摘要:

PROCEEDINGS OF THE CHEMICAL SOCIETY SEPTEMBER 1963 CENTENARY LECTURE* The Mechanism of the Enzymic Decarboxylation of Acetoacetic Acidf By F. H. WESTHEIMER (HARVARD CAMBRIDGE, UNIVERSITY MASS.,U.S.A.) DURINGthe past few years the mechanisms of several enzymic reactions have been partially and provisionally elucidated. One example comes from recent work at Harvard with the decarboxylase for acetoacetate from Clostridium acetobutylicum. The results so far obtained suggest as a working hypo- thesis that the reaction occurs by way of a Schiff base formed between enzyme and substrate. Although this hypothesis is far from proved and must be regarded as tentative the results can nevertheless most easily be organised around this idea. The evidence has been divided as follows first the mechanism of the non- enzymic decarboxylation of /3-keto-acids will be re- viewed then the purification of the enzyme will be outlined and finally the enzymic experiments will be presented which may lead to a mechanistic inter- pretation of the biochemical decarboxylation.The Non-eniymic Decarboxylation of p-Keto-acids.-The decarboxylation of acetoacetic acid is one of the simplest and most thoroughly studied1 reactions of organic chemistry CH,-COCH,.CO,H -+ CH,CO*CH + CO The mechanism which is accepted today was first put forward by Bredt in 1927; he based his scheme upon a consideration of the chemistry of ketopinic acid (I) and of camphenonic acid. Neither of these 13-keto-acids will undergo thermal decarboxylation? Bredt3 pointed out that this anomaly can be under-stood provided that the en01 of the product is an obligatory intermediate in the decarboxylation pro- cess.For ketopinic acid the required enolic inter- mediate 11,would have a double bond at the bridge- head of a mall^*^ bicyclic system and would conse- quently be intolerably strained; the decarboxylation therefore cannot occur. A similar intermediate in violation of Bredt’s rule would be required for camphenonic acid. Subsequently Bredt’s mechanism was confirmed by Kai Pedersen who studied the decarboxylation of dimethylacetoacetic acid in the presence and the absenceof bromine.6 The rate of evolution of carbon dioxide is the same whether the halogen is present or not but when it is present it is consumed at the same rate as that at which carbon dioxide is evolved; the product is the bromo-ketone.But under the mild experimental conditions of the decarboxylation iso- propyl methyl ketone is not rapidly brominated. * Delivered before the Chemical Society at the Imperial College of Science and Technology London on Jmmq 17th 1963. t This work was supported by the National Institutes of Health of the U.S. Public Health Services. Brown Quart. Rev. 1951,5 131. Oschan Annalen 1915,410,243; Komppa Ber. 1911,44 1537. Bredt Ann. Acad. Sci. Fennicae 1927,29 B A No. 2; Chem.Z. 1927,98 IT,2298; Chem. Ah. 1928,22,1152. * Prelog Barman and Zimmerman Helv. Chim. Acta 1949,32 1284. Fawcett Chem. Rev. 1950 47 245.Pedersen J. Amer. Chern. Suc. 1929,51,2098; 1936,58,240. 253 Pedersen therefore concluded that the decarboxyla- tion must proceed by way of some intermediate which rapidly absorbs bromine; the enol shown is the logical choice. CH,.CO.CMe,CO,H -f CH,-C= CMe H/ OH hr2 CH,.COCHMe CH,CO-CBrMe Bredt's mechanism was further confirmed by in- vestigations of the chemistry of dimethyloxaloacetic acid.' This compound is easily decarboxylated to a-methyl- a-oxobutyric acid; the mechanism by way H02C.C.CMe,C0,-+ H0,C.C =CMe + COz I1 I 0 0- H" (111) 4. HO,C.C.CH Me I; 0 of the enolate ion (111) is as illustrated. The ketonization of enols is catalysed by acids and bases; however when a dilute aqueous solution of dimethyl- oxaloacetic acid is allowed to undergo decarboxyla- tion in the absence of added buffers the enol is relatively long-lived and may be detected by ultra- violet spectroscopy.[Presumably the enol corres- ponding to the ion (HI) is metastable because the double bond is conjugated with the carboxyl group.] In Fig. 1 the spectrum of dimethyloxaloacetic acid (solid line) and that of ,&methyl- a-oxobutyric acid (dotted line) show the typical low absorbance around 300 rnp for aliphatic a-keto-acids. However during the decarboxylation the spectrum differs sharply from that of the starting material or of the product. A strong new band with extinction coefficient of several thousand appears at about 240 mp. Further the absorbance in the carbonyl region is actually less than that at zero time or at infinite time.On the assumption that the extinction coeffcient for the enol of #?-methyl-a-oxobutyric acid is similar to that of ethoxycrotonic acid the concentration of the enol may be calculated; when it is present in maxi-mum amount it accounts for about 50 % of the acids in solution. This estimate has been confirmed by bromine titration. Thus the intermediate postulated by Bredt and by Pedersen may actually be "seen".' The decarboxylation of dimethyloxaloacetic acid like that of oxaloacetic acid it~elf,~ is strongly pro- moted by multivalent cations. When ferric ions are used as catalystlo the course of the reaction can be followed visually. A one-to-one complex between PROCEEDINGS Wavelength (g) 0' 3:,od ' ' ' 30,000 ' Frequency (cm:') FIG.1.The ultraviolet spectra observed dariitg the decarboxylation of oxaloacetic acid in water at 25". (A) Immediately. (B) After 6 hr. (C) At completion of reaction. (Reproduced with permission from Steinberger and Westheimer J. Amer. Chem. Soc. 1951 73 439). the dimethyloxaloacetate ion and Fe3+ is bright yellow. As the decarboxylation proceeds the colour of the solution changes through green to blue; then slowly the blue fades to leave the yellow one-to-one complex of Fe3+ with the /3-methyl-a-oxobutyrate ion. Presumably the blue compound is the ferric complex of the enol of #?-methyl- a-oxobutyric acid; this assignment can be confirmed by allowing the decarboxylation to proceed in absence of metal ions until the concentration of the enol as measured by the ultraviolet spectroscopy is at a maximum; when ferric ion is then added the soIution turns blue instantly.n *-. The mechanism for the metal-ion catalysis is clear. The cation forms a chelate with the dianion of the keto-acid'~~~ and so provides a centre of positive charge at the carbonyl group. The decarboxylation requires an electronic shift from the /3-carboxylate ion group to the carbonyl-oxygen atom of the keto- acid accompanied by the cleavage of a carbon-carbon bond; the electronic shift is facilitated by a positive charge at the keto-group. 'I Steinberger and Westheimer J. Amer. Chem. SOC.,1949 71 4158; 1951 73 429. Owen J.1945,385. Krebs Biochem. J. 1943.,36 303. loGraham Dissertation University of Chicago 1953. FIG.2. The ciltracentr$ugal pattern for the crystalline enzyme Jiom ATCC 862. FIG.3. Stasch-gc[ ckec.trop~1orc.si.sof the enzyme nt its isoekectric point at higher pH and at hwcr QH. FIG.4. The crystalline enzyme from ATCC 862 under 750 magni3cations. SEPTEMBER The decarboxylation of acetoacetic acid is not catalysed by multivalent cations but a proton could in principle supply the needed positive charge. Pedersen suggested that a minute concentration of a zwitterion is in equilibrium with acetoacetic acid and the intermediate then undergoes decarboxylation to the enol of acetone? CH3.C-CH,*C02H CH,C.CH,*CO2-ll I/ 0 +OH J.CH,-C=CH, I OH Further investigationll suggested that this mechanism requires some modification since the decarboxyla- tion proceeds at the same rate in solvents of low as in solvents of high dielectric constant. Since the rate is insensitive to the polarity of the solvent the transi- tion state must more nearly resemble a &membered hydrogen-bonded intermediatell than a zwitterion. Although reaction kinetics cannot determine whether or not such a transition state is formed via a zwit- terion as intermediate1 (in fact the question is meaningless) the results do demonstrate that the separation of charge in the transition state is minimal and they suggest that the rate of decarboxyl- ation is less than that which would obtain were a full positive charge placed on the oxygen atom of the carbonyl group.The decarboxylation of acetoacetic acid is strongly catalysed by primary amines; biochemists have long used aniline citrate to promote the decarboxylation of /3-keto-acids. On the basis of his study of the decarboxylation of dimethylacetoacetate catalysed by o-chloroaniline Pedersen12 suggested that the pro- cess takes place according to the scheme annexed via a SchB base as intermediate. Such a Schiff base could readily be protonated to a zwitterion which in turn may undergo decarboxylation to form an enamine. The reaction should be favoured relative to the decarboxylation of acetoacetic acid because the nitrogen atom of the ketimine is so much more basic than the corresponding carbonyl-oxygen atom; the zwitterion (IV) should be present in solution in reasonably high concentration.After the decarboxyl- ation the enamine could be protonated to the Schiff- base salt of isopropyl methyl ketone and the Schiff- base salt could be hydrolysed to form the final pro- duct. Regrettably the kinetics of the amine-catalysed decarboxylation12 do not clearly define the mechan- ism; perhaps the formation of the Schiff base is 0 NAr II CH,-C-CMe,-CO,-+ Ar-NH + CHs4!CMe,C0,-+ H,O NAr *NHAr ll II H+ + CH,CCMe,.CO,-+ CH,-C-CMe,CO,-(IV) NHAr I (IV) + CH,.C=CMe + CO (7) H Ar ‘N’ +NHAr I 11 CH,.C=CMe + H+-F CH,.C-CHMe J. HzO CH,GCHMe + ArVNHf II 6 rate-limiting.ll However the mechanism is a reason- able one and forms the basis of the suggestion here advanced for understanding the enzymic decar- boxylation of acetoacetic acid.The Isolation Purification and Properties of the Enzyme.-”he enzyme which catalyses the decar- boxylation of acetoacetic acid to acetone is isolated from Clostridium acetobutylicurn ;lS for many years the commercial production of acetone depended upon a fermentation process which utilised these bacteria. Our purification procedure for the enzyme is based on the earlier researches of R. Daviesl3*l4at Cambridge. The bacteria are converted into an acetone powder which is extracted with a 0.02~-phosphate buffer at pH 5.4. Then the enzyme is precipitated from the extract by acetic acid at pH 3.9.’ The enzyme is redissolved in phosphate buffer at pH 5.9 reprecipitated at pH 3.9 and subsequently chromatographed.When the chromatography is carried out over hydroxyapetite about 75% of the activity present in the original extract can be re covered in an enzyme purified about 2Wfold over the original acetone powder. The purest material however requires further chromatography over di- ethylaminoethylcellulose a procedure which entails some loss of yield but leads to enzyme which can be crystallised16J6 and which has 2-3 times the activity of the best material previously14 reported. The purity of the crystalline enzyme with respect to ultracentri- l1 Westheher and Jones J. Amer. Chem. SOC.,1941,63 3283. Pedersen J. Phys. Chem. 1934,38,559; J.Amer. Chem. SOC.,1938,60,595. l3 Seeley in “Methods in Enzymology,” eds. Colowick and Kaplan Academic Press,Inc. New York 1955 Vol. I p. 624. l4 Davies Biochem. J. 1942,36 582; 1943,3? 230. lS Hamilton and Westheimer J. Amer. Chem. SOC. 1959 81 2277. Zerner unpublished work. fugation is shown in Fig. 2; the purity with respect to starch-gel electrophoresis is shown in Fig. 3. Apparently the enzyme is monodisperse and travels on both sides of its isoelectric point as a single band with little trailing. The crystals are shown under 750 x magnification in Fig. 4. Although the procedure for isolating the enzyme is straightforward and although the enzyme is stable even at room temperature the problems connected with its isolation have caused us considerable diffi- culty.The first crystallisation of the enzyme15 was accomplished from Clostridiurn acetobutylicum, strain 862 of the American Type Culture Collection. This strain has unfortunately been lost and is no longer available. Much of the work here reported has been carried out with NRRL-B-528 obtained from the U.S. Department of Agriculture at Peoria; this strain is similar to ATCC 862 and yields an enzyme of comparable activity by the same purification pro- cedure. The new enzyme crystallises in two modifica- tions:16 hexagonal plates microscopically similar to those shown in Fig. 4 and in short needles. A further investigation has been conducted with Ciustridium madisonii." These bacteria make an enzyme of com- parable activity to that from NRRL-B-528 but now the enzyme is extracted from the acetone powder at a different pH and has a different isoelectric point Werent chromatographic properties and a some- what different Svedberg number.17 The individuality of the two catalysts has been emphasised by an ex- periment in which purified enzyme from CZ.madisonii has been mixed with that from NRRL-B-528.The two proteins were readily separated by chromato- graphy over diethylaminoethylcellulose,or by starch- gel electrophoresis at a pH intermediate between their isoelectric p0ints.l' To date some of the mechanistic studies have been carried out with one strain and some with another. The arguments below are based on the assumption that the fundamental mechanism of decarboxylation is the same for all three enzymes although of course some minor details must necessarily be changed for proteins with physical properties which differ as do those described above.The reaction kinetics have been investigated in a prelimiwry fashion for the enzyme from CZ. madisonii. Fig. 5 shows the plot of the logarithm of Vmx,against pH and Fig. 6 the plot of Vmu,/KM against pH. Both these pH-rate profiles exhibit typical bell-shaped curves and can be correlated on the basis of two pK's in the neighbourhood of 5.5 and 6.5. (The exact values are 5.55 and 6.67 for the PROCEEDINGS +0*2r - -o"'* ~*3~,-I ~ 5.4 5.8 6-2 6.6 7.0 PH FIG. 5. Plot of V,,,. against pH for the enzyme from C1.madisonii. Full line -theoretical curve for pKar 5.55 and pKbps = 6.67 21p PH FIG. 6. Plot of Vmm.lKMagainst pH for the enzyme from Cl.madisonii. Full line = theoretical curve for pKaE= 5.38and pKbe =6.36. curve for Vma, and 5.38 and 6.36 for that for Vmax./KM.)In the least complicated and most straightforward interpretation of enzyme kinetics,fs these pK's should correspond to the ionisations of two groups in the enzyme-substrate complex and in the enzyme respectively which are involved in enzymic activity. The identification of these pK's as ionisable groups in the enzyme requires some ex- planation since none of the typical side-chains of the natural amino-acids shows a pK near 5.5. In order to decide or at least attempt to decide the charge type of the ionisations the kinetics were repeated in 30% alcohol,17 as a result of the suggestion made for ribonuclease by Rabin and his collaborators.fs Fig.7 shows how the curve for V,,,. against pH is shifted * The authors are indebted to Professor H. W. Seeley for a gift of spores of strain 16. R. Colman Thesis RadclXe College 1962. laAlberty Adv. Enzymology 1956,17 1. Is Findlay Herries Mathias Rabin and Rose Nature 1961 190 781. SEPTEMBER 1963 257 slightly to lower pH values in the mixed solvent. Control experiments demonstrated that this small shift in pK to lower values in 30% ethanol is typical of acids such as imidazolium ion of the type BH+. By contrast electrically neutral acids such as acetic of the type HA show pK values in 30% ethanol which are 0.3-0.4 pK unit greater than those in water.The divergence in behaviour is that expected; the work of ionisation of an acid of the type HA to form two oppositely charged ions is increased in a solvent of a lower dielectric constant whereas the work of ionisation of BH+ to form an ion and a neutral molecule is to a first approximation un- changed by a decrease in the dielectric constant of the medium. Again on the assumption of the simplest and most straightforward reaction kinetics these results indicate that the ionisations pertinent to the enzymic decarboxylation are those of acids of the BH-type (e.g. Schiff-base salts etc.). However +0.2r-x P conclusions such as these drawn from kinetics must be accepted with considerable reservation since the apparent pK's derived from pH-rate profiles need not correspond to those of any of the ordinary groups of protein side chains;20 in fact with com- plex mechanisms the apparent pK's may be widely displaced from those of the groups which are actually undergoing ionisation.21 Before the mechanism of action of the enzyme is considered one more piece of information should be presented.The enzyme (or rather the enzymes) can be strongly inhibited by univalent anions;22 for example both bisulphite and cyanate cause 50% in-hibition at about ~O-*M. The series of inhibitors nearly parallels the Hofmeister series in reverse; anions such as sulphate ion which generally pre- cipitate proteins are without inhibitory effect where- as anions such as nitrate and perchlorate which usually have no effect upon proteins are strong inhibitors for the decarboxylase (Table 1).Of course the kinetics here described were carried out with non-inhibitory anions in the buffer solutions. The effect of anions suggests that a cationic site is essential to enzymic activity and thus strengthens the conclusion from the kinetics in 30 %ethanol. Further the inhibition by anions is ineffective at high pH. The pK for the postulated cationic site for the enzyme from NRRL-B-528 deduced from the pH behaviour of anionic inhibition is 5.8; this value is near that of the pK's determined by a consideration of the overall kinetics and suggests that one of the ionisation con- stants may really correspond to that of an ammonium salt group.The details of the inhibition by anions have been considered elsewhere.23 The Mechanism of the Enzymic Process.-At the beginning of this Lecture it was suggested that the mechanism of enzymic decarboxylation of aceto-acetic acid requires the formation of a Schiff base as \ and irz wafer. an intermediate followed by decarboxylatiot of this Schiff base. This hypothesis was suggested n 958 TABLE 1. Anion inhibition pH 5.2 and 30". Anion Concn. (10-5~) for 50 7i inhibition HS0,-7 SCN-11 c10,-73 I-100 NO3-126 C103-400 Br-1000 c1-5000 Br03-7600 F-10,Ooo 10,-10,Ooo Cl,C-CO,-33,000 2o BNlice and Sturtevant J.Amer. Chem. SOC.,1959,81,2860. Zerner and Bender J. Amer. Chem. SOC.,1961 83,2267. 32 Fridovich J. Biol. Chem. 1963 238 592. 23 Hamilton and Westheimer J. Amer. Chem. Soc. 1959 81 6332. 