 20~. Hammond and Turro Science 1963 142 1541. Griffin Basinski and Vellturo Tetrahedron Letters 1960 No. 3 13; Griffin Vellturo and Furukawa J. Amer. Chem. SOC.,1961,83,2725; Griffin Basinski and Peterson J.Amer. Chem. SOC.,1962,84,1012. Schmidt Acta Cryst. 1957 10 793; Cohen and Schmidt “Reactivity of Solids,” de Boer Ed. Elsevier Publishing Co. Amsterdam 1951 p. 556; Bernstein and Quimby J. Amer. Chem. Soc. 1943 65 1845. Sadeh and Schmidt J. Amer. Chem. SOC.,1962 84 3970. Mustafa Chem. Rev. 1952 51 5. “crossover” mechanism envisioned for the trans-cis-isomerisation of solid 1,2-dibenzoylethylene and is in accord with the observations made on benzylidene- acetone in solution.One interpretation consistent with these results is that the solid-state dimerisations proceed via an excited species whose multiplicity differs from that involved .in trans-cis-isomerisations. It is possible that dimerisation (which is essentially intramolecular in character in the solid matrix) could occur within PROCEEDINGS the short lifetimes associated with the singlet state. In contrast the inefficient rotational isomerisation in the solid may require lifetimes of the order expected for triplet species. It is noteworthy that no phos- phorescence could be detected for (la) in methyl- cyclohexane-isopentane glass (5 :1) at 77”~~ This in conjunction with other evidence suggests that intersystem crossing to the triplet state is not efficient.(Received June 22nd 1964.) $ A similar mechanism has been advanced to explain the truns-cis-isomerisation of benzylideneacetone in solution (seeHouse J. Org. Chem. 1959,24 1374) and was rejected on the basis of convincing experimental data. However in view of the rigidity inherent in the crystal lattice the possibility that such a mechanism could be operative in the solid appeared reasonable. An X-ray crystallographic study has been initiated to establish if in fact trans-1,Zdibenzoylethylene does possess a lattice structure consistent with the suggested mechanism. Mass spectral data were obtained on a modified C.E.C. 21-103A instrument. Griffin and WConnell J.Amer. Chem. SOC.,1962 84 4148. The Anomalous Decomposition of o-t-Butyl-N-nitrosoacetanilide:Evidence for the Participation of an Aryne By J. 1. G. CADOGAN and P. G. HIBBERT* IT is well known1 that N-nitrosoacetylarylaminesin aromatic solvents rearrange by way of four-mem- bered intermediates to esters of diazoic acids which arylate the solvent by way of aryl radicals to give the corresponding biaryl and acetic acid. N=O Yb PhH Ar-N-Ac -ArN:N.OAc -3 ArPh + N,+ HOAc Certain aspects of the reactions have yet to be adequately explained however e.g. the formation of acetic acid in high yield the very low accountancy of methyl radicals and carbon dioxide (which would arise by decomposition of free acetyloxy-radicals) and absence of products (aryl acetates) of substitu-tions of the latter in the aromatic solvent.2 Cadogan Hey and William~,~ while noting that p-t-butyl-N-nitrosoacetanilidebehaved normally on decomposition in benzene to give 4-t-butylbiphenyl reported that the corresponding reaction of the o-isomer was anomalous in that the major product was an ester or mixture of esters believed to be the t-butylphenyl acetates.The anomalous nature of the reaction was subsequently confirmed by Rondestvedt and Blanchard;4 neither group offered an explana- tion. It is now possible to advance an explanation of the behaviour of the o-t-butyl derivative. In this case it is assumed that rearrangement of the nitroso-com- pound gives the cis-diazoate. Huisgen has shown that in certain cases the trans-diazoate is f~rmed.~ The formation of the cis-isomer though less likely cannot be precluded in the case of simple nitroso- acylarylamines however.Examination of scale models (Dreiding Stereomodels) shows that the presence of an o-t-butyl group greatly increases the possibility of formation of the cis-isomer. It is further assumed that the bulk t-butyl group constrains the intermediate diazoacetate in such a way that con- certed decomposition occurs to give 3-t-butylbenzyne and acetic acid. It is not possible to distinguish between this and the alternative stepwise homolytic process But 0, *OAc+N * St. Salvator’s College University of St. Andrews St. Andrews Fife. Williams “Homolytic Aromatic Substitution,” Pergamon Press 1959; Huisgen Annulen 1951 573 163.Cf. Ruchardt and Merz Tetrahedron Letters 1964 2431. Cadogan Hey and Williams J. 1954 3352. Rondestvedt and Blanchard J. Amer. Chem. Suc. 1955 77 1771. Huisgen Annulen 1951 574 171. OCTOBER 1964 In either event the aryne and acetic acid which are created in close proximity would be expected to react to give a mixture of o-and rn-t-butylphenyl acetates. The presence in the nitrosoacetanilide of ortho-groups smaller than t-butyl would result in less constraint leading to the formation of the trans-diazoate which would decompose in the normal fashion. The decomposition of o-t-butyl-N-nitrosoace-tanilide in benzene has now been reinvestigated in ing t-butylphenols. The g.1.c.results were checked by analyses on widely different column packing and with different conditions. The formation of 3-t-butylbenzyne has been further confirmed by the isolation of 2-t-butyltriptycene (9%) in addition to o-and rn-t-butylphenyl acetate (20%) from the reaction of o-t-butyl-N-nitroso-acetanilide with anthracene in benzene. The struc- ture of the 2-t-butyltriptycene was confirmed by comparison of its n.m.r. and U.V. spectra with those Of triptycene The Structure of Trisdiaminecobalt(m)Ion-pairs By S. F. MASONand Miss B. J. NORMAN* WERNER'S observation1 that the molecular rotation of a dissymmetric metal complex ion is affected by the gegenion has been studied recently2s3 in connection with outer-sphere co-ordination.The molecular rotation is the sum of contributions from the optic- ally-active electronic transitions of the molecule and it is now found that each circular dichroism band of (+)-Co(en),* and of (+)-and (-)-Co(+pn)?