258 PROCEEDINGS on the basis of the experiments performed by Gordon and that the exchange of the oxygen atom in aceto- Hamilt0n,2~ who carried out the enzymic decar- acetic acid accompanies the decarboxylation process. boxylation of acetoacetic acid labelled in the These experiments suggest23 that the decarboxylation ketonic-carbonyl group with lSO. If the Schiff-base may proceed by way of a Schiff base as intermediate. mechanism is correct then the exchange of the 2. ketonic-oxygen atom with the solvent is obligatory; TABLE if the decarboxylation follows the usual pathway for Oxygen exchange in the enzymic decarboxylation non-enzymic decarboxylation of /3-keto-acids the of acetoacetic acid.carbonyl-oxygen atom would be retained in the Control Decarboxn. product (reaction 1). The results however are Acetone meaningful only if accompanied by careful control Alone 15 40 experiments. Both acetone and acetoacetic acid can + 0.45 mg. enzyme 57 undergo non-enzymic exchange of the carbonyl + 0.90 mg. enzyme oxygen atom with water (reactions 2); although the Acetoacetate exchange between acetone and pure water is Alone 25 the process is strongly catalysed by acids.24 + 0.45 mg. enzyme 45 98-5 + 0-90mg. enzyme 61 100.0 H20 CH,.CO **CHz.C02H -+ CH3*C0 *.CH Additional evidence has been secured from boro- or 13-co2 * (1) hydride reductions modelled on the method CH,*CO*CH J originated by Edmond Fischer and his collaborator^^^ CH3*C0 *.CH + H20 + CH,-CO*CH + H,O * 7 at the University of Washington in Seattle to study CH3.C0 *-CHz*COz- + HzO + CH3*COCHzCOz-I...the chemistry of phosphorylase-a. This enzyme + H,O* (2) requires pyridoxal phosphate as a coen~yme.~~~~~ In Some of Hamilton’s results and some of his con- slightly acid solutions phosphorylase-a is yellow trol experiments are shown in Table 2. The decar- suggesting that the aldehyde group is bound to the boxylations were carried out under a slight vacuum in a vessel attached to a distilling column; as acetone was formed it was volatilised from the reaction mix- ture fractionated from water and condensed in a cold trap.The acetone from the cold trap was re- distilled and examined for l80mass-spectrometrical-ly. In the control experiments acetone was allowed to stand in the reaction mixture for the time normally required for decarboxylation before it was distilled into the cold trap and subjected to isotopic analysis. The control experiments for exchange of oxygen between the solvent and acetoacetate were conducted by allowing partial decarboxylation and then freezing the reaction mixture to stop both decarboxylation and exchange of isotopic oxygen. The frozen solution was lyophilised to dryness and the residual aceto- acetate decarboxylated by heating it with phenol. Thus the control experiments allowed a greater opportunity for non-enzymic exchange than the de- carboxylations themselves and the percent of exchange recorded in Table 2 represents an upper limit to that which may have accompanied the enzymic experiments.Although the non-enzymic exchange cannot be neglected the experiments demonstrate that the exchange of the carbonyl- oxygen atom of acetone is catalysed by the enzyme IY 24 Cohn and Urey J. Amer. Chem. SOC.,1938 60 679. 2’ Fischer Kent Snyder and Krebs J. Amer. Chem. SOC.,1958 80 2096. 26 Cohn in “The Enzymes,” eds. Boyer Lardy Myrback Vol. V 2nd edn. Academic Press Inc. New York 1961 D.179. 27 Braunstein in “The Enzymes,” eds. Boyer Lardy and Myrback Vol. 11 2nd edn. Academic Press Tnc. New York 1960 p. 113. SEPTEMBER protein as an azomethine.When Fischer and his col-laborators subjected the enzyme at pH 4.5 to reduc-tion with sodium borohydride it was decolorised but not inactivated. Pyridoxal phosphate could no longer be separated from the enzyme by dialysis but complete hydrolysis of the reduced protein led to the isolation of c-pyridoxyl-lysine. Thus borohydride reduced the Schiff base formed from pyridoxal and the enzyme without damaging the protein. With this work as m~del,~~-~O an attempt was made to reduce the Schiff base which had been postulated23 as an intermediate in the decarboxyla- tion. The reduction with borohydride was partially successful31 as can be seen from the results in Table 3. Borohydride alone has relatively little effect upon TABLE 3.Borohydride reduction of acetoacetate decarboxylase Compounds added to enzyme Activity (%) after dialysis 0.025M-acetoacet a t e 100 O.025M-BH4-90 i5 0.025~-acetoacetateC 0.025~-BH,-28 2.5 Y 10-4M-HCN 86 O.O25~-acetoacetate+ 0.025~-B).I~-+ 2.5 X 10-4M-HCN 69 the activity of the enzyme but in the presence of substrate the activity is sharply if incompletely diminished; repetition of the reduction progressively decreases the enzymic activity. The results correspond to the reduction of the postulated Schiff base by borohydride with concommitant interference with the active centre 5H*-RR’C = N-Enz -+ RR’CHeNH -Enz Further evidence in favour of the Schiff base arises from the inhibition of the enzyme by hydrogen cyanide.31 The rates of enzymic decarboxylation of acetoacetate at pH 7 in the presence and in the absence of 3 x 10 %-hydrogen cyanide are shown in Fig.8. The concentration of cyanide is much lower than that at which anionic inhibition occurs even with the most efficient anions; besides this acid inhibits more strongly at pH 6 than at 7 and even at pH 7 less than 1 % of it is present as cyanide ion. The striking feature of the curve is the induction period of a minute or two before inhibition is noticeable. The induction period cannot be elimin- ated by preincubating the hydrogen cyanide with either the enzyme or with the substrate. Therefore the cyanide presumably reacts with some inter-mediate formed between the protein and aceto-acetate rather than with either component alone.Time (sec.) FIG. 8. The induction period in setting up the inhibition by hydrogen cyanide for the enzyme from NRRL-B-528 at 25”. (A) No cyanide. (B) 2-7 x 1O-6M-cymide. This needed intermediate is presumably the Schiff base; the reversible addition of hydrogen cyanide to aldimines and ketimines is well and forms the basis for the Strecker synthesisw of amino- acids. Furthermore consistent with the reversible addition of hydrogen cyanide to the Schiff base its inhibitory efFects can be eliminated by prolonged dialysis. CN I RR’C = N -Enz + HCN + RR’C-NH -Enz . .(3) Now if equation (3) represents the reaction between cyanide and the Schiff base then hydrogen cyanide should protect the enzyme against reduction by borohydride.The results of one such experiment appear in Table 3. Although complete recovery of enzymic activity was not attained with dialysed enzyme after inhibition with cyanide and although protection of the enzyme against reduction was in- complete the results demonstrate that hydrogen cyanide partially protects the enzyme against reduc- 28 Cf. Dempsey and Christensen J. Biol. Chem. 1962 237 1113. 29 Grazi Cheng and Horecker (Biochem. Biophys. Res. Comni. 1962 7 250) have carried out similar researches with aldolase. 30 Horecker Pontremoli Ricci and Cheng (Proc. Nat. Acad. Sci. U.S.A. 1961 47 1949) have carried out similar researches with transaldolase. 31 Fridovich and Westheimer J. Amer. Chem. SOC.,1962,84,3208.More recent experiments show that results similar to those shown in Table 3 are obtained only with more dilute solutions of borohydride. 33 Miller and Plochl Ber. 1892 25 2020. 33 Cocker and Lapworth J. 1931 1391. 3* Adams and Taylor Org. Synth. Coll. Vol. I 1941 p. 347. tion by borohydride. These experiments confirm the hypothesis that both hydrogen cyanide and boro- hydride attack the enzyme at the same site and support the idea that this site is a Schiff base. The most compelling experiments consist in carry- ing out the reduction with acetoacetate labelled in the 3-position with 14C. When the enzyme was treated with radioactive acetoacetate and boro-hydride radioactivity was irreversibly incorporated into the protein.31 After extensive dialysis the incor- poration of radiocarbon corresponded to one atom of 14Cfor each 50,000 molecular-weight units in the protein.(In the absence of borohydride the radio- activity could be almost completely removed by dialysis; see Table 4.) The labelled protein was com- pletely hydrolysed with G~-hydrochloric acid at 1 lo” TABLE 4. Borolzydride reduction of the enzyme in tlze presence of 14C-Eabelled acetoacetate. Disintegrations Enzyme + labelled acetoacetate per min. per mg. 1700 Enzyme + labelled acetoacetate + BH4-22,000 and the resulting mixture of amino-acids was sub- jected to two-dimensional paper chromatography. A radioautograph of the chromatogram showed that all the radioactivity is concentrated in a single com- pound.The radioactivity from that spot has been eluted and examined by electrophoresis and by paper chromatography in three separate solvent systems. The labelled compound has been tentatively identifiedl8* as E-isopropyl-lysine by a comparison in three solvent systems of its RF)s with those of a synthetic sample of the alkylated amino-acid. Thus under the experimental conditions of these experi- ments acetoacetate was decarboxylated before reduction. Summary.-The results here presented demon- strate that a Schif€ base is formed between aceto- acetate or acetone and the eamino-group of a lysine residue in the enzyme and that this lysine residue must be at or near the active site since alkylation severely diminishes enzymic activity.However it goes almost without saying that the results do not prove that a Schiff base is actually an intermediate in the decarboxylation; it could be merely a non- essential product of a side-reaction which occurs between substrate and an amino-group that is near the active site. The incomplete inactivation of the enzyme on reduction by borohydride in the presence PROCEEDINGS of substrate even hints that such is the case. Never- theless the hypothesis of a Schiff base as inter- mediate has led to the discovery of many new facts about the enzyme and it correlates and explains these findings. The formation of a Schiff base between substrate and enzyme is suggested by the exchange of the carbonyl-oxygen atom that accompanies enzymic activity.Subsequent decarboxylation of a zwit-terionic Schiff base to an enamine would parallel the mechanism which Pedersen postulated for the non- enzymic process; moreover it parallels one of the established steps in the pyridoxal-catalysed decar- boxylation of amino-acid~.~~,~~ The hypothesis has been strengthened by the inhibition of the enzyme by hydrogen cyanide and by the induction period neces- sary to establish this inhibition. And the formation of a Schiff base from the product and a lysine residue on the enzyme is supported by the results on boro- hydride reduction in the presence of [3-14C]aceto- acetate. Furthermore the scheme here shown is consistent with the kinetics. An analysis of the postulated reaction sequence requires nine parameters five rate constants and four ionisation constants.The result- ing rate equations are quite complicated but they predict a bell-shaped pH-rate profile both for Ymax. and for Vmax./KM.The four apparent pK’s which arise from the kinetic treatment do not correspond to the pK’s of any simple ionising group; the ionisation constants are modified by multiplication by rate-constant ratios in the manner which Zerner and Bender previously21 outlined for enzyme kinetics in general. However at this rather early stage in the analysis of the reaction kinetics many alternative schemes must be considered. Although the work here described suggests a possible pathway for the enzymic decarboxylation of acetoacetate the postulated mechanism must be treated with caution.In common with the other proposals for the action of the evidence is incomplete and the mechanism is far from attain- ing that degree of probability which obtains for the mechanisms of non-enzymic reactions in organic chemistry. Further even if the pathway here sug- gested should eventually prove to be correct the details of enzyme action have not yet been elucidated. For example the mechanism so far described does not account for the observed14 inhibition of the decarboxylase by mercuric chloride. Again the rate of the enzymic process is much greater than that for the corresponding model systems. It need scarcely be emphasised that a complete understanding of the mechanism demands an explanation of this rapid * The chromatography was carried out after presentation of this Lecture in London.35 Mandeles Koppleman and Hanke J. Biol. Chem. 1954 209 327. 36 See for example “Enzyme Models and Enzyme Structure,” 15th Brookhaven Symposium in Biology June 1962. SEPTEMBER 1963 rate. In any event a method has been developed for the preparation of a pure enzyme and the way is open to perform chemical experiments with substrate quantities of this protein; hopefully these experi- ments can lead to a firm understanding of the mechanisms of the enzymic decarboxylation. Finally it is my pleasure to acknowledge the contributions of the skilled investigators at the Uni- versity of Chicago and at Harvard who contributed so much to this problem.These include Drs. Roberta 26 1 Colman Irwin Fridovich Roger Graham Gordon Hamilton William A. Jones Robert Purdy Stanley Seltzer Rudy Steinberger and Burt Zerner. Particu- lar mention must be made of Dr. Steinberger who carried out the experiments with dimethyloxalo- acetic acid of Dr. Gordon Hamilton who first crystallised the enzyme from CI. Acetobutylicum and carried out the oxygen-exchange experiments and Professor Irwin Fridovich who accomplished the borohydride reduction. THE 1962 CHEMICAL SOCIETY LECTURES IN AUSTRALIA THEChemical Society with the collaboration of the Royal Australian Chemical Institute sponsors an annual lecture tour by an Australian chemist of the major centres of chemical activity in Australia.The lecturer for 1962 was Professor R. H. Stokes of the Department of Physical and Inorganic Chem- istry of the University of New England Armidale N.S.W. The tour was split into two parts the first part (July 11-25th) involving visits to Canberra Melbourne Hobart Launceston Adelaide and Perth and the second part (September 24-29th) covering the centres nearer to Armidale viz. Sydney Newcastle and Brisbane. The lecturer expresses his thanks to the Chemical Society and the R.A.C.I. for the opportunity to make this tour and to his hosts in the various centres for the hospitality extended to him. Lecture I was given in all the centres and most of the centres also heard Lecture I1 or Lecture 111. A summary of the contents of these lectures follows.I. pH Relations in Acid-Base Systems The calculation of pH in solutions of weak acids or bases at various degrees of stoicheiometric neutralisation with strong base or strong acid is usually dealt with at the elementary level by various approximation methods valid under particular con- ditions. For example if the pH is less than 5 the hydroxide ion concentration may be neglected rela- tibe to the hydrogen ion concentration; if the con- centrations of both the acid and conjugate base forms are high relative to hydrogen ion or hydroxide ion Henderson’s equation applies etc. The student often has difficulty in deciding when to use a particu- lar approximation. Another aspect of pH calcula- tions of increasing importance as the use of auto- matic titrators increases is the location of points of inflexion in pH titration curves and this part of the theory is best handled by completely general equa- tions not restricted to particular ranges of pH or other variables.The reason why the most general equations are seldom used is that even for a mono- basic weak acid the expression for the stoicheio- metric degree of neutralisation is a cubic in the hydrogen ion concentration and the expression giving points of inflexion is a quintic in the hydrogen ion concentration; while for a dibasic weak acid the corresponding expressions are a quintic and a seventh-degree equation. The lecture showed how these equations can be cast into forms suitable for immediate and effortless graphical solutions.Use is made of dimensionless quantities such as X = In [Hf]/dKw and the equations are expressed in terms of hyperbolic functions. For monobasic weak acids (or the conjugate bases) in any solvent at any temperature only two permanent graphs are needed. One of these is transparent and is superposed on the other with shifts of the origin in the horizontal direction to suit the pKa value of the weak acid-base system and in the vertical direction to suit its con- centration. The pH values at zero one-half and complete stoicheiometric neutralisation can then be read directly from relevant points of intersection of the two graphs and the pH values at inflexion points in the titration curve are similarly exhibited. The fact that the titration curve may have one or three inflexions is clearly shown and the existence of the critical concentration C = 27K (or C = 27Kw/Ka) for transition between these two cases is readily shown.For dibasic acids a separate transparent graph is needed for each different value of pK -pK, and the possibilities of one three or five inflexions are apparent. A detailed account of the procedure is in course of publication elsewhere. 11. High-precision Conductance Measurements on Electrolytes In a laboratory equipped for high-precision con- ductance measurements many routine analytical measurements can be done with great precision and speed. An accuracy of 0-01 % in the analysis of pure solutions of acids and salts can be attained without undue effort.The conductance of hydrochloric acid solutions is a particularly convenient standard for acidimetric work and the methods by which the conductances have been measured was described in detail. The composition of the primary hydrochloric acid stock solution may itself be determined con- ductimetrically by weight-titration with unknown (but carbonate-free) sodium hydroxide followed by measurement of the conductance of the sodium chloride solution formed. Thus the real primary acidimetric standard becomes the conductance of sodium chloride solutions which is known with a precision of i0405% over the relevant range of concentration. After a conductance measurement on a solution of unknown concentration the concentra- tion is computed by a rapidly-convergent series of successive approximations using graphs of suitable deviation functions of the equivalent conductance which can be read with the necessary accuracy.Stock solutions of salts for which really accurate gravimetric analysis might be very time-consuming can readily be prepared by conductimetric analysis of the appropriate acid followed by stoicheiometric neutralisation with the base to give a known final weight of salt solution. The precautions necessary in high-precision con- ductance work were reviewed; in addition to the old-established ones errors due to thermal diffusion PROCEEDINGS during the warming-period after placing the cell in the thermostat may arise in certain designs of cell and it is desirable to use a cell in which the contents may be thoroughly mixed after temperature equi- librium has been reached.Special methods necessary in work on sodium hydroxide solutions were discussed. III. Activity Measurements in Three-component Solutions This lecture directed primarily to specialists in solution thermodynamics was concerned with methods of determining activity coefficients in three- component solutions. In most cases the activity of only one component is experimentally accessible e.g. the solvent vapour pressure may be measured or the e.m.f. of a cell may give the activity of one solute. To obtain the other activities use is made of the cross-differentiation relationship and of the Gibbs-Duhen relationship .&idpi = 0 (p = chemical potential).The cases discussed included solubility measure- ments isoprestic vapour pressure measurements and electromotive force measurements. COMMUNICATIONS Evidence for Geometric Isomers of the Chlorotetraethylenepntaminecobalt(In)Ion By R. T. M. FRASER (DEPARTMENT THE UNIVERSITY LAWRENCE U.S.A.) OF CHEMISTRY OF KANSAS KANSAS IN a report1 of the preparation of solid nitrito- tetraethylenepentaminecobalt(m) perchlor ate [{ NH,,(CH,.CH,*NH),.CH,.CH2.NH2 1Co(N0,) ] (ClO,) the possibility was discussed of obtaining the four geometric isomers (I-IV; X = NO,). Three of these are potentially optically active but attempts to resolve the mixture were unsuccessful. The rate of aquation of the related complex ion (tetrenCoCl),+ (where tetren = tetraethylenepentamine) has been studied and the form of the rate plot led the in- vestigators to believe that their compound was impure.This ion (tetrenCoCl),+ has also been made by the same method but from purified tetraethyl- enepentamine? and evidence has now been obtained for both geometric and optical isomers by utilising an electron- transfer reaction. Reduction of chlorotetraethylenepentaminecobalt-(III) perchlorate with chromium(II) or vanadium(I1) in aqueous perchloric acid yields a rate plot showing two components to be present. For each component the rate of reduction is of the second order (of first order in both complex and reductant) and is not catalysed by hydrogen ion. Table 1 lists some rate constants for the vanadium(I1) reductions.Examina- tion of the rate plots for different batches shows that 4651% of the complex is present as the “fast” species. Molecular models of the complexes (1-IV; X = C1) indicate that for steric reasons (I) and (111) will be more difficult to form than (IT) and (TV). Table 2 lists entropies and enthalpies of activation for the reductions together with the free energies of activa- Selbin J. Inorg. Nuclear Chem. 1961 17,84. Pearson Boston and Basolo J.Phys. Chern. 1955,59 304. Jonassen Frey and Schaafsma J. Phys. Chem. 1957 61 504. SEPTEMBER 1963 263 tion of the tetren complexes and of cis- and trans- chloroamminebisethylenediaminecobalt(nI) and shows that the free energies for the “slow” form of the tetren complex and of cis-en2NH3CoC12+ (V) are very similar as are those for the “fast” tetren com- plex and trans-en2NH3CoC12+.This is interesting since the shape of the latter is very much like that of isomer (11; X = Cl) at least when viewed from the side of the chloride ligand. X X The ratio of rate constants for the reduction of the tetren complexes at 21” is 6.3. Accordingly a series of experiments were made in which 7.8 equivalents of the tetren mixture were dissolved in the smallest volume of M-perchloric acid sufficient to protonate the products of the reaction and 4.5 equivalents of vanadium(@ perchlorate were added. If the two components ofthe mixture are two geometric isomers reacting at different rates this procedure will remove all the “fast” (but only about 0-6equivalent of the “slow” isomer) through the reaction C,H2,N,CoCI2+ + Vz+ + 5H+ 3 C,H2,N,5+ + Co2+ + v3+ + ci-After 10 minutes the reaction mixtures were poured through a column of Dowex 1 ion-exchange resin in the chloride form (to remove perchlorate ion) and treated with a slight excess of silver (+)-camphorsulphonate.The silver chloride was filtered off and the solution concentrated under reduced pressure in the presence of concentrated sulphuric acid and sodium hydroxide pellets. The first crop of crystals were separated washed with ether then redissolved in a small volume of water and poured through a second column of Dowex 1 in the chloride form to remove (+)-camphorsulphonate Werner Ber.191 1,44 1887. and silver (as silver chloride). The eluate was examined for optical activity Table 3 shows some results. The rotation observed is in the expected direction4 and is not due to traces of (+)-camphor- sulphonate ion since it decreases with time as aquation of the chlorotetraethylenepentaminecom-plex occurs. The low specific rotation probably arises from incomplete resolution due to the high solubility of the cobalt(m) camphorsulphonates and the presence of some vanadyl (V02+) and ammonium ions in the eluates. TABLE 1. Rate constants for reduction of cobalt(m) complexes by vanadium(n) (p = 1.0). Complex k (I. mole-l sec.-l) Temp. tetrenCoC12+ “fast” 5.4 21.0” 3.3 10.0 ‘slow’’ 0.85 21.0 0.44 10.0 cis-en ,NH3CoC12+ 1-25 29-0 0.68 19.0 0.40 10.0 TABLE 2.Activation parameters for reductions by vanadium(n) at 21”. Complex AH+ (kcal.1 mole-l) tetrenCoC12+ AS* (e.u.) AG* (kcal.1 mole-l) “fast” 7.3 -301 16.3 “slow” 9.3 -27 17.4 cis-en2NH,CoC12+ 9.1 -28 17.5 trans-en2NH3CoC12+ - - 16.1 TABLE 3. Optical rotations of eluates. Sample [Co(n1)L2+]* % bI2l 1 1.88 x 10-3~ 0.15 22 4 2.20 x 10-3M 0.20 25 * Molecular weight of the complex = 362. The author acknowledges his indebtedness to the National Science Foundation for support of this work. (Received June 24th 1963.) PROCEEDINGS N-Stannylcarbamates and their Role as Possible Intermediates in the Formation of Urethanes By A.J. BLOODWORTH G. DAVIES and ALWYN RAMSAY LABORATORIES COLLEGE W.C. 1) (WILLIAM AND RALPHFORSTER UNIVERSITY LONDON WE have found that tin(rv) alkoxides react readily with organic isocyanates to give a new family of very reactive organotin compounds the N-stannyl-carbamates. For example tributylmethoxytin and 1-naphthyl isocyanate at room temperature rapidly and exothermically give methyl N-tributylstannyl- N-1-naphthylcarbamate(I) in essentially quantitative yield (Found C 58.8;H 7.9; N 3.0; C,4H3702Sn requires C 584; H 7-6; N 2.8%). Bu,Sn-OMe l-Cl,H,.NCO 4 Bu,Sn.N(l-C,,H,)CO,Me (I) 4HA Bu,SnA + l-C1,H,.NH.CO,Me (HA = H,O H,S HOAc HOEt etc.) Protic reagents HA readily break the Sn-N bond liberating methyl N-1-naphthylcarbamate and the corresponding compound Bu,SnA ;in particular an alcohol ROH thereby regenerates a tin alkoxide Bu,Sn*OR.Characteristics of some of these N-stannyl-carbamates are Et,Sn*NBuCO,Et b.p. 57-5“j0.01 mm. ;Et,Sn~N(1-Cl0H7)~CO,Et, b.p. 108”/0.05mm. m.p. 86-93’; Bu,Sn-NPhCO,Me b.p. 99-100’/ 0.01 mm. ;Bu,Sn.NPhCS.OMe b.p. 68”/0.02 mm. ; and Bu3Sn.N( 1 -CloH7)C02Me b.p. 120”/0.01 mm. These results are relevant to the catalysis by organotin compounds of the alcohol-isocyanate reaction,* itself of importance in the commercial production of po1yurethanes.l It is now likely that the mechanism of the catalysis involves the prior formation of a tin alkoxide; this rapidly adds to the isocyanate to give an intermediate N-stannyl-carbamate which then rapidly undergoes alcoholysis to give the carbamate and regenerate the tin alkoxide.As far as we are aware such a mechanism has not been considered previously. (Received July loth 1963). * For example 10 mole O0 of dibutyltin dilaurate accelerates the formation of n-butyl N-phenylcarbamate from n-butanol and phenyl isocyanate by a factor of 600,000. (a) Farkas and Mills “Catalytic Effects in Isocyanate Reactions,” in Adv. Catal,vsis 1962 13 393. (b) Saunders and Frisch “Polyurethanes,” Part I Interscience New York 1962 gp. 161-217. (Lone-pair)-(Lone-pair) Repulsion and Molecular Configurations ;Rotational Isomerism in Methyl Vinyl Ether Carboxylic Esters and Nitrites By NOEL L. OWEN and N. SHEPPARD CHEMICAL LENSFIELD (UNIVERSITY LABORATORY ROAD CAMBRIDGE) THE vibrational spectra of alkyl vinyl ethers have been the subject of considerable comment because of a multiplicity of bands in the C=C bond-stretching region.’- This complexity has been interpreted either as an indication of the presence of more than one rotationally isomeric species or of Fermi resonance of the C=C fundamental with an overtone (such as that of the out-of-plane CH wagging vibration).We have made a detailed study of the infrared spectrum of methyl vinyl ether in the gas liquid solution and solid states. Spectral simplification on passing from the gas to one of two possible crystalline phases shows that two rotational isomers are present al- though Fermi resonance also complicates the vC= C region.From the temperature-dependence of two gas-phase bands at 1324 and 11 38 cm.-l we estimate the energy difference between the rotational isomers to be 1.5 & 0-2 kcal./mole. The rotational fine structure of several “type-C” gas-phase bands shows that the stable configuration of the molecule is cis (Ia) and not trans (Ib) as has previously been assumed2 [calculated line spacings are 0.84 (cis) and 2.83 cm.-l (trans); the observed spacings were -0.82 cm.-l]. The stable cis-configuration of methyl vinyl ether is analogous to the usual configuration of the simple esters (IIa).4We have studied in a similar fashion the infrared spectra of a considerable range of esters (R’CO-OR R’ = H; R = Me But R’ = F C1 NH, OMe; R = Me) with a view to detecting absorption bands of trans rotational isomers (116) but in no case have we been successful.In contrast it is well known that the isoelectronic alkyl nitrites often have a small energy difference between cis (TIIa) and trans configurations (IIIb) and both forms are present in comparable concentrations.j From Kirrmann Bull. Soc. chim.France. 1939 5 841; 1954 21 1338. Mikawa Bull. Chem. Soc. Japan 1956,29 110. Popov and Kagan Optics and Spectroscopy 1962 12 17. Wilmshurst J. Mol. Spectroscopy 1957 1 201. Gray Trans. Faraday Soc. 1963 59 347. SEPTEMBER 1963 265 Stable configurations and energy diflerences AE = E (trans) -E (cis) Compound Stable dE(kcal./mole) form Formic acid 0:CH-OH' cis Methyl formate 0:CH.0Me7 cis Vinyl alcohol H2C:CH*OH Methyl vinyl ether H2C:CH.0Me cis -2 >2-7 not known 1.5 f0.2 Nitrous acid 0:N*OHS trans -0-5 Methyl nitrite 0:NmOMe trans -0.6 & 0.2 Formaldoxine H2C:N.0H9 trans <-2 new measurements on the bands at 1677 (cis) and 1621 cm.-l (trans) in the spectrum of gaseous methyl nitrite we find that the trans-form is the more stable but that the energy difference is only 0.6 & 0-2 kcal./mole. The Table summarises the energy differences for the methyl compounds and for the parent com-pounds with OH replacing OMe groups. The marked variation in energy differences between cis-and trans-isomers exhibited by these compounds can be accounted for in terms of a dominant effect of (lone-pair)-(lone-pair) electron repulsions.Formulz (I) to (IV) are drawn on the assumption that for all these compounds electron delocalisation within the X=Y-0 group is likely to favour the planar cis-and trans-forms (in the case of nitrous acid there is direct experimental evidence that both forms are planafl). The formulae also in- dicate the location of the lone-pair orbitals that are in the plane of the heavy atoms through assuming sp2 hybridisation for the ether oxygen atoms. It is seen that the instability of the trans-forms of carboxylic acids and esters could be caused by '~y (lone-pair)-(lone-pair) repulsions ;that of the cis-form of formaldoxime by 'YP repulsions,* and that the small energy difference for the nitrites could be the net result of opposed oly and olP repulsions.It has been accepted that (lone-pair)-(lone-pair) repulsions are important in determining the con- formations of hydrogen peroxide and hydrazine ;lo as a result of the present work we consider that this factor may be of considerably more widespread importance in determining molecular conformations. If our hypothesis is correct it implies that a/3 and ay (lone-pair)-(lone-pair) repulsions are of mag- nitude 2 kcal./mole or greater. Undoubtedly other non-bonded interactions make some contribution to the observed energy differences as for example with methyl vinyl ether. H H / H-C P H-c\ @ H')c-0 b HmR H H / i' H-C H-C #P *N-d R %-0 4 'R (ma) (a4 One of us (N.L.O.) gratefully acknowledges a maintenance grant from the D.S.I.R.(Received May 17th 1963.) * We thank Professor E. B. Wilson jun. for pointing out the microwave work on formaldoxime and that lone-pair repulsions could be a factor in stabilising the tram-conformation. Miyazawa and Pitzer J. Chem. Phys. 1959,30 1076. Miyazawa Bull. Chem. Soc. Japan 1961,34 691. Jones Badger and Moore J. Chem. Phys. 1951 19 1599. Levhe J. Mol. Spectroscopy 1962 8 276. lo Penney and Sutherland J. Chem. Phys. 1934 2,492. PROCEEDINGS The Use of Bifunctional Catalysts in Peptide and Other Syntheses By H. c.BEYERMAN VAN DEN BRINK and W.MAASSEN (LABORATORY HOGESCHOOL, OF ORGANIC CHEMISTRY TECHNISCHE DELFT NETHERLANDS) THEformation of amides and peptides by aminolysis of esters is considerably accelerated by compounds (I) which possess both a (weakly) basic group (B) and a (weakly) acidic group (AH) mutually situated in such a manner that a cyclic transition state allowing a concerted displacement may be postulated.These catalysts seem interesting as enzyme models; they are of value in slow aminolyses e.g. of “low-energy’’ or sterically hindered esters. Another application might be in preparation of polyamides. Catalysis involving two or more different functional groups in the catalyst molecule has been reported only occasion- ally. 2-Hydroxypyridine is far more effective than pyridine plus phenol in a concerted base-acid catalysis of mutarotation .I Multifunctional participa- tion has been established for esterases; several functional groups have been suggested including the imidazole ring of histidine.2 We investigated potential catalysts in the reaction bet ween N-benzylox ycarbon ylgl ycine cyanome t h yl ester and cyclohexylamine.Triethylamine pyrrole or pyridine did not improve the yield; phenol or phenol plus pyridine and acetic acid did so only slightly. Imidazole3 exerted stronger catalysis Bifunctional compounds (I) of our type gave much better results as shown in the Table. esters of glycine L-leucine or L-phenylalanine in acetonitrile the polypeptide was precipitated after a few minutes. Extent of reaction (%) between N-benzyloxycar-bonylglycine cyanomethyl ester and cyclohexylamine in 30 min. at 20”. Catalyst In MeCN In Me,NCHO None 11 111 Succinimide 45 Pyrazole* 63 4-Bromopyrazole 73 Imidazole” 32 1-Methylimidazole-2-t hi01 44 1,2,4Triazole* 63 63 2-H ydroxypyridine t 61 66 Pyridine-2-thiol 47 8-H ydroxyquinoline 44 * 1 -Methylpyrazole 1 -methylimidazole and 1- and 4-methyl-l,2,4-triazole,each 11%.t 3- 29% and 4-hydroxypyridine 27 %. Catalysis was also observed with “low-energy’’ esters. N-Benzoylglycine methyl ester and benzyl- amine in refluxing acetonitrile (16 hr.) yielded 5 % of product; use of 4-nitropyrazole 1,2,3- or 1,2,4-tri- azole or 2-hydroxypyridine led to &55% of 0 0-0 II + HN /I R-C-OR’ + :B N AH -+ R-CI ......OR‘ -+ R-C-N < + R’OH + :B-AH (1) A; B; AH N-Benzoylglycine cyanomethyl ester and benzyl- amine in acetonitrile (16 min.at 20”) gave 20% of N-benzoylglycylbenzylamine but 80 % in the pre- sence of 1,2,3- or 1,2,4-triazole. N-Trifluoroacetyl-DL-vahecyanomethyl ester and cyclohexylamine in acetonitrile (17 hr. at 20”) gave no crystalline product but 60 % of N-trifluoroacetyl- DL-valylcyclohexylamine on use of 1,2,4-triazole. N-Benzyloxycarbonyl-DL-vahe cyanomethyl ester and cyclohexylamine in dimethylformamide (3 days) gave 19% of product but 61% on use of 1,2,4- triazole. The ester did not react with glycine amide in aqueous dimethylformamide (17 hr.) but in the presence of 1,2,4-triazole gave a satisfactory yield of N-benzyloxycarbonyl-DL-valylglycineamide. On addition of 1,2,4-triazole to the p-nitrophenyl N-benzoylglycylbenzylamine.Imidazole gave no real improvement (7 %).The favourable effect of the former catalysts in contrast to that of imidazole not only sustains our interpretation of nucleophilic-electrophilic catalysis,” but also indicates a concerted displacement. The proton available at the correct position now allows the displacement of even a “bad” (non-acidic) leaving group such as methoxyl. An alternative possibility is a concerted displacement by general base-general acid cataly~is.~ We thank Mrs. G.A. Kuivenhoven-Noordam and Miss A. Tennekes for technical assistance Dr. S. G. Waley Oxford for reading the manuscript and N. V. Organon Oss for gifts of chemicals. (Received June 8th 1963.) Swain and Brown. J. Amer. Chem. SOC..1952. 74. 2538.Bergmann Adv. Catalysis 1958 10 130. , Bender Chem. Rev. 1960 60 77-79; Barnard and Stein Ad!. Emymol. 1958 20 51. Bender Chem. Rev. 1960,60 103-105; see also ref. 1. SEPTEMBER 1963 267 Studies of Bomes. Part VIII. Hexaborane-12 B6H,a By DONALD F. GAINESand RILEYSCHAEFFER OF CHXMISTRY UNIVERSITY INDIANA, (DEPARTMENT INDIANA BLOOMINGTON U.S.A.) WE report here that decomposition of tetramethyl-ammonium triborohydride-8 with polyphosphoric acid produces small yields of hexaborane-12 which have been separated and identified by high-vacuum techniques. The formula of the hydride is established by determination of the molecular weight by vapour density (Found 76.6. B,H12 requires 77.0) and by pyrolysis to hydrogen and boron which were deter- mined (boron by titration with base in the presence of D-mannitol) (Found B 84.2; H 15.7.B,H12 requires B 84.3; H 15.7 %). The new hydride slowly decomposes at room temperature making determination of vapour pres- sures unreliable at higher temperatures; at 0” the vapour tension is 17 mm. Decomposition produces a mixture of boron hydrides and hydrogen and is accelerated by the presence of water or dimethyl ether. We thank the National Science Foundation for support of this work. (Received July 12th 1963.) Part VIZ J. Amer. Chem. SQC.,1963 85 2020. The title of the series has been changed to describe more general studies. The Origin of the “Berberine Carbon” By D. H. R. BARTON, R. H. HESSE,and G. W. KIRBY (IMPERIAL LONDON,S.W.7) COLLEGE IT has recently been suggested1 that the so-called “berberine carbon”2 is in fact a cyclised N-methyl group.We now report the first definitive evidence that this idea is ~orrect.