+ in aqueous solution is changed by the addition of polarizable anions (Figs. 1 and 2). The effects are larger the greater the charge of the anion and they are qualitatively similar for trigonal and tetrahedral oxyanions at low concentration. In terms of the rotational strength R measured by the circular dichroism band area the changes due to an increase in anion concentration consist in the case of (+)-Co(en),3+of a decrease in R(EJ and a compensating increase in R(A,) an enhancement of R(E,) and the development of a new circular dichroism band and unpolarized absorption in the 2600 A region (Fig.1). Analysis of the 2600 8 absorption by standard methods4 indicates the formation of a 1 :1 ion-pair. With (+)-Co(+pn),* but not (-)-Co( +~n),~+, quantitatively similar spectroscopic changes are observed. In the case of (-)-Co( +pn),3+ the form of the variation of R(EJ + R(A2) with anion concentration is different (Fig. 2) the two bands being unresolved in this complex and no circular dichroism absorption is measurable at 2600 A although an unpolarized band is found at that wave- h @) 5OOO4000 3000 2500 I I I-' I II 1 20,OOO 30,000 40,000 'V (cm? ) FIG.1. The electronic spectrum of (+)-Co(en) (C10J3 ; unpolarized absorption ni water and -.-.-.in O-O5~-phosphate: circuIar dichroism ---in water and... . . ..... in O-O5~.phosphate. * Chemistry Department The University of Exeter. Present address School of Chemical Sciences University of East Anglia Norwich. Werner Ber. 19J2 45 121. a Albinak Bhatnagar Kirschner and Sonnessa Canad.J. Chem. 1961 39 2360. Larsson Acta Chem. Scand. 1962 16 2267. Evans and Nancollas Trans. Faraday Soc. 1953 49 363; Taube and Posey J. Arner. Chem. Soc. 1953,75 1463; ibid. 1956 78 15. length. The presence or absence of circular dichro- ism at 2600 8,indicates that an oxyanion and (+)-C~(en),~+or but not (-)-Co( +pn):+ (+)-Co( +~n),~+ have a preferred mutual orientation in the ion-pair. r 1 0-05 0.10 FIG.2. The variation with phosphate-ion con-centration of the rotational strengths R of the electronic transitions given by (+)-C~(en),~+ (full lines) and by (-)-Co( +pn),,+ (dashed line).The symmetry representations refer to the bands illustrated in Fig. 1. The lel and ob conformations of the chelate rings are fixed in (+)-and (-)-Co(+pn)z+ re~pectively.~ In the fef conformation which is adopted by Co(en),3+ in the crystals with known structures,G two sets of three N-H bonds have a polar direction nearly parallel to the three-fold axis (C,) and three sets of two N-H bonds are directed perpendicular to the C3axis. In the ob conformation no two N-H bonds have a common orientation. Thus the pro- bable structure of the ion-pair formed by oxyanions with (+)-Co(en)?+ or (+)-Co(+pn):+ is (I) for the methyl groups of the latter complex ion would im- pede the formation of hydrogen bonds directed perpendicular to the C3 axis.The absorption and circular dichroism bands of the ion-pair (1) at 2600 A are due to the transfer of charge from the anion to the cation. The method' of Wolfsberg and Helmholz shows that the highest occupied orbital of trigonal and tetrahedral OXY-anions with a closed shell has A symmetry in the C3group of the ion-pair (I) consisting of an anti- bonding combination of oxygen 2p lone-pair PROCEEDINGS orbitals directed tangentially to the circle described by the radius vector from the C3axis to the hydrogen- bonded oxygen atoms. The lowest unoccupied orbitals of Co(en),3+ are the dr orbitals with E symmetry in the group C,.Thus the charge transfer (C.T.) transition has moments directed perpendicular to the C3 axis and it mixes with other transitions of E symmetry. In particular part of the magnetic moment of the E transition is borrowed and shared with the Eb transition diminishing I?(&) en-hancing R(E,) and giving a non-zero R(C.T.). In the free randomly-orientated (+)-Co(en)?+ ion R(E,) and R(A,) which are opposed in sign mutually cancel* to within 5% so that the decrease in R(E,) due to ion-pairing results in a commensur- ate increase in R(A2). By other mechanisms the exact compensation of the observed changes (Fig. 2) in R(EJ and R(A2)would not be generally expected 0 H' At low concentrations the effect of sulphate and thiosulphate is similar to that of phosphate (Fig.2) but with these anions at concentrations > 0.2~ the previous changes are reversed and the circular dichroism spectrum of (+)-C~(en),~+ reverts to that of the free cation owing to the breakdown of the specific orientation of the ion-pair (I) in the denser ionic atmosphere. At the same time a small increase in the sum R(E,) + R(A& is found an effect observed additionally with halide and hydroxide at all concentrations. Perchlorate at any practicable concentration has virtually no effect upon the circu- lar dichroism spectra of Co(m) complexes in aqueous solution. (Received August 12th 1964.) 6 Corey and Bailar J. Amer. Chem. SOC.,1959 81 2620. 6 Nakatsu Saito and Kuroya Bull.Chem.Soc. Jupan 1956 29 428; Nakatsu Shiro Saito and Kuroya ibid. 1957 30. 158 Nakatsu. ibid. 1962. 35. 832. Woifsberg and Hel;nhol< J. Chem. Phys. 1952 20 837. 8 McCaffery and Mason,Mol. Phys. 1963 6 359. OCTOBER1964 341 -~ ~~ The PhotochemicaI Formation of Trifluoromethoxyl Fluoride By P. J. AYMONINO* TRIFLUOROMETHOXYL FLUORIDE (preparedl from methanol or carbon monoxide or carbonyl fluoride and fluorine) is one of the few thermally stable substances containing fluorine bonded to oxygen. To determine whether fluorine atoms are able to react with carbonyl fluoride even at room tempera- ture we have photolysed fluorine molecules in the presence of carbonyl fluoride. Fluorine and carbonyl fluoride do not react in the dark at room tempera- ture.Carbonyl fluoride was prepared before each experiment in a quartz vessel by adding fluorine slowly to carbon monoxide Infrared spectroscopy spectra showed that carbon dioxide and traces of silicon tetrafluoride were the only impurities present in carbonyl fluoride so prepared. Mixtures of carbonyl fluoride and an excess of fluorine (1 :2 to 1:3) below atmospheric pressures were irradiated for several hours at 35"c with a mercury high-pressure quartz lamp in a quartz vessel immersed in a water-thermostat made of Pyrex glass (to cut off light of too-short wavelength). At the end of the reaction the pressure decrease was about 75 % of the value expected from the stoicheiometry of the reaction FzCO + F2 = F3COF.Trifluoromethoxyl fluoride was the main product. It was identified by i.r.-spectroscopy and gas density after its separation by low-temperature distillation from small quantities of bistrifluoromethyl peroxide carbon dioxide silicon tetrafluoride and traces of carbonyl fluoride and carbon tetrafluoride. Trifluoro- methoxyl fluoride accounted for SO% of the original carbon monoxide as determined iodometrical1y.l As carbonyl fluoride does not absorb at the wavelength employed fluorine atoms must be re- sponsible for the formation of the trifluoromethoxyl fluoride and bistrifluoromethyl peroxide by schemes of the type (1) F2 + hv = 2F (2) F + COFz = F3C0 (3a) F3C0 + Fz = F3COF + F (36) 2F3C0 = (F3C),OZ rI rifluoromethoxyl radicals are also produced by the photolysis of trifluoromethoxyl fl~oride.~ (Received February loth 1964.) * Instituto Superior de Investigaciones Facultad de Quimica y Farmacia Universidad Nacional de La Plata La Plata Republica Argentina.Kellogg and Cady J. Amer. Chem. SOC.,1948,70 3986. Heras Arvia Aymonino and Schumacher Z. phys. Chem. 1961,28,250. * Porter and Cady J. Amer. Chem. SOC.,1957,79,5625; Allison and Cady Ibid. 1959 81,1089; Pass and Roberts Inorg. Chem. 1963 2 1016; and our own preliminary results. The Existence of Two Crystalline Forms of Anhydrous Copper(I1) Nitrate By N. LOGAN W. B. SIMPSON, and S. C. WALLWORK* DURING the determination of the crystal structure of anhydrous copper(r1) nitrate,l two types of single crystal X-ray photograph were recognised.Samples of the substance giving each type of photograph have now been studied more extensively. Since both substances gave correct analyses for copper(II) nitrate yet differed in their X-ray powder photo-graphs and infrared spectra they must simply be two different crystalline modifications. It is now realised that the published infrared data2 and some e.s.r. measurements3 relate to what is now termed the /%form whereas the crystal structure work so far reported relates to the a-form. We therefore give below some characteristic data by means of which the two forms may be distinguished. a-Cu(NO,),. This is obtained as a crystalline powder by heating the adduct CU(NO~)~,N~O~ in vacuo to about 100".Attempts to recrystallise this form by sublimation have always resulted in a mix- ture of the two forms. The most significant feature of the infrared spectrum of the a-form is the absence of any strong absorption bands above 1510 cm.-l and the appearance of a band at 1435 cm.-l. Lines in the X-ray powder pattern (d values in A and qualitative intensities; Cu-K radiation A = 1.542A) down to d = 1-7OA are as follows 5.57~~; 4.31~;4.14s; 3.78~; 3.54~; 3.41m; 3.33~; 3.08mw; 2.99mw; 2.79s; 2.69~; 233m; 2-42m; 2.34m; 2-30m; 2-22m; 2-16ms; 2.08~; 2.04~; 2.01m; 1.95mw; 1.92~; 1.87mw; 1-83m; 1.77~~; 1.71m. * Department of Chemistry The University Nottingham. 1 S. C. Wallwork Pruc. Chem. Suc. 1959 31 1 ;S. C. Wallwork and W. E. Addison J.in the press. * C. C. Addison and B. M. Gatehouse J. 1960 613. a S. J. T. Owen K. J. Standley and A. Walker J. Chem. Phys. 1964,40 183; E. A. Boudreaux private communica- tion. PROCEEDINGS /?-CU(NO,)~. This is obtained as a single phase by sublimation of the a-form at 200" in vacuo. The infrared spectrum does not show the band at 1435 cm.-l but has absorption above 1510 cm.-l including strong bands at 1526 and 1580 cm-.l. The powder data (as above) are 6.66mw; 6.30mw; 5-91m; 4.83~~; 4-02ms; 3-74m; 354m; 4.64~~; ~ 1.97~;1.92~; 149mw; 1.85~; 1.80~; 1.71~. At room temperature both forms are stable for long periods in the absence of moisture but at elevated temperatures the a-form is transformed into the /%form very slowly at about 100" but rapidly at 150" and above.Details of the infrared spectra of both forms of copper(@ nitrate will be published 34.4~; 3.14m; 2.97~; 2.91~;2.74~; separately as will the crystal structure of the 3.30m; 3.22~~; B-form now under investigation. 