~ ( &)-Reticdine(I),labelled with 14Cin its N-methyl group was fed to young Hydrastis canadensis plants. The derived berberine (111) (0.7 % incorporation) was converted into the base 071) chromic acid oxidation of which gave benzoic acid containing all (106%) of the radioactivity. Similarly the precursor (I) labelled both in a methoxyl group as indicated (5.9% of total activity) and in its N-methyl group (94.1 % of total activity) gave doubly labelled berberine (0.9% incorporation). Hydrolysis with sulphuric acid gave radioactive formaldehyde (5.7 %).Deg-radation as above gave benzoic acid (91%). Clearly Barton and Kirby Summer School in Biogenesis Milan Italy Sept. 1962 in the press; Battersby Tilden Lecture Proc. Chern. Soc. 1963 189; Barton Hugo Miiller Lecture Proc. Chem. Soc. in the press. We are glad to acknowledge the independent conception of this idea by Professor A. R. Battersby. Sir Robert Robinson “The Structural Relations of Natural Products,” Oxford Univ. Press London 1955. We thank Dr. F. E. King F.R.S. for kindly drawing our attention to a chemical analogy; see King and Clark-Lewis J. 1951 3080. Freund and Beck Ber. 1904,37 4673. PROCEEDINGS neither extensive demethylation nor fragmentation of the precursor takes place during biosynthesis and the “berberine carbon” is derived from an N-methyl group presumably by cyclisationl of the iminium ion (11) or by an equivalent radical process.In a parallel experiment5 3-( 3,4-dihydroxyphenyl) [2J4C]- alanine was incorporated into berberine (0.9 %). Our experiments also constitute the second example of the oxidative cyclisation of an o-methoxyphenol to a methylenedioxy-group.6 It is of interest that the hydrastine obtained together with berberine was essentially inactive. [N-Methyl-14C]-(f)-Reticuline also served as a precursor for protopine (IV) (1 -0% incorporation; cf. [2J4C]tyrosine incorporation 2.3 %) in Dicentra spectabilis. As expected there was no radioactivity (< 2 %) in the N-methyl group of the protopine (IV). Reduction of the methos~lphate~ gave the Emde base (V) m.p.111-112”. Chromic acid oxidation gave acetic acid which was degraded by the Schmidt procedurea to methylamine having all (96%) the activity of the original protopine (V). Reticuline appears to be of general importance in the biosynthesis of alka1oids.l The hypothesis that the “berberine carbon” of indole alkaloids represents a cyclised N-methyl group1 is under investigation. One of us (R.H.H.) thanks the National Science Foundation U.S.A. for financial support. We are grateful to R.I.M.A.C. Cambridge Mass. for the gift of Hydrastis canadensis plants. (Received June 26th 1963.) See Gear and Spenser Canad.J. Chem. 1963,41,783. Barton Kirby and Taylor Proc. Chem. Soc. 1962 340; Barton Kirby Taylor and Thomas J.in the press. Perkin J. 1916 1025. Phares Arch. Biochem. Biophys. 1951 33 173. Biosynthesis of the “Berberine Bridge” By A. R. BATTERSBY M. HIRST and J. STAUNTON R. J. FRANCIS (THEROBERT LABORATORIES, ROBINSON UNIVERSITY OF LIVERPOOL) atom 8 of berberine (111) and of related optically active derivatives of base (I) which carry CARBON alkaloids is known1 as the “berberine bridge” and multiple labels. recently the proposal was made2 that this is formed in Nature by oxidative modification of an N-methyl group. The ring-closure could reasonably occur by way of the imine (II) or through similar processes.2 This proposal has been tested in the following manner. (A)-La~danosoline~ (I) was synthesised with a 14C-label at position 3 to act as a stable internal reference (64% of total activity) and also at the N-methyl group (36% of total activity).Administration of this precursor as the hydro- chloride to Brrberis japonica shoots yielded radio- active alkaloids and the isolated berberine (0.07% incorporation) was treated with phenylmagnesium br~mide.~ Permanganate oxidation of the derived phenyl base (IV) gave benzoic acid (34% of original total activity). These results and those of Barton Hesse and Kirby? establish that the “bridge” carbon atom arises from the N-methyl group of a J Ph Hog’ We are grateful to Mr. J. K. Hulme (Ness) and 1-benzylisoquinoline precursor. Further feeding ex- Mrs. M. R. Battersby for their help with plant periments are in progress with partially methylated cultivation.(Received July 24th 1963.) Sir Robert Robinson “The Structural Relations of Natural Products,” Clarendon Press Oxford 1955 p. 87. It emerged from discussions at the Summer School on Biosynthesis Milan 1962 that we and Professor D. H. R. Barton and Dr. G. W. Kirby had independently reached the same conclusion (Barton and Kirby collected lectures in the press); Battersby Tilden Lecture Proc. Chem. Soc. 1963 189; Barton Hugo Miiller Lecture Proc. Gem. Soc., 1963 in the press Robinson and Sugasawa J. 1932 789; Schopf and Thierfelder Annalen 1932 497 22. * Freund and Beck Ber. 1904,37 4673. Barton Hesse and Kirby Proc. Chem. Soc, 1963 preceding communication. The kindness of Professor Barton in sending us a copy of this communication in advance of publication is gratefully acknowledged.SEPTEMBER1963 269 ~ The Constitution of Nimbin By R. HENDERSON,R. MCCRINDLE,and K. H. OVERTON (THE UNIVERSITY GLASGOW) and M. HARRIS and D. W. TURNER (IMPERIAL LONDON) COLLEGE NIMBIN, isolatedl from various parts of the nim tree has been previously investigated notably by Narasimhan2 and by Sengupta et aL3 Its molecular formula C30H3609,2has recently been confirmed by mass-spectrometry.4 We have re-examined the recorded evidence and on the basis of additional chemical and nuclear mag- net ic resonance (n .m .r .) (spin-decoupling5) studies conclude that nimbin is a novel tetranortriterpenoid in which ring c is cleaved. The previously assigned3 oxygen groups namely a P-substituted furan an ap-unsaturated ketone one secondary acetoxyl and two methoxycarbonyl groups are fully confirmed by our n.m.r.results which also reveal a (cyclic) disecondary ether and a methyl group attached to a trisubstituted double bond. Nimbin is therefore tricarbocyclic and its basic C, carbon skeleton the /?-substituted furan ring and its five C-methyl groups (three at quater- nary carbon atoms one on vinyl and one oxidised to C0,Me) suggest a biogenetic relation to limonin.6 The following discussion is based on the partial structure (I; R = Me R' = Ac) which is rigorously established by our evidence and accounts for the portion C24H2909 of the nimbin molecule. Nimbin contains the chain -COCH=CHG since the vinyl protons of this system in nimbin and the corresponding diethyl ester (I; R = Et R' = Ac) m.p.174-176" [a] + 106" form a typical AB quartet (T 3-62 4.10; JAB 10 c.,kec.) and are not further coupled. In the decarboxylation product (11)3 obtained by alkaline hydrolysis of nimbin (examined as the acetate methyl ester m.p. 178-180" [a] + 178") the vinyl protons still form an AB quartet (T 3.52 4.20) but both are now further coupled to the new proton at position 4 which itself couples with a new secondary methyl group (T 8.73). This confirms the previously inferred3 substitution at position 4 and if we assume a euphol-derived structure locates the enone and one methoxy-carbonyl group in ring A (as I). The relation of the second methoxycarbonyl group to the enone system emerges from the constitution of pyronimbic (111) the pyrolysis product of dienol-lactone [A,,,.280 mp vmax (in CHCl,) 1747 cm.-l] shows an AB quartet arising from H2 and H3 consisting of a sharp doublet (H2; T 4.49 JAB 7 c./sec.) and a multiplet (H3; T 4.20) attribut- able to coupling with H, H (T7.12) and probably &I H also the vinyl-methyl group at C-4 (T 7.83). C-10 is therefore tetrasubstituted C-5 trisubstituted and ring c must be cleaved to provide the carboxyl function for enol-lactonisation. The remaining two oxygen atoms were located at positions 6 (acetoxyl) and 7 (ether) by formation of the enol-lactone y-lactone (IV) m.p. 265-270" [&ID + 13" Vmax (in CCl,) 1797 1768 cm.-l upon attempted acetyla- tion of the hexahydro(inc1uding furan)hydroxy- diacid derived from (I).H, H, and H form an XAB system (v 7.18 5-42 5.62 JAx 12 c./sec. JAB 3 c-jsec.) which implies the stereochemistry indicated and also that C-8 and C-10 are tetrasubstituted. This nimbic acid (I; R = R' = H). This homoannular Siddiqui Current Sci. 1942 11 278; Mitra Rao BhattacheFjee and Siddiqui J. Sci. Ind. Res. India 1947 6 B, 19; Mitra Rao and Siddiqui ibid. 1953 12 B 152; Bhattacherjee Mitra and Siddiqui ibid. p. 154. Narasimhan Chem. Ber. 1959 92 769. Sengupta Sengupta and Khastgir Tetrahedron,1960 11 67. Arya and Ryhage J. Sci. Ind. Res. India 1962 21 B 283. Turner J. 1962 847. Arigoni Barton Corey Jeger and collaborators Experientia 1960 16 41.PROCEEDINGS XAB system is clearly present in several nimbin band (near-equivalence) on irradiation of H derivatives; the X component appears at remarkably (r 7-62). low field in nimbin (T 6-25) and the diethyl ester The fragment C6H7 not accounted for in expres-(T 6.3) but moves upfield (T 7-75) in the decar- sion (I) contains the isolated hindered double bond boxylated derivative (11). Hydrogenation of nimbin of nimbin. The n.m.r. and chemical results which with platinum in acetic acid gave the fully saturated &-lactone0 m.p. 269-271 C29H4208 bear on this portion of the molecule are best ex- pressed as in formula (VI) which however is not O 0",f 1,[a vmax (in CCl,) 1738 1755s cm.-l whose formation supports the acetic acid side-chain at C-9 in nimbin i.e.cleavage of ring c between C-12 and C-13. This also follows from the n.m.r. spectrum of the 1,6-dione corresponding to (I; R = Me) m.p. 155-1 57" [a] + 139". The multiplet (2H) centred at T 6-23 from the 11-methylene group collapses to a narrow readily accommodated on biogenetic grounds. We are investigating these residual uncertainties. One of us (M.H.) thanks the D.S.I.R. for a maintenance award. (Received,June 29th 1963.) l70-Nuc1ear Magnetic Study of Xenic Acid By J. REUBEN SAMUEL and DAWD (THEISOTOPE THEWEIZMANN OF SCIENCE ISRAEL) DEPARTMENT INSTITUTE REHOVOTH H. SELIG*and JACOBSHAMIR (THE DEPARTMENT CHEMISTRY THEHEBREW OF INORGANIC AND ANALYTICAL UNIVERSITY JERUSALEM,ISRAEL) DUDLEY et aZ.l reported the hydrolysis of xenon hexafluoride in neutral or acid solution to a soluble xenon species which they have suggested was the hexahydroxide (xenic acid) Xe(OH), whose struc- ture is not yet clear.We have hydrolysed the hexafluoride in 170-enriched water (containing 7-33 atom % of 170) and obtained a colourless solution containing 1 milli-mole of the xenon species per ml. water and examined the 170nuclear magnetic resonance (n.m.r.) spectrum of this solution using a Varian DP 60 spectrometer operating at 8-13 Mc./sec. with slow passage. The derivative of the absorption mode was recorded. The modulation frequency was 40c./sec. and the modu- lation field 0.25 gauss (144.4 c./sec.). A single line was observed with a chemical shift of -278 f2 p.p.m.(water was used as internal reference). The line is extremely broad (420 c./sec.) and no fine structure could be observed. A solution of hydrogen fluoride of equivalent concentration in 170-enriched water (6 millimoles per ml. of water) was found to give no 170 n.m.r. absorption line apart from the water line. When an aqueous solution of xenon hexa-hydroxide (containing 1.5 atom % of I7O) was added to an equal volume of l70-enriched water * Permanent address Argonne National Laboratory. Dudley. Card. and Cadv. horn. Chem. 1963. 2 228. (containing 11-5 atom % of 170) the peak height of the 170 n.ni.r. line of the xenon-containing species was increased six-fold within the time necessary to make the fmt observation (3 minutes).The peak height did not increase further with time which indicates that exchange of 170 between the hexa- hydroxide and water is extremely rapid and at room temperature (23" h 1 ") is complete within three minutes. The 170-containing species was extracted into chloroform solution with an identical chemical shift. Malm et aL2 reported that this species can also be extracted into carbon tetrachloride. The 170chemical shift of xenon hexahydroxide is in the same range as those of perchloric acid3 (-288) and of bromate chlorate and perchlorate ions4 (-297 -287 -288). It appears from the chemical shift that the xenon-oxygen bonds have some double-bond character. Isotopic exchange of oxygen between perchloric acid and water was not found even in drastic conditions.Bromate and chlorate undergo5 an acid-catalysed exchange where- as periodic acid5 and periodate undergo isotopic exchange of oxygen extremely rapidly. (Received July 30th 1963.) Malm Holt and Bane in "Nible Gas Compouhds," ed. Hyman Univ. Chicago Press in the press. Christ Diehl Schneider and Dahn Helv. Chirn. Acta 1961 44 866. Figgis Kidd and Nyholm Proc. Roy. SOC.,1962 A 269,469. Brodskii and Vysotskaya Doklady Akad. Nauk. S.S.S.R. 1955,101,869; Hoering Butler and McDonald J. Amer. Chem. SOC.,1956,78 4829; Brodskii J. Chim. phys. 1958,55,40; Anbar and Guttmann J. Amer. Chem. Soc. 1961 83 781. SEPTEMBER 1963 27 1 The Constitutions of Taxicin-I and -II By D. H. Em 3'. W. HARRISON,R. M. SCROWSTON, and B.LYTHGOE OF CHEMISTRY LEEDS, (SCHOOL THEUNIWRSITY 2) O-CIMWMOYLTAXICIN-I~~~ gives3 with periodate the /I-diketone (I) and the cinnamate of an alcohol previously3 regarded as 4,5-diformyl-4-methyl-2-methylenecyclohexanol. The position of one of the two formyl groups in the latter structure is now shown to be incorrect. The trial m.p. 112" ob- tained by reducing the formyl groups gives a tri- acetate whose proton magnetic resonance (p.m.r.) spectrum4 showed coupled signals at T 5-73 (doublet J 7 c./sec. ;2H) and 7-26 (triplet J 7 c./sec. ; 1H). The methine group to which the latter is due must have the environment of position 3 in the structure (111); this requires the dialdehyde to have the structure (11). Alternative structures for 0-cinnamoyltaxicin-I may be derived by uniting the structures (I) and (11).We now report evidence which supports one alterna- tive namely the regular isoprenoid structure (IV ; R = R' = H). RO OR AcQ PAC CMe OMe OAc This work required the preparation of some new derivativesof taxicin-I and taxicin-II.2 O-Cinnamoyl- taxicin-I gave an isopropylidene derivative from which a monoacetate (IV; R,R = CMe, R' = Ac) m.p. 141-142" and a methyl ether (IV; R,R = CMe, R = Me) m.p. 180° were obtained. From the latter were prepared the diacetate (IV; R = Ac R' = Me) m.p. 194-195" and the allylic hydrogen- olysis product (V) m.p. 223-224" Amax. (in EtOH) 279 mp (E 5500). The aldehydo-acid (VI) m.p. 206-208 ",was obtained by periodate cleavage of the appropriate a-ketol.From 0-cinnamoyltaxicin-I1 triacetate? now formulated as (VII; R = Ac R' = CH:CHPh) were prepared the monoacetate (VII; R = H R' = CH :CHPh) m.p. 226225O the isopropylidene derivative (VII; R,R = CMe, R = CH:CHPh) m.p. 195" and the oxonortaxicin-I1 derivative (VII; R = Ac R' = CH,CH,Ph; =O in place of =CH,) m.p. 183".The chemistry and the spectral properties of these compounds suggested that taxicin-I1 differs from taxicin-I only in having a hydrogen atom in place of the tertiary 2-hydroxyl group. In confirma- tion periodate cleavage of the taxicin-11 derivative (VII; R = H R' = CH:CHPh) gave a dialdehyde whereas similar cleavage of the taxicin-I derivative (IV; R = H R' = Me) gave only a monoaldehyde the spectral data showing that the 8-aldehyde group had formed a cyclic (6-ring) hemiacetal with the tertiary hydroxyl group.Signal Position of 7 protons 4.0 q; J*9; 2H 7and 8 4-7 s; 2H 20 5-3 m; 1H 12 7-2 q; J 20; 2H 3 7.7 s; 3H 18 8.25 m; 4H 10 and 11 8.3 S; 3H 160r 17 8.75 S; 3H 160r 17 9.05 S; 3H 19 q = Quartet; s = singlet; m = unresolved multiplet; signals due to acetate cinnamate and hydroxyl protons are not recorded. * In c./sec. Examination of appropriate derivatives enabled all the signals in the p.m.r. spectnun5 of O-cin-namoyltaxicin-I triacetate to be assigned to the responsible hydrogen atoms (see Table) and this led to the following conclusions. (a) One of the two Baxter Lythgoe Scales Trippett and Blount Proc.Chem. Soc. 1958 9. Baxter Lythgoe Scales Scrowston and Trippett J. 1962 2964. Langley Lythgoe Scales Scrowston Trippett and Wray J. 1962 2972. P.m.r. data were determined for solutions in CDCI with a Varian A60 spectrometer. We thank Dr. A. Melera (Zurich) for a spectrum of this compound. possible ways of uniting the structures (I) and (11) is ruled out because both the carbon atoms flanking C-7 and C-8 are shown to lack a hydrogen atom. (b) The spectrum6 of the methyl ester of the acid (VI) which shows a triplet (J 1 c./sec.) CHO signal at T 0.25 together with the other data defines the sequence C-11 to C-15 inclusive. (c) In the spectrum of 0-cinnamoyltaxicin-I1 triacetate which is other- wise very similar to that of the taxicin-I analogue the proton at C-2 resplits the signals from those at C-15 and C-3 which establishes the sequence C-15 to C-4 inclusive.(4The results in general are com- patible with the structures (IV) for taxicin-I deriva- tives and in particular rule out the possibility that the enone system is further conjugated with an ethylenic link or a cyclopropane ring. PROCEEDINGS The chromophore of the taxicin-I derivative (V) was explored by hydrogenation (Pt-AcOH) which gave two isomeric dihydro-compounds. One m.p. 185-1 86”,was formed by reduction of the ethylenic link since it showed negligible absorption (E -400) at 200 mp and retained an unconjugated keto- group Vmax. 1700 cm.