2.59m;2.53~;2-45~;2.40mw;2-36~;2.32~;2-26~; 2.22~; 2.19~; 2-13mw; 2.10mw; 2.08~; 2-02mw; (Received September 1Sth 1964.) N. Logan and W. B. Simpson to be published. The Oxidation of Carbohydrate Derivatives with Ruthenium Tetroxide By P. J. BEYNON,P. M. COLLINS,and W. G. OVEREND* WEfind that oxidation of suitably protected methyl glycosides with ruthenium tetroxidel in carbon tetrachloride at -20" during 1-4 hr. gives glyculo- pyranosides. Generally yields are much better than those obtained when the chromium trioxide-pyridine complex (the more usual oxidant) is em- ployed.2 The following oxidations with ruthenium tetroxide have been achieved methyl 3,4-0-iso- propylidenep-L-arabinoside 3 methyl 3,4-O-iso- propylidene-p-L-erythro-pentulopyranoside;2a methyl 6-deoxy-2,3-0-isopropylidene-cc-~-mannopyranoside 4 methyl 6-deoxy-2,3-0-isopropylidene-a-~-lyxo-P hexulopyranoside;2b methyl 6-deoxy-3,4-0-isopro- pylidene-a-L-galactoside + methyl 6-deoxy,3,4-0- isopropylidene-a-L-lyxo-hexulopyranoside2C (these glyculopyranosides were identical with samples obtained by oxidations with CrO,-C,H,N); methyl 4,6-O-benzylidene-2-deoxy-a-~-lyxo-hexopyranoside (I), -.t methyl 4,6-0-benzylidene-2-deoxy-a-~-threo-3-hexulopyranoside(11){ m.p.132-1 34" [aID+ 150"; oxime m.p. 219-220" [aID+ 257"; reduction (Pt0,-H,) regenerated (I) (70%)). Ruthenium tetroxide has several advantages for the preparation of glyculopyranosides and can be used when Cr0,-C,H,N is unsatisfactory. For example earlier attempts to carry out the conversion (I)-+ (TI) with CrO,-C,H,N at 80" had led to formation of the pyranodioxin (JII) (3373 m.p. 165-166" [a],+ 185";Amax. 266 m,u (E 9-9 x lo3) (in EtOH); vmax. 1600 1680 cm.-l (C=C C=O conj.); T 5.5 (vinyl H) 3.6 (H-C=C-C=O) by elimination of methanol in addition to oxidation. The structure of this compound was based on its elemental analysis the physical evidence liberation of benzaldehyde on acidification decolorisatjon of permanganate consumption of hydrogen (3.9 mol.) in the presence of palladium on charcoal and on its formation from compound (II) with elimination of methanol by heating it for 0.5 hr.in pyridine which is 0.1~ in either perchloric acid or hydrochloric acid (in pyridine alone the initial material was recover- able). Noyce et aL5 have shown that the acid- 99-42 catalysed dehydration of a P-hydroxy-ketone can proceed via either an intermediate enol or by an El mechanism either of which could be operative in the conversion (I) -(111). Whichever mechanism is operating it is clear that this easy elimination which prevents the isolation of (11) during the oxida- * Department of Chemistry Birkbeck College (University of London) Malet Street London W.C.l.Djerassi and Engle J Amer. Chem. SOC. 1953 75 3838; Berkowitz and Rylander ibid. 1958 80 6682; Nakata, Tetrahedron 1963 19 1959. (a)Burton Overend and William Chem. and Ind. 1961 175; (b) Gough and Williams unpublished results; (c) Collins and Overend Chem. and Ind. 1963 375; (d) Theander Adv. Carbohydrate Chem. 1962 17 264; (e) Krosso, Weiss and Reichstein Helv. Chim. Acta 1963,46 2538. Foster Overend and Stacey J. 1951 974. 4 Schoolery and Rogers J. Amer. Chem. SOC.,1958 80 5121. 6 Noyce and Reed J. Amer. Chem. Soc. 1958 80,5539; Noyce King Lane and Reed J. Amer. Chem. SOC.,1962 84 1638. OCTOBER 1964 tion of (I) with CrO,-C,H,N does not occur if ruthenium tetroxide is the oxidant. Examples of the oxidation of a hydroxyl group attached to a furanoid ring are limited.g Theanderec obtained a product in small yield from the oxidation of di-0-isopropylidene-D-glucofuranose.Oxidation occurred at G-3 with concomitant loss of the 5,6-0- isopropylidene residue.We find that di-0-isopro- pylidene-D-glucofuranose is oxidised in 80 % yield cleanly by ruthenium tetroxide to give 1,2:5,6-di-O- isopropylidene-a-~-ribo-3-hexulofuranose (IV) b.p. 97"/0-01 mm. [aID+ 107" [hydrate m.p. 109- 112" [a],+ 45"; oxime m.p. 103-104" [aID+ lSO"]. This compound is noteworthy because (i) it affords ~-allose' (70X crude containing a small amount of glucose;' 30% pure) on reduction with lithium aluminium hydride and subsequent acid hydrolysis; and (ii) ~-ribo-3-hexulose has been claimed8 as a constituent of a disaccharide found in Agrabacterium tumefaciens a tumour-producing organism.Unless otherwise stated [a] refer to CHCI and infrared spectra were determined with KBr discs. Satisfactory analyses have been obtained for all crystalline compounds. (Received August 1 lth 1964.) See (a) Ishidate Tamura and Kinoshita Chem. Pharm. Bull. (Tokyo) 1962,10,1258; (b) Oka and Wada Yukuguku Zasshi 1%3,83,890 (Chem. Ah. l964,60,1825d); (c)Theander Acta Chem. Scad. l963,17,175J. Phelps and Bates J. Amer. Chern. Soc. 1934 56 1250. Fukui and Hochster J. Amer. Chem. SOC.,1963 85 1697. The Crystal Structure of the Photodimer of l-Methyl-2-pyridone By MICHAEL LAING* WHENan aqueous solution of 1 -methyl-2-pyridone is irradiated with ultraviolet light a unique 1,6dimer is f0rmed.l The results of an n.m.r.study implied that this molecule is a centrosymmetric tricyclic octadiene derivative,2 and inspection of a model indicated that some very short intramolecular non- bonded interactions should be present. A sample of the material was supplied by Dr. L. A. Paquette and needle-like crystals were obtained from M ethyl acetate at 0". ~2N202H1,; = 218; mono- clinic a = 7-45,b = 11.53 c = 7.50 A = 127.95"; Dm = 1.425; 2 = 2; space group P2,/c implying molecular symmetry is 1. The structure was solved via the sharpened three- dimensional Patterson function and refined aniso- tropically to an R-value of 0.089 for 487 observed reflections (1 164 recordable with Cu-K radiation). The hydrogen atoms were located from a three-dimensional difference synthesis and were included in the later stages of refinement with isotropic tem- perature factors.The bond lengths with standard deviations of about 0.015 A are shown in the Figure which is a projection of the molecule down a. The sp3C-sp3C bond of 1-60 A is significantly stretched from the usual 1.54 A. This increase is due to the strain caused by the very close contacts between the two pyridone rings; each of the values * University of California Los Angeles 24 California. 2-68 2-71 and 2.72 8 is distinctly shorter than 3.4 %i which is the sum of the van der Waals radii for the pairs of atoms concerned. The remaining bond lengths are quite normal. This molecule seems to be even more strained than any of the paracyclophane structures that have been rep~rted.~ In a recent redetermination of the structure of 2,2-paracyclophane,4 values of 1.57 and 2.79 were obtained for distances analogous to those mentioned above.(Received August 27th 1964.) Taylor and Paudler Tetrahedron Letters 1960 No. 25 1. Slomp MacKellar and Paquette J. Amer. Chem. SOC.,1961 83 4472. Coulter and Trueblood Actu Cryst. 1963,16,667; Lonsdale Milledge and Rao Proc. Roy. Soc. 1960 A 255,82; Hanson Actu Cryst. 1962 15 956. * Bekoe and Trueblood private communication 1964. PROCEEDINGS NEWS AND ANNOUNCEMENTS Meetings for the Presentation of Communications. -The Council has agreed to provide opportunities for the presentation of Communications at scientific meetings.The proposal will be introduced on a small scale at the Anniversary Meetings in Glasgow on April 7-9th 1965 to be followed by a further meeting to be held in Nottingham on September 21st-22nd 1965. It is hoped that chemists in this country and particularly those in the younger age groups will welcome this opportunity of getting themselves and their work appreciated. In the past formal meetings for the reading of papers have been held in London and occasionally in the provinces but these have recently not been popular. It is believed however that one- or two- day meetings at which there will be an opportunity for the presentation and discussion of the most recent results i.e. the kind of work that would be published by the Society as Communications will be welcomed by the chemical world generally.The selection of papers will be made as late as possible in order to give speakers an opportunity to include their latest work. There will be no direct publication from the meeting and authors will be free subsequently to publish as they wish. Fellows who wish to submit a paper for the meet- ing in Glasgow should apply not later than Saturday January 30th 1965 on the forms available from the General Secretary. A short abstract will be required at this time to assist in the selection of papers but those whose applications are accepted may if they wish substitute an amended abstract at any date up to Monday March lst 1965. The circulated abstracts distributed a few days before the meeting will be reproduced directly by offset printing from the authors’ own manuscripts which must there- fore be carefully prepared to the specifications available with the application form.Local Representatives.-The Council has approved the following changes of Local Representatives Canberra Australia Prqfessor A. Albert in place of Projessor G.M. Badger Glasgow .. . . Dr. D. W. A. Sharp in place of Dr. H. C. S. Wood Election of New Fellows.40 Candidates were elected to the Fellowship in September 1964. Deaths.-We regret to announce the deaths of the following:Mi-. A. F. Ah (2.8.64) a Fellow for over 50 years; Mr. F. W. Edwards (10.5.64) formerly Analytical and Consulting Chemist for the City of Westminster; Dr.J. Farquharson (22.8.64) a Con- sultant at Beecham Group Limited; Professor F. H. Garner (1 8.9.64) Emeritus Professor of Chemical Engineering at the University of Birmingham; Dr. R. N. Lacey (31.7.64) of the British Petroleum Research Centre; Dr. R.Lessing (2.9.64) who was a Consulting Chemist and Chemical Engineer; Mr. G. A. Turner (26.3.64) of Worcester. Meldola Medal.-This Medal is the gift of the Society of Maccabaeans and is normally awarded annually. The next award will be made early in 1965 to the chemist who being a British subject and under 30 years of age at December 31st 1964 shows the most promise as indicated by his or her published chemical work brought to the notice of the Council of the Royal Institute of Chemistry before December 31st 1964.No restrictions are placed upon the kind of chem-ical work or the place in which it is conducted. The merits of the work may be brought to the notice of the Council either by persons who desire to recom- mend the candidate or by the candidate himself by letter addressed to The President The Royal Insti- tute of Chemistry 30 Russell Square London W.C. 1 the envelope being marked “Meldola Medal”. The letter should be accompanied by six copies of a short statement on the candidate’s career (date of birth education and experience degrees and other qualifications special awards etc. with dates) and a list of titles with references of papers or other works published by the candidate independently or jointly.Candidates are also advised to forward one reprint of each published paper of which copies are available. The Beilby Medal and Prize 1965.