-l. In the second m.p. 206-207 * the keto-group had been reduced (no ketonic absorption; re-oxidation by chromic oxide to the precursor) and the ethylenic link retained.It had Amax. 224 mp (E 6400) a value as abnormal for an ethylenic link as is that of its precursor (279 mp) for an enone system. The nature of the environment which causes these abnormalities is being studied. (Received July 19th 1963 .) We thank Dr. Melera for this spectrum and double resonance data relating to it. The Vibrational Relaxation Time of the 3.3 p Band in Methane By T. L. COTTRELL and A. W. READ T. F. HUNTER (DEPARTMENT THEUNIVERSITY, OF CHEMISTRY EDINBURGH) LITTLEis known about the relaxation times at room temperature of higher-energy vibrational modes in polyatomic molecules mainly because the equi- librium population of such modes is very small.However if energy is put into a system of poly- atomic molecules by radiation of the appropriate frequency the collisional lifetime of a particular mode can be studied directly and the small popula- tion is no longer a disadvantage. We have used this principle to measure the relaxation time at room temperature of the 3.3 p band in methane in two independent ways. The first arose from an investigation of the absolute intensity of absorption by a method sug- gested by Mathes0n.l The energy absorbed is measured directly by noting the pressure rise on illumination in a constant-volume system under steady-state conditions and comparing this with the pressure rise obtained in the same system from a known input of electrical energy.At very short reduced-pathlength the energy absorbed should in- crease with the gas pressure in a predictable manner. However if the relaxation time for the vibrational mode concerned becomes comparable with the radia- tive lifetime of the band some energy will be lost by re-emission and the energy absorbed will fall below the value expected at low pressure. The 3.3 p band of methane shows this effect whereas chlorotri- fluoromethane which is expected to have a short relaxation time does not. This allows an estimate of 1.0 rt 0.5 x sec. to be made for the relaxation time of the 3-3 p band at 1 atm. provided wall collisions are not greatly more effective than gas collisions in de-exciting the vibration.Another estimate was obtained by using the optic- acoustic effe~t.~,~ In this experiment a sound wave is generated in a gas by illuminating it with infrared radiation interrupted at a sonic frequency. Relaxa- tion of the vibrational degrees of freedom results in a phase lag in the sound output. This was measured as a function of pressure in methane relative to the sound signal in chlorotrifluoromethane account being also taken of other pressure-dependent phase effects in the system. This allowed an estimate of 1.0 -f 0.3 x lo-* sec. to be made for the relaxation time of the 3.3 p band at 290”~ and 1 atm. In both experiments appropriate monochromation of the radiation by means of filters was used to isolate the bands concerned.It has been suggested recently4 that the optic- acoustic phase-lag method for determining relaxation times may not be feasible. There are certainly many difficulties in sorting out the relaxation phase lag from other pressure-dependent effects and the method developed here to overcome them will be described in a later p~blication.~ We hank the D.S.T.R. for maintenance grants to T.F.H and A.W.R. (Received July 18?h 1963.) Matheson Phys. Rev. 1932 40 813. Gorelik DokZady Akad. Nauk S.S.S.R.,1946,54 779. a Cottrell and McCoubrey “Molecular Energy Transfer in Gases,’ Butterworths London 1961 p. 45. Woodmansee and Decius J. Chem..Phys. 1962,36 1831. Cottrell Read and Young unpublished work. SEPTEMBER 1963 273 Structure and Reactivity of Tri~r~nyl-~-cyclo~n~~enylethylmoly~e~um By M.J. BENNETT and R. MASON (CRYSTALLOGRAPHY LABORATORY OF CHEMISTRY IMPERIAL COLLEGE LONDON) DEPARTMENT STUDIES of some transition-metal ethyl complexes of general formula rr-C,H,M(CO),C,H have been reported the preparation2 and reactions3 of n-C,H,Mo(CO),-C,H being of particular interest. A three-dimensional X-ray analysis of this complex has been completed (R= 0.095) and allows a com- parison to be made with the structure of bis(tri- carbonylcyclopentadienylmolybdenum)~ one of the products of its thermal and radiation decom-p~sition.~ From a theoretical viewpoint the bond lengths shown in the Figure provide data for an examination of the dependence of the metal-carbon bond order on the a-and n-bonding properties of the ligands.The average molybdenum-carbon (cyclopentadienyl) distance is 2.38 & 0.02 A the mean carbon-carbon bond length in the cyclo- pentadienyl ring being 1.43 Ic 0.04A. The molecular stereochemistry approximates to that of the (NbOF6)3- ion. The six bonding orbitals of the metal to the cyclopentadienyl and carbonyl ligands form a distorted octahedron the angles between the planes of the cyclopentadienyl ring and that of the three carbonyl-carbon atoms being 9.2"; the molybdenum-ethyl bond lies approximately along a three-fold axis of the octahedron the ethyl group being 0.67A above the carbonyl-carbon plane. In a (TaF,),- arrangement the alkyl group together with the two non-bonding lone-pairs would be in the equatorial plane whereas in the present structure the ethyl is some 0.5 A below this plane.The seven bonding and two non-bonding orbitals are apparently formed by a hybridisation scheme similar to that proposed for dihydrodi-n-cyclopentadienylmolyb-denum5 and we formulate a molecular-orbital model for the present complex elsewhere. The observed stereochemistryis consistent with the hypothesis that the lone pairs are sterically active a suggestion which accounts for the fact that these complexes are weak bases protonation being followed by the immediate loss of ethane and the replacement of the ethyl group by the acid anion.6 The difference of 0.41 A between the metal-ethyl and metal-carbonyl bond length is perhaps unex- pectedly large even when it is realised that approxi- mately 0-07A of this difference originates from the difference in atomic radii for the sp3-and the sp-carbon valency state.It is not obvious that the rr-bonding carbonyl ligands would lead to a suffici- ently large change in the molybdenum-carbon bond order to account for the corrected difference of 0.34 A between the metal-carbon bonds. Indeed the overall stereochemistry is more in keeping with the view that the o-bond is weaker for the molybdenum- ethyl bond than for the carbonyl interaction. The molybdenum-molybdenum bond length in bis(tri- carbonylcyclopentadienylmolybdenum)4 gives the metal radius as 1-61 A; from the sum of respective radii a length of 2.38 A is expected for the molyb- denum-ethyl bond in exact agreement with that observed.The present study indicates contrary to the suggestion by Wilson and Shoemaker that the lengthening of the metal-metal bond is due to in- creased "#'-electron character in this and the metal- ethyl bond rather than to steric strain from non- bonded carbonyl interactions. The only significant structural change accompanying the replacement of the ethyl group with a rr-C,H,(CO,)Mo residue is a 7" distortion in the angle at which the group enters. In both structures the Mo-C-0 bonds are sig-nificantly non-linear. Calculation of all non-bonded intra- and inter- molecular distances shows that the cyclopentadienyl rings of the reference molecule and its nearest neigh- bours are in closest contact with the ethyl group; the Davison McCleverty and Wilkinson J.1963 1133. * Piper and Wilkinson J. Inorg. Nucleur Chem. 1956,3 104. McCleverty and Wilkinson J. 1963 4096. Wilson and Shoemaker J. Chem. Phys. 1957 809. Ballhausen and Dahl Actu Chem. Scand. 1961 15 1333; Bennett Gerloch McCleverty and Mason Proc. Chem. SOC.,1962 357; Gerloch and Mason in press. Davison McFarlane Pratt and Wilkinson J. 1962 3653. ethyl groups of adjacent molecules in the crystal lattice are well separated. These observations explain why thermal decomposition of single crystals mainly involves ethyl attack on the cyclopentadienyl rings by a free-radical mechanism rather than the production of n-b~tane.~ Ready cleavage of the ethyl-molyb- denum bond is consistent with its low o-bond order a situation which will be modified (probably through PROCEEDINGS metal “8’-orbital contraction) in the more stable perfluoralkyl complex.We are grateful to Mr. 0. S. Mills and Dr. J. S. Rollett for supplying copies of their “Mercury” computer programmes. One of us (M.J.B.) is in receipt of a College Research Studentship. (Received July loth 1963.) Antimony Halides as Solvents. Part IILf Electron Spin Resonance Spectra of Aromatic Hydrocarbons in Antimony Trichloride By E. C. BAUGHAN, T. P. JONES,and L. G. STOODLEY (ROYALMILITARY COLLEGE OF SCIENCE SHRIVENHAM WIL’T S.) SEVERAL workers2 have used electron spin resonance to investigate the paramagnetic properties of aro-matic hydrocarbons in the presence of various Lewis and Bronsted acids the observed paramagnetism being attributed to a hydrocarbon positive ion formed by transfer of an electron from the hydro- carbon to the acid.In sulphuric acid which is most commonly used as a solvent for investigating hydro- carbon positive ions the first step is protonation of the hydrocarbon.2 Protonation cannot occur when antimony tri- chloride recently used for studying the ionisation of alkyl and aryl halides,lp3 is the solvent. We have shown however that when perylene naphthacene and pentacene are dissolved in freshly sublimed antimony trichloride at 75” (m.p. of antimony tri- chloride 73-2”) the coloured solutions gave well resolved electron spin resonance spectra.That the spectrum for perylene is that of its positive ion was shown by comparison with the spectrum of the hydrocarbon in 98 % sulphuric acid. The electron spin resonance spectrum of naphtha- cene positive ion in antimony trichloride differs from that in sulphuric acid* in that additional lines appear the change of solvent altering the splitting constants of the ring protons and so lifting the degeneracy observed in the latter solvent. The observed spectrum is explained for splitting constants of 5.20 1.78 and 1.04 gauss (probable error 373 i.e. in the ratio of 1~OOO:0~343:0~200, instead of l.OO0:0.333:0.204 for the positive ion in sulphuric acid. Of the theoretical 125 lines 105 are distinguishable. The change of splitting constants with solvent has been observed in other free-radical systems5 We have been unable to find a previous reference to the electron spin resonance spectrum of the pentacene positive ion.In sulphuric acid this ion is not suffici- ently stable for the spectrum to be recorded a second electron being removed from the hydrocarbon with the formation of a diamagnetic dipositive ion.* In antimony trichloride at 75” the spectra of pentacene and naphthacene decayed slowly over a period of some hours but the spectrum of perylene was unchanged after eight months. No coloured solution or electron spin resonance spectrum was observed with chrysene picene or pyrene in antimony trichloride. The spectra of the positive ions of anthracene and 9,lO-dimethyl-anthracene in this solvent have been observed by other workers and shown to be similar to the spectra of the corresponding ions in sulphuric acid.’ The formation of hydrocarbon cations is an oxidation and usually requires strong oxidising agents ;8 our preliminary results show that such cations are not formed if the solvent is completely free from oxygen or antimony pentachloride.Electron spin resonance measurements were made with a spectrometer operating at 9400 Mc./sec. with magnetic field modulation at 105 K.c./sec. We thank Dr. A. C. M. Finch for preliminary work on hydrocarbons in this solvent. (Received,June 26th 1963.) Part 11 Davies and Baunhan J. 1961 1711. Cf. Symons in “Advances in ‘?Physical Organic Chemistry,” ed.Gold Academic Press New York 1963. Porter and Baughan J. 1958 744. Hyde and Brown J. Chenz.Phys. 1962,37 368. Brown and Maki J. Chem. Phys. 1962 36 1944; Heineken Bruin and Bruin ibid.,1962,37,652. Carrington personal communication. * Finch personal communication. Weiss Nature 1941 147 512. SEPTEMBER 1963 275 Geminal Fluorine Spin-Coupling in Some Substituted Ethanes By J. DYER (DEPARTMENT OF TECHNOLOGY, OF CHJWXSTRY FACULTY UNIVERSITY OF MANCHESTER) As part of an investigation of the effect of hetero- The geminal coupling constant JAB,is dependent nuclei upon the nuclear magnetic resonance spectra on the Pauling electronegativity2 x (shown in the of organic compounds some substituted ethanes Table) of the heteronucleus at Q.JABis given by the have been studied of general formula CF,Q-CFHCl approximate relation JAB (c./sec.) M (5.4 x 102)/x. (cf. Table). Spectra were analysed as ABPX type and If we assume that increases in the electronegativity of where Q = PMe, as ABGKX by Lee and Sutcliffe’s Q are paralleled by reductions of the electron density meth0d.l The correspondence of magnetic and at C-1 it appeqrs that the magnitudes of spin- F(A? F(P) coupling constants are directly proportional to the \/ electron density between the coupling nuclei. (B) F-C-C.-H(X) (I) The author thanks Dr. J. Lee for helpful discus- cz/ > Derived spectral sions Messrs. A. E. Tipping J. Kirman and W. I. chemical formulce is shown in (I). parameters are shown in the Table. The methyl Bevan who prepared the samples and Mr.R. R. group absorption where present is complex and has Dean who supplied results for 1,2-dichloro-l ,1,2-not j7et been analysed. trifluoroethane. Calculated coupling constants (c./sec.) Q X (v&* lJABl IJAXI IJBXI lJAPl IJBPI lJPX1 (c./sec.) ___-__ SiCl 1.65 343 5.0 11.3 15.7 16.3 46.6 381.5 -338 ---SiMe PMe 1-85 278 4.8 10.7 17.2 15.9 47.6 280.6 PH2 -289 ---a3 3-05 175 3.7 5.0 15.5 15.4 48.1 156.3 SMe 2.65 222 5.1 6.6 18.8 18.1 49.0 152.1 OMe 3-60 142 3.3 4.6 12.0 11.2 48.8 34.0 Lee and Sutcliffe Trans. Farahy Soc. 1958 54 307. (Received June 5th 1963.) Daudel Lefebvre Moser “Quantum Chemistry,” Interscience Publ. Inc. New York 1959 p. 74. Dean unpublished result. * The internal chemical shift between the geminal fluorine resonance absorptions.New Fluorine Compounds of Xenon By A. J. EDWARDS and R. D. PEACOCK J. H. HOLLOWAY OF CHEMISTRY BIRMINGHAM, (DEPARTMENT THE UNIVERSITY 15) IN the chemistry of the noble gases attention has so single nuclear magnetic resonance peak at the melt- far been focussed mainly on the preparation struc- ing point recalls the behaviour of antimony penta- ture and hydrolysis of the fluorides of xenon. We fluoride itself at a similar temperature.2 The complex now report the preliminary results of a study of is also formed by interaction of antimony penta- certain chemical reactions of xenon tetrafluoride and fluoride and xenon difluoride. A similar straw- also the preparation of xenon difluoride by a flow coloured complex XeF2,2TaF, m.p.81’ is formed rneth0d.l by the action of tantalum pentafluoride on xenon Xenon tetrafluoride dissolves in liquid antimony tetrafluoride and Debye X-ray powder photographs pentafluoride with gas evolution to give a greenish suggest that the two are structurally related. It is solution from which a yellow diamagnetic complex interesting that a compound Xe(PtF,) has recently m.p. 63* XeF,,2SbFS is readily isolated. The com- been reported briefly by Ba~-tlett,~ and it seems pos- plex which can just be sublimed under a high sible that his material though much less stable than vacuum at 60° distils unchanged under a vacuum at our compounds will prove to be of similar constitu- -120° and is stable to higher temperatures. The tion. The diamagnetism of the antimony penta- Cf.Holloway and Peacock Proc. Chern. SOC.,1962 389. Hoffman Holder and Jolly J. Phys. Chem. 1958 62 364. PROCEEDINGS fluoride complex is evidence for a covalent perhaps difluoride4 in a 60-70% yield with only a little fluorine-bonded constitution F,SbFXeFSbF in the tetrafluoride. Small quantities of a more volatile solid compound. fraction mp. go" b.p. -115" also appear which Xenon tetrafluoride does not combine with boron preliminary experiments suggest may be the oxide trifluoride at temperatures up to 200" a point which difluoride XeOF,. has been observed independently by Bartlett? or with sodium or potassium fluoride. It dissolves in We are indebted to Imperial Chemical Industries diethyl ether with gas evolution to give a strongly Limited General Chemicals Division for the loan of oxidising solution.a fluorine cell. This work was carried out during the The action of fluorine on xenon at 250-400" tenure of a D.S.I.R. Fellowship (A.J.E.) and with oxygen or air as carrier gas in a flow methodl Studentship (J. H.H.). instead of nitrogen leads to the formation of xenon (Received June 20th 1963.) Bartlett Cheiii. Eng. News 1963,41,36. Hoppe Dahne Mattanch and Rodder Angew. Clzem. 1962,74,103;Weeks Chernick and Matheson J. Artier. Chem. SOC.,1962,84,4612. Dienyl and Homodienyl 1,5-Hydrogen Transfer in Cyclic Trienes and Homotrienes By DAVID S. GLASS,JOACHIM and S. WINSTEIN ZIRNER (CHEMISTRY DEPARTMENT CALIFORNIA) UNIVERSITY OF CALIFORNIA LOS ANGELES Q:= RELATIVELY easy intramolecular dienyl 1,5-hydrogen 3 transfer in cycloheptatriene at 100-140" was Q reported recently by ter Borg Kloosterziel and Van Meurs.1*2 This kind of transformation symbolised by (Ia + Ib) for the general case involving a de-localised 6-electron system in the transition state (lc) is of considerable theoretical and practical interest? We have observed similarly ready dienyl 1,5-hydrogen shifts and their homo-counterparts in some 8-membered cyclic trienes and 9-membered cyclic homotrienes.As summarised in the Table a first-order un-catalysed thermal isomerisation* of cycloocta- 1,3,6- 67 triene (IV) to the 1,3,5-isomer (111) may be followed conveniently at 100-130" in dilute solution in cyclo- hexane by measurement of its ultraviolet absorption.At 100" the rate constant is 1.24 x lo- sec.-l. An approximate rate constant observed for the iso- merisation in the gas phase in an evacuated bulb is 7-4x sec.-l very close to the value for the liquid phase. In view of these results and those of ter Borg Kloosterziel and Van Meurs with cyclo- heptatriene,l the isomerisation is most plausibly formulated by way of a dienyl l,S-shift.