-Awards from the Sir George Beilby Memorial Fund are made by the Administrators of the Fund representing the Royal Institute of Chemistry the Society of Chem- ical Industry and the Institute of Metals. Sir George Beilby had been President of each of these three bodies and they jointly sponsored the appeal for subscriptions whereby the Fund was raised as a memorial to him after his death in 1925. The Beilby Medal and Prize which consists of a gold medal and a substantial sum of money is specified as being “For Advancement in Science and Practice”. Such an award is now being offered annually.The awards are made to British investigators in science in recognition of independent original work of exceptional merit carried out continuously over a period of years and involving the development and application of scientific principles in any field related to the special interests of Sir George Beilby ix. in chemical engineering fuel technology or metallurgy in their modern interpretations. The awards are in- tended as an encouragement to younger men and women (preferably under age 40) who have done OCTOBER 1964 distinguished work of practical significance in any of these fields. Consideration will be given in due course to the making of an award from the Fund in 1965. Out-standing work of the nature indicated may be brought to the notice of the Administrators either by persons who desire to recommend the candidate or by the candidate himself not later than December 31st 1964 by letter addressed to The Convener of the Administrators Sir George Beilby Memorial Fund The Royal Institute of Chemistry 30 Russell Square London W.C.1. The letter should be accompanied by nine copies of a short statement on the candidate’s career (date of birth education and experience degrees and other qualifications special awards etc. with dates) and of a list of titles with references of papers or other works published by the candidate independently or jointly. Photographic copies of these documents are acceptable. Candidates are also advised to forward one reprint of each published paper of which copies are available.American Chemical Society Publications.-A long established reciprocal agreement allows Fellows of the Chemical Society not being Members of the American Chemical Society to subscribe to the publications of the latter Society at a discount of 10% from the non-members’ rates. No discount is available on the Chemical Abstracts Service how- ever. Fellows wishing to take advantage of this con- cession should apply to the American Chemical Society 11 55 Sixteenth Street N.W. Washington D.C. 20036 U.S.A. Fellows wishing to apply for membership of the American Chemical Society may obtain forms of application from the General Secretary. I.U.P.A.C. Committee on the Teaching of Chem-istry.-The International Union of Pure and Applied Chemistry has recently established a permanent Committee on the Teaching of Chemistry.The present membership consists of Professor J. Benard Professor J. A. Campbell Professor W.A. Noyes Jr. Professor M. Oki Professor 0. Reutov Professor G. M. Schwab with Projessor R. S. Nyholm as Chair- man and Dr. P. Sykes as Secretary. At its first meeting in Basle the Committee defined its role as (a) To disseminate information concerning chemical education at all levels throughout the world. (b) To offer advice through public statements and by direct contact with interested bodies on the kind of activity which it feels will ensue the development of a modern approach to the teaching of chemistry.Towards these ends the Secretary would be pleased to hear of any activity which might be of interest to the members of the Committee. His address is the University Chemical Laboratory Lensfield Road Cambridge. The Welwyn Hall Research Association.-Whiting and Industrial Powders and Chalk Lime and Allied Industries have merged to form a new co-operative industrial research organisation. Mr. D. B. Jones will be the Chairman of the new Association Mr. D. C. Soul the first Director of Research and Mr. G. E. Bessey a consultant. Welwyn Hall Research Association will occupy the existing joint premises in Church Street Welwyn Hertfordshire and during the next five years it aims to spend over f400,000 in serving its member firms.Further details of the new Association and its work can be obtained from the Secretary or the Technical Information Officer. Symposium.-A Symposium on Oxidation in Organic Chemistry will be held in Manchester on March 23rd-24th 1965. Further enquiries should be addressed to Dr. G. Holt Department of Chem-istry Manchester College of Science and Technology Manchester 1. Personal.-Professor G. M. Badger has been appointed Professor Emeritus in the Department of Chemistry the University of Adelaide. Dr. J. Carnduf formerly of Harvard University has taken up a Research Fellowship at the University of Strasbourg Strasbourg France. Mr. B. E. P. Clement has been appointed Deputy Chemist and Bacteriologist to the North Bedford- shire Water Board Bedford.Dr. B. R. James formerly of A.E.R.E. Harwell has been appointed Assistant Professor in the Chemistry Department at the University of British Columbia Canada. Dr. A. D. Jenkins has been appointed to a Senior Lectureship in Chemistry in the University of Sussex. The D.S.I.R. has made a grant of 21,450 to Mr. N. Jones and Mr. E. Catterall of the Lanchester College of Technology Coventry for the purchase of a gas chromatography unit and accessories in connection with their investigations of Friedel-Crafts acylation of alkenes and cycloalkenes and studies of the stereo- regular polymerisation of dienes and olefin oxides. Dr. V. E. Malpass has been appointed Senior Research Chemist with the Marbon Chemical Divi- sion of Borg-Warner Corporation West Virginia U.S.A.The title of Professor of Chemistry has been con- ferred on Dr. D. J. Millen in respect of his post at University College. Dr. W. McCrae formerly Research Chemist at Lederle Laboratories New York U.S.A. has been appointed an Imperial Chemical Industries Research Fellow at the University of Cambridge. Mu. 1. T. McWaZter formerly Industrial Chemist at the Atomic Energy Research Establishment Harwell has been appointed Lecturer in Inorganic Chemistry at Robert Gordon’s Technical College Aberdeen. Dr. T. J. Painter has been appointed Lecturer in Biochemistry at the Royal Free Hospital School of Medicine London from April lst 1965. Professor G. W.PeroZd Professor of Chemistry at the University of South Africa has been appointed to the Chair of Organic Chemistry at the University of the Witwatersrand as from January lst 1965.He will succeed Professor D. G. Backeberg who has been on the staff of the University for more than 40 years and was appointed Professor of Organic Chemistry and Head of the Department in 1955. Dr. S. K. Pradhan formerly of the Worcester Foundation for Experimental Biology Shrewsbury Massachusetts has been appointed Head of the Chemistry Department University of Shivaji India. Dr. A. Robson formerly of the Wool Industries Research Association in Leeds has been appointed Professor of Fibre Science at the University of Leeds. Dr. B. Rose has been appointed to a Senior London Thursday November 19th 1964 at 6 p.m.Discussion Meeting on Free Radicals. To be held in the Rooms of the Society Burlington House W. 1. Aberdeen Thursday November 12th 1964 at 8 p.m. Lecture “The Chemistry of Oxidative Phosphoryla- tion,” by Dr. V. M. Clark M.A. Joint Meeting with the University Chemical Society to be held in the Chemistry Department The University. Tuesday November 24th at 8 p.m. Lecture “The Substituent Effects of Positive Poles in Aromatic Nitration,” by Dr. J. H. Ridd. Joint Meeting with the Royal Institute of Chemistry and the Society of Chemical Industry to be held in the Biochemistry Lecture Theatre Marischal College. Aberystwyth Thursday November 12th 1964 at 5 p.m. Lecture “Topographical Studies of Crystal Sur- faces,” by Dr.J. M. Thomas. Joint Meeting with the University College of Wales Chemical Society to be held in the Edward Davies Chemical Laboratory. PROCEEDINGS Lectureship in Chemistry at the University of Nigeria. Dr. C. E. Stickings has been appointed Senior Lecturer in the Department of Biochemistry at the Imperial College of Science and Technology London. Dr. B. J. Wakefield has been appointed Lecturer in the Department of Chemistry and Applied Chemistry at the Royal College of Advanced Technology Salford Lancashire. Dr. S. Walker Reader in the Chemistry Depart- ment of the College of Advanced Technology Birmingham has been awarded the degree of D.Sc. by the University of London. Dr. H. Watts,formerly Senior Lecturer in Applied Physical Chemistry at the South Australian Institute of Technology has joined the Exploratory Research Laboratory of Dow Chemical of Canada Limited Ontario Canada.Dr. R. 0.Williams formerly Technical Officer with Imperial Chemical Industries Limited has been appointed Lecturer in Organic Chemistry at the Technical College at Portsmouth. Dr. C. J. Wormald has been appointed Assistant Lecturer in Chemistry at the University of Bristol. Birmingham (Joint Meetings with the University Chemical Society to be held in the Chemistry Department The University.) Friday November 20th 1964 at 4.30 p.m. Lecture “Ways of Promoting Chemical Reactivity,” by Dr. G. Baddeley. Friday December 4th at 4.30p.m. Lecture “Synthetic Sex Hormones,” by Professor A.J. Birch D.Phil. F.R.S. Brighton (Joint Meetings with the University Chemical Society to be held in the Chemical Laboratory The University of Sussex.) Monday November 9th 1964 at 5.15 p.m. Lecture “Optical Rotatory Dispersion,” by Profes- sor W. Klyne M.A. Ph.D. Monday November 23rd at 5.15 p.m. Lecture “Fluoroalicyclic Compounds,” by Professor J. C. Tatlow Ph.D. F.R.I.C. Bristol (Joint Meetings with the Society of Chemical Industry and the Royal Institute of Chemistry to be OCTOBER 1964 held in the Department of Chemistry The Univer- sity unless otherwise stated.) Thursday November 19th 1964 at 5.30 p.m. Lecture “Some Effects of Molecular Orientation in Gases and Liquids,” by Dr. A. D. Buckingham M.A.Also joint with the Student Chemical Society. Thursday November 26th at 7.30 p.m. Social Evening to be held at Cheltenham. Thursday December 3rd at 6.30 p.m. Lecture “Aerosols-The Development of Pres-surised Packaging,” by Mr. P. Dyson B.A. B.Sc. Cambridge (Joint Meetings with the University Chemical Society to be held in the University Chemical Laboratory Lensfield Road.) Friday November 6th 1964 at 8.30 p.m. Lecture “The Stabilisation of Low-valent States of Transition Metals by Tertiary Phosphines,” by Professor J. Chatt Sc.D. F.R.S. Friday November 20th at 8.30 p.m. Lecture “Some Recent Studies on the Biosynthesis of Alkaloids,” by Professor D. H. R. Barton D.Sc. F.R.S. Cardiff Monday November 16th 1964 at 5 p.m. Lecture “Some Applications of Electron Spin Resonance Spectroscopy in Elucidating Reaction Mechanisms,” by Dr.R. 0. C. Norman B.A. To be given in the Department of Chemistry University College Cathays Park Cardiff. Dublin Friday November 27th 1964 at 7.45 p.m. Lecture “Dissociation of Energies Ionisation Potentials and Electron Affinities of Molecules and Radicals,” by Professor W. C. Price F.R.S. Joint Meeting with the Werner Society to be held in the Department of Chemistry Trinity College. Durham (Joint Meetings with the University Chemical Society to be held in the Science Laboratories South Road.) Monday November 9th 1964 at 5 p.m. Lecture “Multiple Bonds in Inorganic Chemistry,” by Dr. M. F. Lappert F.R.I.C. Monday November 23rd at 5 p.m.Official Meeting and Lecture “Chemical Methods of Attaining High Temperatures,” by Professor P. Gray M.A. Ph.D. Monday November 3Oth at 5 p.m. Lecture to be given by Dr. M. C. Whiting M.A. Wednesday