* The iso- merisation of the triene (IV) to (111) proceeds to an equilibrium mixture still containing a trace of (IV). Equilibrating either of the trienes as a neat liquid at 100" or 129" and vapour-phase chromatography (v.P.c.) of the resulting mixture shows the content of ter Borg Kloosterziel and Van Meurs Proc. Chem.SOC.,1962 359. See also Grundmann and Ottman Annulen 1953,582 163; Buchi and Burges J. Amer. Chem. Soc. 1962,84,3104. Wolinsky Chollar and Baird J. Amer. Chem. Soc. 1962,84 2775. See also (a) Cope and Hochstein J. Amer. Chetn.. Soe. 1950,72 2515; (b)Jones J. 1954 1808. * The same conclusion has been reached on qualitative grounds recently by J. L. Kice regarding the thermal isomerisa- tion of 5,8-di-(l-cyano-l-methylethyl)cyclo-octa-l,3,6-tr1ene to 3,8-di-(l-cyano-l-methylethyl)cyclo-octa-l,3,5-triene, this in turn giving rise to its bicyclic valency tautomer (J. L. Kice and T. S. Cantrell personal communication J. Amer. Chem. SOC.,1963,85 2298. SEPTEMBER 1963 277 (IV) to be in the range 0.5-1 %. Cycloocta-1,3,5-at 150-180" re-forms bicyclic material to the extent triene (111) equilibrates also with its bicyclic valency of ca.8-9%. These interconversions (VI + VII) tautome19~ (11) by way of a "homobenzene"-type may be considered as only one example of a homo- transition state (IIa) and this equilibration is con- variety of the dienyl 1,5-transfers formulated by siderably more rapid than (I11 + IV) (see Table). (Ia + Ib). The homodienyl case may be represented fg HL 2# by (VIIIa + VIIIb) the transition state being represented by (VIIIc). 5@ & 7 Competing with the homodienyl 1,5-shift of '/', 7 hydrogen from C-7 to C-3 in the bicyclodiene (VIb) 6 8 7 is a dienyl 3,5-shift from C-6 to C-2 depicted in (VIa) forming another isomer (V) the methylene H WC) (VI Ia) adduct of cyclo-octa-l,3,6-triene.This is reversible so that compounds (V VI and VII) are all brought The conversion of bicyclo[6,1,0]nona-2,4-diene (VI) into cis-cis-cis-cyclonona-l,4,7-triene(VII) was into equilibrium.5 While a complete kinetic analysis reported recently but its mechanism was not clear. has not been completed it is clear that the rate of The pure liquid diene (VI) A,, 234 m,u (log E the change (VI -V) is substantially smaller and the 3-78) prepared from cyclo-octa-1,3,5-triene is rate (V 3VI) is also somewhat smaller than (VI -Process I1 -IIIU Cyclohept atrienel I11 4 IVC IV 4Inc VI 4 VIId VII -VIa Temp. 1 29*4b Rate Summary 1o5k (sec.-l) Re1. rate 9100 1059l AH$ (kcalJmole-l) 24.7 As (e.u.) -2 129-4 0-078 1 311 -lo1 129.4 ca.0-2 2 100.0 1 *24 129.4 19.8 102*4 27.3 -8 121.2 1.6 129~4~ 3.5 45 149.8 23 129.4 ca. 0.2-0*3 3 Neat liquid. Estimated from data at other temperatures. Cyclohexane solution. Methylcyclohexane solution. transformed nearly completely into cis-cis-cis-cyclo- nona-1,4,7-triene (VII) on being held for a time at 150-1 80" under nitrogen. The relatively rapid first- order reaction may be followed for the neat liquid by nuclear magnetic resonance (n.m.r.) spectroscopy or in methylcyclohexane solution by V.P.C. (see Table). The formulation of the isomerisation by way of a 1,5-homodienylt7 shiftf of hydrogen from C-7 to c-3 in the bicyclodiene (mb) is supported by the behaviour of its 9,9-dideuterio-analogue.The first cyclononatriene which this material yields after 10 minutes at 152" has an appropriate n.m.r.spectrum with the vinyl :methylene Proton ratio of 1-45 f0.03 close to the theoretical value of 1.50 when allowance is made for slightly incomplete 9,9-deuteration of compound (VI). 3 The transformation WI) is not complete but is in fact reversible. The pure triene (VII) held VII). Thus homodienyl 1,5-transfer in (VI) is more rapid than dienyl 1,Rransfers in (V) or (VI). fl A.... ..-j Qs@ (VI r!iic) (Vltla) (VII Ib) From the Table it is clear that the 8-membered ring triene and the 9-membered ring homotriene systems are particularly suitableh3 for easy dienyl and homodienyl 1 ,5-shifts. For the transformations (VI +VII) the "saddle" conformations6 (VIc and WIa) seem stereoelectronically the most favourable.one of US (D.S.G.) is grateful for a Ehrkness Commonwealth Fund Fellowship and another (J.Z.) for a NATO Post-doctoral Fellowship. (Received July 2nd 1963.) Ziegler and Wilms Annalen 1950,567,23; Cope J. Amer. Cheni. SOC.,1952,744867. Radlick and Winstein J. Amer. Chem. SOC.,1963 84 344. t The transformation (Ia -+ Ib) has been described by W. R. Roth7 as an intramolecular En-synthesis and the con- version (VI 4VII) is therefore called a retro-En-reaction. Roth personal communication; Annalen in the press. 3 The analogous isomerisation of bicyclo[6,1,0]non-2-ene to cyclonona-1 ,Cdiene at 3 10" has been mentioned by Doering and Roth (Angew. Chem. 1963,75,27). § All the transformations (V f VI + vnr)have been observed by Roth7 in an elegant investigation ofthesecompounds but no kinetic studies were made.PROCEEDINGS Iodine Oxide Pentafluoride By R. J. GILLESPLE and J. W. QUAIL (DEPARTMENT MCMASTER HAMILTON CANADA) OF CHEMISTRY UNIVERSITY ONTARIO THE reaction of iodine heptaffuoride with silica at 100" in a sealed silica tube yields iodine oxide penta- fluoride IOF, a new compound of iodine(w1). The reaction was followed by means of 19Fnuclear mag- netic resonance spectroscopy. The extremely broad iodine heptafluoride resonance1 was gradually re- placed by a broad doublet and quintet on the low- field side of the relatively sharp doublet and quintet due to iodine pentafluoride as shown in the Figure.A small amount of iodine pentafluoride was present as an impurity in the heptafluoride. The intensities of the inner peaks in the new spectrum are enhanced because the ratio J/v,6 is relatively large. The observed intensities agree well with the theoretical intensities for an AB,spectrum given by Wiberg and NisL2 This spectrum clearly arises from a new compound containing four equi- valent fluorine atoms and a fifth non-equivalent fluorine atom. Since the chemical shift of the two multiplets is intermediate between those of iodine penta- and hepta-fluoride the only reasonable com- pound to which the spectrum can be attributed is iodine oxide pentafluoride. This is consistent with the nature of the reactants and with the fact that an analagous reaction is known to occur between xenon hexafluoride and silica to give xenon oxide tetra- fluoride XeOF4.3 As the reaction proceeded the nuclear magnetic resonance (n.m.r.) spectrum also showed the growth of a high-field line which is due to silicon tetrafluoride (identified by the 29Si satellites) the other product of the reaction.A very small peak that can presumably be attributed to hydrogen fluoride was also present. Iodine oxide pentafluoride is a colourless liquid. Preliminary studies on impure samples indicate a melting point in the range -10" to -20". It would be expected to have a not-quite-regular octahedral structure in which the angles between the axial and the equatorial fluorine atoms would be slightly smaller than 90"and the angles between the oxygen atom and the equatorial fluorine atoms slightly larger than 90" as a consequence of the greater repulsion exerted by the I0 double bond than by the IF single bonds.4 Temperature studies indicate that the very great line widths in the n.m.r.spectrum are due mainly to quadrupole broadening rather than to fluorine exchange. This shows that the iodine must be situated in a very symmetric environment which is consistent with the proposed octahedral structure (cf. C10,F)5. - I I I -50 -13 0 ppm H- N.m.r. spectrum (564 Mc./sec.; -15"). Chemical shijts measured from the centre of the IF quintet. It is noteworthy that the fluorine-fluorine spin- spin coupling constant Jn of -280 c./sec.is con-siderably larger than in iodine pentafluoride6 (Jm = 81 c./sec.). A similar increase in .Ippis observed on passing from a sulphur(rv) to a sulphur(v1) compound J,(SF,) '= 76.3 J,[SF,(SO,F),] = 156 c./sec. There may be a general increase in coupling constants with increasing oxidation state of the central atom. Only two other analogous seven-valent six-co- ordinate species have been reported previously ; rhenium oxide pentafl~oride~ and osmium oxide pentafluoride.1° We thank the Directorate of Chemical Sciences of the United States Air Force Office of Scientific Research for financial support and the National Research Council of Canada for the award of a Studentship (to J.W.Q.). (Received June 27th 1963.) Since submitting this communication the authors have been informed by Professor Neil Bartlett that he has obtained the pure compound and that Professor Cornwell has obtained similar results on the nuclear magnetic resonance spectrum of IOF to those described above.Gutowsky and Hoffman J. Chem. Phys. 1951 19 1259. Wiberg and Nist "Interpretation of NMR Spectra," W. A. Benjamin Inc. New Tork 1962. Chernick Claassen Hyman and Malm "Conference on Noble Gas Compounds Argonne National Laboratory Argonne Illinois U.S.A. April 22nd-23rd 1963. * Gillespie,J. Chem. Educ. 1963 40,295. Brownstein Canad.J. Chem. 1960,38 1597. Muetterties and Phillips J. Amer. Chem. SOC.,1957 79 322. Bacon Gillespie and Quail Cunud. J. Chem. 1963 41 1016. Shreeve and Cady J. Amer. Chem. SOC.,1961,83,4521.Aynsley Peacock and Robinson J. 1950 1623. loBartlett Jha and Trotter Proc. Chem. SQC.,1962 277. SEPTEMBER 1963 279 Nuclear Magnetic Resonance Method of Determining the Stereochemistry of Tertiary-PhosphinMetal Complexes By J. M. JENKINS and B. L. SHAW (SCHOOL THE UNIVERSITY OF CHEMISTRY LEEDS) TERTIARY phosphines are important ligands for stabilising a wide variety of transition-metal com- plexes and we now describe a nuclear magnetic resonance method for determining the stereochem- istry of many dimethylphenylphosphine complexes. This method could probably be extended to other phosphines e.g. triethylphosphine and diethyl-phenylphosphine by using proton-proton spin decoupling. The resonance of the methyl protons in free dimethylphenylphosphine is a symmetrical doublet due to spin-spin interaction with the phosphorus nucleus (,lP spin Q 100% abundance) but we find that when two molecules of this phosphine are present in a complex in trans-position to one another then this resonance is not a doublet but in the absence of rotational effects (see below) is usually a very well defined and narrow 1 :2 1 triplet; the methyl protons couple equally with both phosphorus nuclei with J (P-H) -4 c./sec.This is an example of “virtual coupling” of which there are several known cases in organic compounds1 and results because the two phosphorus atoms in trans-position couple strongly with each other. For the complex trans- [PdI,(PMe,Ph),] the methyl resonance is a 1 :2:1 triplet [7 7.78; J(P-H) 4.4 cJsec.1.With phosphorus ligands in cis-position the resonance of the methyl protons is split into a doublet by the phosphorus showing that the two phosphorus nuclei do not couple strongly; thus for cis-[PtCl,(PMe,Ph),] the resonance pattern is three symmetrical doublets [7 8-23; J(P-H) 11.1 c./sec. J(195Pt-H) 34.2c./sw.]. The resonance pattern of the methyl protons in the yellow complex [IrCI,(PMe,Ph),] is a 1 :2:1 triplet (7 8-09; J 4.5 c./sec.) and a symmetrical doublet (7 8.75; J 11.3 c./sec.) with intensity ratio triplet/ doublet of 2/1 showing two phosphines to be in Musher and Corev. Tetrahedron. 1962. 18.‘ 791. * Chatt Field and Shaw J. 1963 3371. mutual trans-positions as with other yellow iridium complexes of this type.Treatment of ruthenium trichloride in alcohol with carbon monoxide followed by addition of PMe,Ph (3 mol.) gave a yellow complex [RuC1,(CO)(PMe2Ph),] with a resonance pattern very similar to that of the yellow iridium complex and this together with the low dipole moment of 3.9 D indicates two phosphines to be in mutual trans- positions and the other to be in trans-position to carbon monoxide. On melting this complex iso- merised to a white complex with a resonance pattern of a narrow quartet and a symmetrical doublet with relative intensities of 2/1. This and the dipole moment of 7.4 D indicate two phosphine groups in mutual trans-positions and the third in trans-position to chlorine restricted rotation about the Ru-P bond causing the two methyl groups on the same phosphorus atom to be non-equivalent.The methyl groups are equivalent even with restricted rotation in the yellow isomer because of the plane of symmetry through the Ru-P bond. We have pre- pared several other complexes showing resonance patterns of these types and have thus determined their stereochemistry. This nuclear magnetic reson- ance method may be used for complexes soluble only in polar solvents and for salts (when dipole moments cannot be used). Thus the methyl proton resonance pattern of the pink anion [IrCl,L2] (L = PMe,Ph) analogous to the pink anions with L = PEt or PEt2Ph2 or L = AsMePh,? is a 1 :2 1 triplet with 7 8.05 [J(P-H) 4.0 cJsec.1 indicating a trans-configuration.We are indebted to Dr. N. Sheppard for valuable discussion to the D.S.I.R. for a grant and to Imperial Chemical Industries Limited for measuring the dipole moments. (Received July 25th 1963.) Nyholm and Dwyer J. Proc. Roy. SOC.New South Wales 1945,99 121. Configurational Correlation of Desosamine and Chalcose By A. B. FOSTER,M. STACEY and J. H. WESTWOOD J. M. WEBBER DEPARTMENT BIRMINGHAM, (CHEMISTRY THE UNIVERSITY 15) the 4,6-dideoxy-3-0-methylhexosel CHALCOSE com-on the basis of nuclear magnetic resonance and ponent of the antibiotics chalcomycinl and lanka- chemical evidence.le3 We now report the conversion mycin2 has been assigned the D-xylo-configuration of desosamine (3,4,6-trideoxy33-dimethy1amino-~-l Woo Dion and Bartz J.Amer. Chem. Soc. 1961 83 3352. Keller-Schierlein and Roncari Neb. Chim.Acta 1962 45 138. Woo Dion and Johnson J. Amer. Chem. SOC.,1962,84 1066. PROCEEDINGS xylo-hexopyranose4) (I) the amino-sugar component pyranoside (111) and ethyl 4,6-dideoxy-2-0-methyl- of the macrolide antibiotic erythromycin into chal- a/harubo-hexopyranoside. Thin-layer chromato- cose and thereby substantiate the configurational graphy of this mixture revealed two major com-assignment. A similar conclusion was reached by a ponents (xylo-isomers RF 0.28 ; avubo-isomers R synthesis of chalcose from D-glucose which was 0.65),and hydrolysis with N-sulphuric acid at 95" for reported5 whilst the above work was in progress. 3 hr. gave a mixture of reducing sugars [R values 0.74 and 0.84 (cf.chalcose RF 0.74) in paper CH chromatography with the organic phase of butanol- ethanol-water (4 1 :5) and detection with aniline hydrogen phthalateQ]. Chalcose and the reducing sugar with R value 0-74 underwent the same characteristic series of colour changes with aniline (I) CH hydrogen phthalate. R=Et) Fractionation of the glycoside mixture on neutral (a (iV; R=H) alumina (Brockmann grade 111) gave with ether the D-arabo-compounds and subsequently with methanol the D-xyb-glycosides ;the fractions appeared homo- The methiodide of ethyl aP-desosaminide6 gave geneous on thin-layer chromatography and they with moist silver oxide a methohydroxide which on were present in the approximate ratio xy2o:urabo of pyrolysis7 at 80-200"f12 mm.afforded the ribo- 2.5 :1. Acidic hydrolysis of the D-xylo-glycosides epoxide (11) b.p. 74-84"/12 mm. (Found C 60.35; gave a product which after sublimation at H 9.05. CSHI4O3 requires C 60.7; H 8.9%). The 70-80"/0- 1 mm. and recrystallisation from ether- epoxide appeared to contain one major component light petroleum (b.p. 60-80") had m.p. 91-94" with traces of unidentified substances on examina- alone or in admixture with authentic1 chalcose (m.p. tion by thin-layer chromatography. Cleavage of the 92-96") [a] + 130" (c 0.4 in H,O; 3 min.) -epoxide with boiling methanolic sodium methoxide +78" (equil. 3 hr.) and an infrared spectrum (KBr) for 3.5 days and removal from the product of vicinal indistinguishable from that of chalcose (IV). diol contaminants by oxidation with periodate followed by absorption8 of the resultant aldehydes The authors thank Dr.Quentin R. Bartz of Parke on Amberlite IRA-400(HO- form) gave a mixture of Davis & Co. for a sample of natural chalcose. 4,6 -dideoxy -3 -0-methyl -aP -D -xylo -hexo-(Received,July 23rd 1963.) Bolton Foster Stacey and Webber J. 1961 4831; Chem. and Znd. 1962 1945; Richardson Proc. Chem. Soc., 1963 131. Kochetkov and Usov Tetrahedron Letters 1963 519. Flynn Sigal Wiley and Gerzon J. Amer. Chem. Soc. 1954 76 3121. Paul and Tchelitcheff Bull. Soc. chim.France 1957 1059; cf. Newman Chetzz. and hd. 1963 372. * Foster Inch Lehmann Stacey and Webber J. 1962 2116. Partridge Natiire 1949 164,443. The Constitution of Crotonosine By L. J. HAYNES and K.L. STUART (UNIVERSITY KINGSTON OF THE WESTINDIES 7 JAMAICA) and D. H. R. BARTON and G. W. KIRBY (IMPERIAL LONDON, COLLEGE S.W.7) RECENTLY~ the constitution (I) was suggested for revealed the presence of one aromatic hydrogen crotonosine the major crystalline alkaloid of C. (3.42 T)andfour olefinic protons. In agreement with linearis Jacq. A more thorough examination of this diacetyltetrahydrocrotonosineshowed only one nuclear magnetic resonance (n.m.r.) data coupled aromatic proton as a singlet (3.20 7).The olefinic with the earlier1 chemical evidence has shown that protons of crotonosine gave multiplets centred at r crotonosine has in fact the formula (11; R = R" = values of ca. 2.9 and ca. 3.8 arising from the two H R' = Me) or (II; R = R/= H R = Me).The overlapping AB quartets of the and a protons of former is preferred on biogenetic grounds? an unsymmetrical 4,4-disubstituted cyclohexa-2,s- The integrated n.m.r. spectrum of crotonosine dienone. Transannular coupling (Jaat 1 -5 C.P.S. ; Haynes and Stuart J. 1963 1784 1789. Barton and T. Cohen "Festschrift A. Stoll," Basel 1957 p. 117. SEPTEMBER 1963 J@r,2.5 c.P.s.) of the 01 and protons was also apparent. The spectrum of diacetylcrotonosine con- firmed these assignments. Dr. W. von Philipsborn (Zurich) who has made a special study of cyclo- hexadienone systems,3 kindly agreed with our assignments. 8 (I) @> OMe (m) R~+JJJR~~\ Me0 R‘O Meo&Me3i (W (v) Further inspection of the n.m.r. spectrum of NO-diacetyl-0-methylapocrotonosine,l formerly re- garded as(111; R = R’ = Ac) demonstrated that the deshielded* aromatic proton [asterisk in (IV; R or R’ == R’ = Ac R’ or R = Me)] appearing at 1.95 T showed meta coupling (J 2.5 c.P.s.) with the upfield von Philipsborn Helv.Chim. Acta in press. Goodwin Shoolery and Johnson Proc. Chem. Soc. 1958 306. Goto Annalen 1936 521 175. Bernauer Helv. Chim. Acta in press. The Anomalous Magnetic Behaviour of Some Chromous Compounds By A. EARNSHAW 28 1 components of the AB quartet produced by the remaining ortho protons in the same ring. The spectra of N-acetyl-00-dimethylapocrotonosine (IV R = R = Me R” = Ac) and the phenanthrene (V) were entirely in accord with this interpretation. The former compound should be N-acetyl-0-methyl-tuduranine5 and the physical constants are in good agreement.Through the helpful collaboration of Dr. W. von Philipsborn we came to learn of important work by Dr. Karl Bernauer of Hoffmann-La Roche Basel on pronuciferin a new alkaloid from the Asiatic lotus. Dr. Bernauer has very kindly sent us a copy of his preliminary communication6 which shows that pro- nuciferin is (11; R = R’ = R’ = Me). It should therefore be1 “base A,” which is NO-dimethyl- crotonosine. It is gratifying that although a direct comparison has not yet been made there is complete identity of physical constants. We thank Drs. W. von Philipsborn and K. Bernauer for courteous exchange of information. The n.m.r. spectra were taken on a Varian A60 spectrometer on permanent loan to one of us (D.H.R.B.) from the Wellcome Trust.(Received Jury 19rh 1963 .) L. F. LARKWORTHY, and K. S. PATEL COLLEGE LONDON, BATTERSEA OF TECHNOLOGY S.W.11) (DEPARTMENT OF CHEMISTRY and STRUCTURAL magnetic similarities between compounds of the d4-and d9-ions chromium(1r) and copper(@ are well known. The magnetic data avail- able on chromium(I1) are very sparse compared with those on copper(u) probably owing to preparative difficulties and are apparently confined to measure- ments at single temperatures.l We have prepared a series of chromous compounds under air-free con- ditions and report here their magnetic properties over a range of temperatures we believe for the first time.The results throw light on possible structures of these compounds. Chromous oxalate (anhydrate and monohydrate) prepared by the method of Lux and Illmann2 has a moment falling from 4.5 B.M. at 340”~ to 4-0B.M. at lOo”~,suggesting appreciable metal-metal inter- act ion. The anhydrous benzoate like the a~etate,~ is more nearly diamagnetic and a similar binuclear structure seems likely. The increase in susceptibility below about 260”~ is probably due to the presence of traces of chromic ion or chromous ion in a mononuclear form. As little as 0-5% of the chromium in a mono- nuclear form would be sufficient to account for this behaviour. The formate is the most interesting of all in that it appears to occur in two forms; a blue probably mononuclear form and a red probably binuclear Foex Gorter and Smits “Constantes Selectionnkes Diamagnetisme et Paramagnetisme,” Mason et Cie Paris 1957; Costa and Pwteddu,J.Znorg. NucZear Chem. 1958,8,104; Lewis and Wilkins “Modern Co-ordination Chemistry,” Interscience Publ. Inc. New York 1959. Lux and Illmann Chem. Ber. 1958,91,2143. King and Garner J. Chern. Phys. 1950 18 689; Niekerk Schoening and Wet Acta Cryst. 1953 6 501. Temp (4 FIG.1. Magnetic behaviour of (A) CrC,O,,H,O (B) blue Cr(O,C-H), (C) CrC1,,4H20 and (D) CrSO4,5H2O. form. Precipitation from aqueous solution yields the red monohydrate. At 1 OO"c,under reduced pressure dehydration occurs without change in colour but at about 140"c the colour changes to blue.The red anhydrate has a moment falling from 1.2 to 0-7B.M. whereas the blue anhydrate has a moment of 4-8 B.M. virtually independent of temperature. Com- parable behaviour is also noted with the hydrated formates. For comparison we have also prepared the salts PROCEEDINGS CrC1,,4H20 and CrS04,5H,0 which show normal Curie-law behaviour with moments between 4.9and 5.0 B.M. independent of temperature. These results are summarised in Figs. 1 and 2 in the conventional manner by plotting 1 /xas a function of temperature. w I I 1 I SO' 160" 240' 320. Temp. (K) FIG.2. Magnetic behaviour of (A) Cr(OBz) and (B) red Cr(0,C-H),. One of us (K.S.P.) thanks C.V.M. Vallabh Vidyanagar (India) for study leave during which this work was carried out.(Received July 16tk 1963.) Hydrogen-transfer Catalysed by Some Group VIII Metal Complexes By J. K. NICHOLSON and B. L. SHAW (SCHOOL THEUNIVERSITY, OF CHEMISTRY LEEDS) WE have found a chlororuthenium(n) complex to be an extremely powerful catalyst for hydrogen transfer with allylic alcohols. Thus boiling a 2 x 10-3~-solution of ruthenium trichloride in 50% aqueous allyl alcohol causes reduction to the bivalent state followed by the vigorous evolution of propene; acraldehyde and propionaldehyde are also formed in similar yield to the propene and were identified as their 2,4-dinitrophenylhydrazones.Thus the ruthen- ium@) catalyst promotes both intermolecular (1) and 2CH,:CH.CH2*OH-+ CH,:CH*CH + CH2:CH.CH0 + H,O .. . (1) CH,:CHCH2-OH -+ CH,*CH,*CHO . . . (2) intramolecular hydrogen-transfer (2) and in these conditions the two reactions are of comparable im- portance. We believe a ruthenium(I1) complex to have been the catalyst since addition of pyridine in the early stages readily gave the known complex [RuCI,(C,H,N),]~ in high yield. With solutions of ruthenium trichloride in boiling allyl alcohol pro- pene was evolved and the catalyst efficiency increased markedly with dilution (see curves 14); with a 4.5 x 10-4-~-solution 1450 moles of propene per g.-atom of ruthenium were evolved after 3 hr.; pro- pionaldehyde diallyl acetal was also formed but was not estimated. The catalyst efficiency falls off with time presumably owing to formation of ruthenium complexes with some of the products of the reactions e.g.condensation products from the aldehydes- Ruthenium trichloride promotes hydrogen-transfer with other allylic alcohols and propargyl alcohol ; 2-methylallyl alcohol was converted into isobutene methacraldehyde and isobutyraldehyde (see curve 5); but-2-en-1-01 gave ethyl methyl ketone and a mixture of n-butenes; cis-but-2-ene-l,4-diol gave crotonaldehyde; propargyl alcohol gave a 1:1 mix- Abel Bennett and Wilkinson J. 1959 3178. SEPTEMBER 1963 283 c25OOl-? P P P 114 0’ c3 I I r\ -Q I I 2 3 Time (hr) Rates of evolution of gas from boiling solutions of metal complexes in unsaturated alcohols Time (hrs.) -f Propene from allyl alcohol-RuC1,,3H20 (1) 8 x ~O”M-, (2) 4 x ~O-,M- (3) 2 x ~O-,M- and (4) 4.5 x 104~-solution.(5) Isobutene from 2-methvlallvl alcohol-RuC1,,3H20 (4 x 10-3~). (6) Ethylene -bnd carbon monoxide from RuC1,,3Hz0 (4 x ~O-,M) in 1:l pro-pargyl alcohol-acetic acid. (7) Propene from allyl alcohol-RhCl3,3HZO(4 x ~O-,M). Smidt and Hafner Angew. Chem. 1959,71 284. ture of ethylene and carbon monoxide (see curve 6) but we have not yet identified the non-gaseous products of this reaction. Rhodium trichloride with allyl alcohol gave a red rhodium(n1)-ally1 alcohol complex readily reduced by an excess of allyl alcohol to a yellow rhodium(1) complex [Rh2C12(C3H,.0H)4]. Catalytic quantities of this complex (or of rhodium trichloride) when heated with allyl alcohol gave propene (see curve 7) acraldehyde and propionaldehyde but the efficiency was much less than with ruthenium trichloride.It has been reported that palladium chloride with ally1 alcohol gives palladium allplpalladium chloride acraldehyde and propene.2 We find that the amount of propene formed is more than the stoicheiometric amount; in a typical reaction it amounts to about four moles per g.-atom of palladium and is formed presumably by intermolecular hydrogen transfer similar to the above; the final product allylpalladium chloride does not catalyse hydrogen-transfer re- actions of allyl alcohol. We are much indebted to Imperial Chemical Industries Limited for financial assistance. (Received June 29th 1963.) Evidence of Electron-exchange between the Triphenylmethyl Radical and Triphenylmethyl Cation in Solution By J.W. Lorn OF CHEMISTRY OF ALBERTA ALBERTA, (DEPARTMENT UNIVERSITY EDMONTON CANADA) ELECTRON paramagnetic resonance (e.p.r.) spectro- scopy has been used to measure electron-exchange rates in solution between free radicals and their corresponding negatively charged species1 and be-tween radical anions and their parent uncharged species2 We now report the establishment of equi- librium between the triphenylmethyl radical and its cation in acetic-trifluoroacetic acid solution and an estimate of the second-order rate constant. The triphenylmethyl radical generated from a de- gassed solution of triphenylmethyl bromide in this acid solution by the action of mercury forms a stable solution which provides a well-resolved e.p.r.spectrum that does not change appreciably on addi- tion of small proportions of trihoroacetic acid although larger amounts cause substantial line broadening and loss of hyperfine structure. In 3 :7 v]v trifluoroacetic-acetic acid the e.p.r. spectrum was substantially the same as in acetic acid. Similarly the spectrum of the free radical was unaffected by addition of a large excess of triphenylmethanol to an acetic acid solution consistently with the negligible concentration of the carbonium ion in this solvent shown by the absorption spectrum. However when triphenylmethyl cation was introduced into the solu- tion (with triphenylmethanol in the presence of tri- fluoroacetic acid) line broadening and loss of hyper- fine structure resulted (see Figure).We attribute the line broadening to the electron-exchange Ph,C-+ Ph3C+ + Ph3C+ + Ph,C.. At constant concentration of free radical (to avoid concentration -dependent exchange narrowing effects) successively higher concentrations of the alcohol resulted in a linear increase in line broaden- ing implying that the reaction is of the first order with respect to carbonium ion. The extent of broad- ening is immediately apparent by comparison with the standard sample in the dual cavity run under the same conditions differing only in the absence of alcohol. As our solutions obeyed the Beer-Lambert Thomas and Weissman J. Amer. Chem. SOC.,1962,84,4269. Ward and Weissman J. Amer.Chem. SOC.,1957,79 2086. Law the concentration of the ion was measured by comparing the absorption at 4200 A in our solutions with that of solutions of the alcohol in 98 % sulphuric acid which had the same line shape.3 In accordance with the treatment of Ward and Weissman2p4 we measured AH (the line breadth n . t-----l" . I gauss Varian dual-sample caviry e.p.r. traces. First derivative absorption of the central region of the spectrum of tnjlhenylmethyl radical in 317 vlv CF~*CO,H-ACOH. (1) 7 x 10-3~-triphenylmethyl.(2) The same in the presence of 7 x 10-2~-triphenylrnethanol(7.9 x 10-3~ rvirh respect to rriphenylmethyl cation). Evans McEwan Price and Thomas J. 1955 3098. * Weissman 2.Electrochem. 1960,64,47.Fairbourn and Lucken J. 1963,258. Chestnut and Sloan J. Chem. Phys. 1960 33 637. PROCEEDINGS between points of extreme slope in the absence of exchange) by comparing the triphenylmethyl radical in 3 :7 trifluoroacetic-acetic acid with the hyperfine splitting of the p-benzosemiquinone radical in alkaline ethanol solution (taken to be 2.368 g.5). Under our conditions it was 0.076 gauss to be com- pared with the value of ca. 0.05gauss estimated by Chestnut and Sloan6 for a 10-3~-solution of the radical in toluene between -20" and -50". From the slope of the appropriate linear plot the second-order rate constant at about 25O was esti- mated to be 1.3 x 108 ].mole-l sec.-l. The result suggests the possible utility of this method for the detection of carbonium-ion inter- mediates and for estimating their concentration thereby confirming heterolytic reaction mechanisms.I am indebted to Professor L. M. Jackman of the University of Melbourne for suggesting thesc experiments. (Received June loth 1963.) NEWS AND ANNOUNCEMENTS Research Fund.-The Research Fund of the Chemical Society provides grants for the assistance of research in all branches of Chemistry. Applications for grants will be considered in December 1963 and should be submitted on the appropriate form not later than November 15th 1963. The total amount available for distribution is approximately &I ,OOO and applications from Fellows will receive prior consideration. Forms of application together with the regulations governing the award of grants may be obtained from the General Secretary.Corday-Morgan Memorial Fund Executive.-The Corday-Morgan Memorial Fund Executive is to sponsor two tours to Africa during the winter 1963-64. Professor R. A. Raphael F.R.S. Regius Professor of Chemistry in the University of Glasgow is to visit Commonwealth territories in East Africa including Uganda Tanganyika and Kenya and Professor G. W. Kenner Heath Harrison Professor of Chemistry in the University of Liverpool will tour Commonwealth countries in West Africa. The Corday-Morgan Memorial Fund originates from a bequest to the Chemical Society by Sir Gilbert Morgan a past President who died in February. 1940. The Executive consists of the Presidents and the immediate past Presidents of the Chemical Society the Royal Institute of Chemistry and the Society of Chemical Industry and its purpose is to promote the unification of the chemical profession within the Commonwealth.It seeks to achieve this object by the appointment from time to time of a lecturer to visit some desig- nated area of the Commonwealth overseas. In general the visitor will tour the main academic and where appropriate industrial centres to give informal colloquia as well as formal lectures and to discuss problems of mutual interest in the countries visited. The Corday-Morgan Medal and Prize.-This Award consisting of a Silver Medal and a monetary Prize of 400 guineas is made annually to the Chemist of either sex and of British Nationality who in the judgement of the Council of the Chemical Society has published during the year in question and in the immediately preceding five years the most meritorious contribution to experimental chemistry and who has not at the date of publication attained the age of thirty-six years.If in the opinion of the Council two or more candidates are of equal merit SEPTEMBER 1963 a medal may be awarded to each and the prize divided equally among them. Copies of the rules governing the Award may be obtained from the General Secretary of the Society. Applications or recommendations in respect of the Award for the year 1962 must be received not later than December 31st 1963 and applications for the Award for 1963 are due before the end of 1964.The Perkin Centenary Trust.-The Perkin Cen- tenary Fellowship for 1963 has been awarded to Mu. N. S. Rao of India and will be tenable from October 1st next in the Chemistry Department at the Imperial College of Science and Technology London. Perkin Centenary Scholarships have been awarded to Mr. H. A. J. Butterworth of Ashton-under-Lyne tenable at the Royal College of Advanced Tech- nology Salford and to Mr. C. R. Laycock of Bradford tenable at the Liverpool College of Technology. Library.-The cost of photocopies has been standardised at one shilling per page for both Xerox prints and microfilm. The substantial increase in the cost of film is due to the fall in demand since the Xerox service commenced rendering the pro- duction of film uneconomic.Microfilm can be supplied where specifically requested but the service will be slower than that provided by Xerox prints. Election of New Fellows.-79 Candidates were elected to the Fellowship in August 1963. Deaths.-We regret to announce the deaths of the following Mr. S. H. Collins (15.3.63) Worthing a Fellow since 1890; Mr. R. Dodd (14.7.63) formerly Managing Director of Erinoid Limited Stroud ; Dr. J. J. Sudborough (25.7.63) formerly Professor of General and Organic Chemistry lndian Institute of Science Bangalore and a Fellow since 1890; and Mr. R. M. Winter (6.6.63) formerly Research Controller Imperial Chemical Industries Limited. International Symposia etc.-A Conference on Solid State Physics will be held in Bristol on January lst4th 1964.Further enquiries should be addressed to the Administration Assistant The Institute of Physics and The Physical Society 47 Belgrave Square London S.W.1. A Conference on High Energy Physics arranged by the Institute of Physics and the Physical Society will be held in Didcot Berkshire on April 15-17th 1964. Further enquiries should be addressed to the Administration Assistant The Institute of Physics and the Physical Society 47 Belgrave Square S.W. 1. The Eighth International Congress of Soil Science will be held in Bucharest on August 31st to September 9th 1964. Further enquiries should be addressed to Comit6 Roumain d’organisation VITIme Congr6s International de la Science due Sol Bd.Marasti No. 61 Bucharest 33 Rumania. The Third European Symposium on Chemical Reaction Engineering under the auspices of the European Federation of Chemical Engineering the “Koninklijk Instituut van Ingenieurs,” and the “Koninklijke Nederlandse Cliemische Vereninghg,” will be held on September 15-17th 1964. Further enquiries should be addressed to Dr. J. Hoogschagen c/o A.K.U. N.V. Velperweg 76 Arnhem Nether- lands. A Symposium on Surface Activity and the Microbial Cell will be held in London on Septeaer 24-25th 1964. Further enquiries should be addressed to the Honorary Secretary Symposium Surface Activity and the Microbial Cell Society of Chemical Industry 14 Belgrave Square London s.w.l. The Tenth Conference on Magnetism and Magnetic Materials sponsored by the American Institute of Physics and Institute of Electrical and Electronic Engineers will be held in Minneapolis on November 16-19th 1964.Further enquiries should be addressed to the Secretary Institute of Electrical and Electronics Engineers Box A Lenox Hill Station New York 21 N.Y. Personal.