December 2nd at 5.15 p.m. Lecture “Applications of Nuclear Magnetic Reson- ance Spectroscopy,” by Dr. J. E. Page F.R.I.C. Edinburgh Tuesday November loth 1964 at 4.30 p.m. Lecture “Stepwise Equilibria,” by Dr. F. J. C. Rossotti M.A. Joint Meeting with the University Chemical Society to be held in the Department of Chemistry The University. Thursday November 12th at 7.30 p.m. Lecture “Modern Aspects of Structure Determina- tion,” by Professor W. D. Ollis Ph.D. Joint Meeting with the Royal Institute of Chemistry and the Society of Chemical Industry to be held in the Heriot-Watt College.Exeter (Meetings to be held in the Washington Singer Laboratories Prince of Wales Road.) Friday November 13th 1964 at 5.15 p.m. Lecture “Some Aspects of Electrophilic Aromatic Substitutions,” by Professor C. Eaborn PhD. D.Sc. Friday December 4th at 5.15 p.m. Lecture “Organic Semiconductors,” by Professor D. D. Eley O.B.E. F.R.S. Glasgow Thursday November 19th 1964 at 4 p.m. Lecture “Atomic and Molecular Events at the Surfaces of Metals,” by Professor F. C. Tompkins Ph.D. F.R.S. Joint Meeting with the Alchemists’ Club to be held in the Chemistry Department The University. Hull (Joint Meetings with the University Students Chemical Society to be held at the Lecture Theatre The University.) Thursday November 12th 1964 at 4 p.m.Lecture “Chemical Methods of Attaining High Temperatures,” by Professor P. Gray M.A. Ph.D. Thursday November 26th at 4 p.m. Lecture “Some Aspects of the Chemistry of Titan-ium and Neighbouring Elements,” by Dr. G. W. A. Fowles. Leicester Thursday November 12th 1964 at 5 p.m. Lecture “Spectroscopic Aspects of Optical Rotary Power,” by Professor S. F. Mason M.A. D.Phi1. Joint Meeting with the Chemical Society of Leicester College of Technology to be given at the College of Technology. Liverpool Thursday November 26th 1964 at 5 p.m. Lecture “The Role of Organometallic Compounds in the Development of Co-ordination Chemistry,” by Professor F. G.A. Stone M.A. Sc.D. Joint Meeting with the Society of Chemical Industry the Royal Institute of Chemistry and the University Chemical Society to be held in the Donnan Laboratories The Chemistry Department The University. Manchester Thursday November 12th 1964 at 6.30 p.m. Lecture “The Corrin Ring System,” by Professor A. W. Johnson M.A. Ph.D. A.R.C.S. To be given in Theatre R/H 10 Renold Building Manchester College of Science and Technology. Northern Ireland Tuesday November 3rd 1964 at 7.45 p.m. Lecture “The Nature of Reactive Intermediates in Cationic Polymerisation,” by Professor D. C. Pepper M.A. Ph.D. Joint Meeting with the Royal Institute of Chemistry the Society of Chemical Industry and the Andrews Club to be held in the Department of Chemistry David Keir Building Queen’s University Belfast.North Wales Thursday November 19th 1964 at 5.30 p.m. Lecture “Some Problems in Carbohydrate Chem- istry,” by Professor E. J. Bourne D.Sc. F.R.I.C. Joint Meeting with the University College of North Wales Chemical Society to be held in the Chemistry Department University College Bangor. Norwich (Meetings to be held in Lecture Room 2 The University of East Anglia Wilberforce Road.) Thursday November 26th 1964 at 5.30 p.m. Tilden Lecture “Experiments with Orientated Mole- cules,” by Dr. A. D. Buckingham M.A. Thursday December 3rd at 7.45 p.m. Lecture “Metal to Metal Bonds in Inorganic Com- pounds,” by Professor R. S. Nyholm D.Sc. F.R.S. Joint Meeting with the Royal Institute of Chemistry.Nottingham (Joint Meetings with the University Chemical Society to be held in the Large Lecture Theatre the Department of Chemistry The University.) Tuesday November loth 1964 at 5 p.m. Lecture “Some Aspects of Polyacetylene Chem- istry,” by Professor Sir Ewart Jones D.Sc. F.R.S. Tuesday November 24th at 5 p.m. Lecture “Symmetry Structure and Spectroscopy,” by Professor A. D. Walsh M.A. Ph.D. Oxford (Joint Meetings with the Alembic Club to be held in the Inorganic Chemistry Laboratory.) Monday November 2nd 1964 at 8.30 p.m. Lecture “Experiments with Orient a ted Molecules ,’’ by Dr. A. D. Buckingham M.A. Monday November 16th at 8.30 p.m. Lecture “Gastrin a Peptide Hormone,” by Pro- fessor G. w. Kenner Ph.D.Sc.D. Reading Tuesday November 17th 1964 at 5.30 p.m. Tilden Lecture “Experiments with Orientated Molecules,” by Dr. A. D. Buckingham M.A. Joint Meeting with the Royal Institute of Chemistry and the University Chemical Society to be held in the Large Chemistry Lecture Theatre The University. Swansea (Joint Meetings with the Student Chemical Society to be held in the Chemistry Lecture Theatre University College.) Monday November 2nd 1964 at 4.30 p.m. Lecture “Some Aspects of the Chemistry of Bacterial Cell Walls,” by Professor J. Baddiley Ph.D. D.Sc. F.R.S. Monday November 9th at 4.30p.m. Lecture “The Role of Organonietallic Compounds in the Development of Co-ordinate Chemistry,” by Professor F. G. A. Stone M.A. Ph.D. Monday November 3Oth at 5 p.m.Lecture “The Hydrogen Bond,” by Dr. L. J. Bellamy. Also joint with the Royal Institute of Chemistry. Southampton Friday November 6th,1964 at 7 p.m. Lecture “The Compounds of the Inert Gases,” by Dr. R. D. Peacock. To be given in Lecture Room H9 College of Technology Portsmouth. Friday December 4th at 5 p.m. Lecture “A Chemist at Sea,” by Dr. L. H. N. Cooper F.R.I.C. To be given in the Lecture Theatre the Chemistry Department the University. Tees-side (Please note that the Lecture by Professor A. Birch on Thursday November 19th has been postponed. A new date will be announced later.)
ISSN:0369-8718
DOI:10.1039/PS9640000313
出版商:RSC
年代:1964
数据来源: RSC
|
|