-Dv. J. C. Bevington formerly of the University of Birmingham has been appointed to the Chair of Chemistry in the new University of Lancaster. Dr. M. D. Carr has been appointed to a Lecture- ship in Chemistry at the Victoria University of Wellington New Zealand. Dr. W. 0.Davies has resigned as Lecturer in Chemistry at ShefField College of Technology to take a Senior Lectureship in Inorganic Chemistry at Portsmouth College of Technology.Dr. E. D. M. Eades has accepted a Visiting Scientists Resident Research Associateship awarded by the U.S. Academy of Sciences and tenable at the U.S. Army Laboratories in Natick Massachusetts. Mr. W.J. Feast and Mr. B. E. Job have been appointed Research Fellows in the Chemistry Department of the University of Birmingham. Mr. R. V. Foster has been awarded a Research Scholarship in Medical Chemistry at the Australian National University Canberra. Dr. F. Hartley Dean of the School of Pharmacy London has been appointed to the Government Committee on the Safety of Drugs. Dr. R. E. Hester has completed his period as N.A.T.O. Research Fellow in the Inorganic Chemistry Department Cambridge University and has been appointed Assistant Professor in the Department of Chemistry at Cornell University Ithaca N.Y.U.S.A. Mr. A. W. Jackson formerly with Beecham Group Limited has joined Eli Lilly International Corporation as a Market Research Associate. Dr. Brynmor Jones has been appointed Chairman of the Audio-visual Aids Committee set up by the University Grants Committee the Ministry of Education and the Scottish Education Department. Dr. W.Idris Jones retires from the National Coal Board as from October 1st. Mr. N. Lindop has resigned from the Kingston College of Technology to become Principal of the South-West Essex Technical College and School of Art,Walt hamstow. Qr. G. G. Lowry formerly of Michigan State University has been appointed Assistant Professor of Chemistry at Claremont Men’s College California.Professor R. S. Nyholm spoke on “Some Aspects of Modern Inorganic Chemistry” when giving the 3M (Canada) Special Lecture Series in Chemistry at the University of Western Ontario London Ontario in September 1963. Professor R. S. NyhoZm has been appointed to the Headship of the Department of Chemistry at University College London. Dr. R. 0.Ragsdale formerly of the Allied Chemical Corporation has been appointed Assistant Professor at the University of Utah. Dr. C. N. R. Rao is now Associate Professor of Chemistry Indian Institute of Technology Kanpur India. Dr. H. D. C. Rapson has resigned his post as Head of the Physical Chemistry Department Beecham Research Laboratories (Research Division) and has been appointed Reader in Pharmaceutical Chemistry (Physical Aspects) at the Chelsea School of Pharmacy.PROCEEDINGS Mr. T. D. Smith formerly of the University College of North Wales has been appointed Senior Lecturer in Chemistry in Monash University Melbourne. Professor F. Sondheimer Head of the Chemistry Department of the Weizmann Institute of Science has been appointed Royal Society Research Professor in the Chemical Laboratory of the University of Cambridge and takes up his appoint- ment during 1964. Dr. B. I;. Tonge formerly of Plymouth College of Technology has been appointed Research Manager to Pure Chemicals Limited Liverpool. Dr. J. Trutfer of the University of British Columbia has been awarded the D.Sc.degree by the University of Glasgow. Dr. J. I?.P. Tyman has been appointed Lecturer in Organic Chemistry at Brunel College. Professor R. L. Wainhas been named as one of the 1963 winners of the John Scott awards for his production of a group of selective weed-killers causing less damage to crops particularly cereals and legumes. Dr. D. L. H. Williams has been appointed Lecturer in Physical Chemistry at the University of Durham. Dr. R. 0.Wi1liunt.sis now a Technical Officer in the Research Department Heavy Organic Chemicals Division Imperial Chemical Industries Limited. Mr. J. M. Wilson formerly of the College of Technology Liverpool has been appointed Prin- cipal Lecturer in Physical Chemistry at the Lough- borough College of Technology.PROGRAMME OF MEETINGS* OCTOBER 1963 TO JANUARY 1964 London Thursday October loth 1963 at 6 p.m. E. W. T. Steacie Memorial Lecture by Professor H. E. Gunning M.A. Ph.D. To be given in the Anatomy Lecture Theatre King’s College Strand w.c.2. Thursday October 24th at 2.15 p.m. Symposium on Peptide Chemistry. To be held in the Edward Lewis Lecture Theatre Middlesex Hospital Medical School Cleveland Street W. 1. (Details will be circulated to Fellows.) Thursday November 21st at 6 p.m. Meeting for the Reading of Original Papers. To be held in the Rooms of the Society Burlington House w.l. Thursday December 12th at 6 p.m. Liversidge Lecture “Some Contemporary Problems of Solid-state Chemistry,” by Professor J.S. Anderson Ph.D. F.R.S. To be given in the Lecture Theatre The Royal Institution 2 Albemarle Street w.l. Thursday January 23rd 1964 at 6 p.m. Tilden Lecture “Activated Molecules,” by Professor A. F. Trotman-Dickenson Ph.D. To be given in the Lecture Theatre School of Pharmacy 29-39 Bruns-wick Square W.C.l. [British Railways are offering concessionary fares (single fare plus one half for the return journey) for London meetings untii at least the end of 1963; a travel voucher for any meeting will be sent by the * Reprints of this programme can be obtained from the General Secretary The Chemical Society Burlington House London W.l. SEPTEMBER 1963 General Secretary on receipt of a stamped and addressed envelope.] Aberdeen Tuesday October 8th 1963 at 8 p.m. Discussion “School Chemistry and After.” Chair- man Professor G. M. Burnett Ph.D. D.Sc. Joint Meeting with the Royal Institute of Chemistry and the Society of Chemical Industry to be held in the Staff Common Room Marischal College. Thursday October 17th at 8 p.m. Lecture “What is Nucleophilicity?” by Dr. R. F. Hudson A.R.C.S. A.R.I.C. Joint Meeting with the University Chemistry Society to be held in the Chemistry Department The University. Thursday December Sth at 8 p.m. Lecture “Some New Natural Products Structural and Biosynthetic Studies,” 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 Medical Physics Lecture Theatre Marischal College.Aberystwyth (Joint Meetings with the University College of Wales Chemical Society to be held in the Edward Davies Chemical Laboratory.) Thursday October loth 1963 at 5 p.m. Lecture “Some Research in Washington,” by Dr. R. E. Kagarise. Thursday October 24th at 5 p.m. Lecture “Modern Thermochemistry,” by Professor H. D. Springall M.A. D.Phil. Thursday November 7th at 5 p.m. Lecture “Name and Number,” by Dr. R. B. Heslop M.Sc. F.R.I.C. Thursday November 21st at 5 p.m. Lecture “Optical Rotatory Power,” by Dr. S. F. Mason M.A. Thursday December Sth at 5 p.m. Lecture “Biosynthesis,” by Professor A. J. Birch D.Phil. F.R.S. Birmingham (Joint Meetings with the University Chemical Society to be held in the Chemistry Department The University.) Monday October 7th 1963 at 4.30 p.m.Lecture “The Reactions of Free Radicals with Nitric Oxide,” by Professor H. E. Gunning M.A. Ph.D. Friday November 15th at 4.30 p.m. Lecture “Some Unusual Electrophilic Aromatic Substitutions,” by Professor C. Eaborn D.Sc. F.R.I.C. Friday January 24th 1964 at 4.30 p.m. Lecture “Some Aspects of the Chemistry of Flames,” by Dr. T. M. Sugden M.A. F.R.S. Bristol (Joint Meetings with the Society of Chemical Industry and the Royal Institute of Chemistry to be held in the Department of Chemistry The University unless otherwise stated.) Thursday October 3rd 1963 at 6 p.m. Lecture “The Development of Alloys for High- temperature Service,” by Dr.R. A. Smith. Thursday October loth at 6.30 for 7 p.m. Lecture “The Principles and Chemistry of Colour Photography,” by Dr. R. A. Jeffreys F.R.I.C. To be given at Street Somerset. Wednesday October 16th at 7 p.m. Lecture “The Modern Techniques of Calendering P.V.C. Sheet,” by Mr. N. Stackhouse A.R.I.C. Joint Meeting with the Plastics Institute to be held in the Technical College Gloucester. Thursday October 31st at 6.30 p.m. Lecture “Opium,” by Professor A. R. Battersby D.Sc. Ph.D. Thursday November 7th at 6.30 p.m. Lecture “Taking a Look at Some Basic Concepts,” by Dr. H. J. T. Ellingham O.B.E. F.R.I.C. Thursday December 5th at 6.30 p.m. Lecture “Development of Severnside,” by Mr. J. Davidson B.Sc.Thursday January 9th 1964 at 6.30 p.m. Lecture “Recent Development in Collogen Re- search,” by Professor A. G. Ward O.B.E. M.A. Thursday January 30th at 6.30 p.m. Lecture “Recent Developments in Tyre Tech-nology,” by Mr. G. F. Morton B-Sc. A.1nst.P. Cambridge (Joint Meetings with the University Chemical Society to be held in the University Chemical Laboratory Lensfield Road.) Friday October 1 lth 1963 at 8.30 p.m. Lecture “The Nature of the Primary Process in Mercury-photosensitisation,” by Professor H. E. Gunning M.A. Ph.D. Friday October 25th at 8.30 p.m. Lecture “Nucleophilic Aromatic Substitution,” by Professor N. B. Chapman M.A. Ph.D. F.R.I.C. Friday November 22nd at 8.30 p.m. Lecture “Transition-metal Hydrides and the Base Behaviour of Some Transition-metal Complexes,” by Professor G.Wilkinson Ph.D.F.R.I.C. Cardiff (Meetings to be held in the Department of Chem- istry University College Cathays Park Cardiff.) Monday October 28th 1963 at 5 p.m. Lecture “Microcalorimetry of Living Processes,” by Dr. H. A. Skinner B.A. Monday November 11 th at 5 p.m. Lecture to be given by Dr. A. G. Maddock D.I.C. Dublin Wednesday October 30th 1963 at 5.30 p.m. Lecture “A Chemical Cornucopia,” by Dr. T. B. H. McMurry F.T.C.D. F.I.C.I. To be given in the Department of Chemistry University College. Friday November 22nd at 5.30 p.m. Lecture “Catalytic Reactions of Aromatic Mole- cules on Metals,” by Professor C. Kemball Sc.D. F.R.I.C. Joint Meeting with the Werner Society to be held in the Department of Chemistry Trinity College.Dundee (Meetings to be held in the Chemistry Department Queen’s College.) Tuesday November 5th 1963 at 5 p.m. Lecture “Structural Information from Electron- resonance Measurements,” by Dr. D. H. Whiffen M.A. Tuesday November 19th at 5 p.m. Lecture “Using Mutants to Elucidate Pathways of Biosynthesis,” by Professor C. H. Hassall Ph.D. F.R.I.C. Durham (Joint Meetings with the University Chemical Society to be held in the Science Laboratories South Road.) Monday October 14th 1963 at 5 p.m. Lecture “Determination of the Molecular Structure of a Globular Protein,” by Dr. H. C. Watson. Monday November 4th at 5 p.m. Lecture “Some New Developments in the Chem- istry of Diazonium Salts,” by Dr.J. M. Tedder M.A. Monday November 18th at 5 p.m. Lecture “Additions and Substitutions in Some Olefinic and Aromatic Systems,” by Professor P. B. D. de la Mare D.Sc. F.R.I.C. Monday November 25th at 5 p.m. Lecture “Some Aspects of the Chemistry of Flames,” by Dr. T. M. Sugden M.A. F.R.S. Tuesday December loth at 5 p.m. Lecture “The ‘Rare-gas Rule’ in Transition-metal Complexes,” by Professor D. P. Craig D.Sc. F.R.I.C. PROCI EDINGS Edinburgh Thursday October 24th 1963 at 7.30 p.m. Lecture “The Chemical Versatility of Triethyl Phosphite,” by Professor J. I. G. Cadogan Ph.D. F.R.I.C. Joint Meeting with the Royal Institute of Chemistry and the Society of Chemical Industry to be held in the Heriot-Watt College.Tuesday November 19th at 4.30 p.m. Lecture “Kinetic Theory of Gases Old and New,” by Professor P. Gray M.A. Ph.D. Joint Meeting with the University Chemical Society to be held in the Department of Chemistry The University. Thursday November 21st at 7.30 p.m. Lecture “Carbanions to Carbenes,” by Professor R. N. Haszeldine D.Sc. F.R.I.C. Joint Meeting with the Royal Institute of Chemistry and the Society of Chemical Industry to be held in the Herio t- Wat t College. Thursday December 12th at 7.30 p.m. Lecture to be given by Dr. D. S. Davies M.A. Joint Meeting with the Royal Institute of Chemistry and the Society of Chemical Industry to be held in the Heriot-Watt College. Tuesday January 14th 1964 at 4.30 p.m.Lecture to be given by Dr. M. C. Whiting. Joint Meeting with the University Chemical Society to be held in the Department of Chemistry The Univer- sity. Thursday January 16th at 7.30 p.m. Lecture “Hemicelluloses Gums and Pectic Sub- stances,” by Dr. G. 0. Aspinall F.R.I.C. 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 October 25th 1963 at 5.15 p.m. Lecture “The Synthesis of Polyenes,” by Professor B. C. L. Weedon Ph.D. D.Sc. F.R.I.C. Friday January 24th 1964 at 5.15 p.m. Tilden Lecture “A Glow in the Dark-The Rationale of Phosphorylation,” by Dr. V.M. Clark M.A. Glasgow Thursday October 17th 1963 at 4 p.m. Lecture “Metal-to-Metal Bonds in Inorganic Chem- istry,” by Professor R. S. Nyholm D.Sc. F.R.S. Joint Meeting with the Alchemist’s Club and The Andersonian Chemical Society to be held in the Chemistry Department The University. Thursday November 14th at 4p.m. Lecture “The Chemistry of Bacterial Cell Walls,” by SEPTEMBER 1963 Professor J. Baddiley D.Sc. F.R.S. Joint Meeting with The Andersonian Chemical Society to be held in the Chemistry Department The Royal College of Science and Technology. Wednesday December 4th at 3.30 p.m. Official Meeting and Symposium “Isotopes,” 50th Anniversary of the fist published use of the term “Isotope.” Contributions will include papers by Dr.J. A. Cranston Lord Fleck K.B.E. F.R.S. and Dr. A. Kent M.A. To be held at the Chemistry Department The University. Thursday January 30th 1964 at 4 p.m. Lecture “Electron Spin Resonance,” by Professor M. C. R. Symons D.Sc. F.R.I.C. Joint Meeting with The Andersonian Chemical Society to be held in the Chemistry Department The Royal College of Science and Technology. Hull (Joint Meetings with the University Students Chem- ical Society to be held at the Department of Chemistry The University unless otherwise stated.) Thursday October 17th 1963 at 7.30 p.m. Lecture “Aromatic Fluoro-compounds,” by Pro- fessor J. C. Tatlow Ph.D. F.R.I.C. Joint Meeting with the Royal Institute of Chemistry. Thursday November 21st at 4 p.m.Lecture “The Wittig Reaction,” by Dr. S. Trippett B.A. Thursday December Sth at 4 p.m. Lecture “Seeing Molecules with Microwaves,” by Dr. J. Sheridan M.A. Thursday January 16th 1964 at 4 p.m. Lecture “Magnetism and Stereochemistry of Transition-metal Complexes,” by Professor J. Lewis D.Sc. Ph.D. Keele Tuesday October 22nd 1963. Lecture “The Synthesis and Some Properties of Partially Synthetic Ribonucleases,” by Professor A. K. Hofmann Ph.D. To be given in the Depart- ment of Chemistry The University. Leeds (Meetings to be held in the Chemistry Lecture Theatre The University.) Tuesday October 8th 1963 at 6 p.m. Lecture “Reactions Associated with the Singlet and the Triplet State of Atomic Sulphur,” by Professor H.E. Gunning M.A. Ph.D. Thursday October 31st at 6 p.m. Lecture “The Photochemistry of Some Organic Charge-transfer Complexes,” by Dr. J. A. Barltrop M.A. Leicester (Joint Meetings with the University Chemical Society to be held in the Department of Chemistry The University.) Monday November 4th 1963 at 4.30 p.m. Lecture “Metal-to-Metal Bonds in Inorganic Chemistry,” by Professor R. S. Nyholm D.Sc. F.R.S. Monday November 18th at 4.30 p.m. Lecture “The Mode of Action of Tetraethyl-lead as an Anti-knock,” by Professor A. D. Walsh M.A. Ph.D. F.R.S.E. Monday January 13th 1964 at 4.30 p.m. Lecture “Some New Natural Products Structural and Biosynthetic Studies,” by Professor W. D. Ollis Ph.D. Liverpool (Joint Meetings with the University Chemical Society to be held in the Donnan Laboratories The Chemistry Department The University.) Thursday October 31st 1963 at 5 p.m.Lecture “Some Novel Cyclisation Reactions-New Chapters in Heterocyclic Chemistry,” by Professor D. H. Hey D.Sc. F.R.S. Thursday November 28th at 5 p.m. Lecture “Living Polymers,” by Professor M. Szwarc Ph.D. D.Sc. Thursday January 30th 1964 at 5 p.m. Lecture “Some Applications of Reaction Kinetics to Analytical Problems,” by Professor H. Irving M.A. D.Sc. F.R.I.C. Manchester (Meetings to be held in the Manchester College of Science and Technology unless otherwise stated.) Thursday October 17th 1963 at 6.30 p.m. Lecture “Transition-metal Hydrogen Bonds and the Protonation of Some Metal Complexes,” by Professor G.Wilkinson Ph.D. F.R.I.C. Friday November lst at 10 a.m. Symposium “Silicones,” Joint Meeting with the Society of Chemical Industry and the Royal Institute of Chemistry to be held in the Manchester Literary and Philosophical Society 36 George Street. Thursday November 14th at 6.30 p.m. Lecture “The Synthesis of Peptides,” by Dr. G. T. Young F.R.I.C. Thursday December 12th at 6.30 p.m. Lecture “Some Applications of Electron Spin Resonance to Chemistry,” by Professor H. C. Longuet-Higgins M.A. D.Phil. F.R.S. Thursday January 16th 1964 at 6.30 p.m. Lecture “Stereochemistry of Squalene Biosyn- thesis,” by Dr. G. J. Popjiik F.R.S. Thursday January 30th at 5 p.m. Lecture “Alkaloid Biosynthesis,” by Professor A.R. Battersby D.Sc. Ph.D. Joint Meeting with the Royal College of Advanced Technology Chemical Society to be held in the Royal College of Advanced Technology Salford. Newcastle-upon-T yne (Meetings to be held in the Chemistry Department The University.) Friday November 15th 1963 at 5.30 p.m. Bedson Club Lecture “The Journal of the Chemical Society Present and Future,” by Dr. R. S. Cahn M.A. F.R.I.C. Tuesday November 19th at 5.30 p.m. Official Meeting and Lecture “n-Complexes of Transition Metals-Some Recent Studies,” by Professor P. L. Pauson Ph.D. F.R.I.C. Friday November 29th at 6.30 p.m. Lecture “Exploring Surface Reactions on an Atomic Scale,” by Professor J. S. Anderson Ph.D. F.R.S. Joint Meeting with the Royal Institute of Chemistry.Friday December 13th at 5.30 p.m. Bedson Club Lecture “Natural Polyacetylenes,” by Sir Ewart Jones D.Sc. F.R.S. Friday January 24th 1964 at 5.30 p.m. Bedson Club Lecture to be given by Professor F. C. Tompkins D.Sc. F.R.S. Northern Ireland Thursday October 31st 1963 at 7.45 p.m. Lecture “Radioactivity in the Atmosphere,” by Dr. E. H. Willis. Joint Meeting with the Royal Institute of Chemistry and the Society of Chemical Industry to be held in the Department of Chemistry David Keir Building Queen’s University Belfast. North Wales Wednesday October 16th 1963 at 7.30 p.m. Lecture “Recent Advances in Acetylene Chem- istry,” by Professor R. A. Raphael Ph.D. F.R.S. Joint Meeting with the Royal Institute of Chemistry to be held in the Chemistry Department Denbigh- shire Technical College Wrexham.Thursday November 7th at 5.45 p.m. Lecture “Hydrogen Bonding,” by Dr. L. J. Bellamy. Joint Meeting with the University College of North Wales Chemical Society to be held in the Chemistry Department University College Bangor. Thursday January 30th 1964 at 5.45 p.m. Liversidge Lecture “Some Contemporary Problems of Solid-state Chemistry,” by Professor J. S. Anderson Ph.D. F.R.S. Joint Meeting with the PROCEEDINGS University College of North Wales Chemical Society to be held in the Chemistry Department University College Bangor. Nottingham (Joint Meetings with the University Chemical Society to be held in the Chemistry Department The University.) Tuesday October 22nd 1963 at 5 p.m.Lecture to be given by Dr. F. Sanger F.R.S. Tuesday November Sth at 5 p.m. Lecture to be given by Dr. L. E. Orgel M.A. F.R.S. Tuesday November 19th at 5 p.m. Lecture to be given by Dr. F. W. Gibbs. Tuesday December 3rd at 5 p.m. Lecture to be given by Professor F. C. Tompkins Ph.D. F.R.S. Tuesday January 28th 1964 at 5 p.m. Lecture “Stereochemistry of Squalene Biosyn- thesis,” by Dr. J. W. Cornforth. Oxford (Joint Meetings with the Alembic Club to be held in the Inorganic Chemistry Laboratory.) Tuesday October 22nd 1963 at 3.30 p.m. Lecture “The Synthesis of Biologically Active Peptides,” by Dr. R. A. Boissonnas. Monday November 4th at 3.30 p.m. Lecture “Miscibility and Immiscibility in Simple Fluids,’’ by Professor A.R. Rowlinson. Monday November 18th at 3.30 p.m. Lecture “Tracer Studies in Plants,” by Professor A. R. Battersby D.Sc. Ph.D. Monday November 25th at 3.30 p.m. Lecture “The Investigation of Surface Chemistry as an Atomic Scale of Resolution,” by Professor J. S. Anderson Ph.D. F.R.S. Reading Tuesday November 12th 1963 at 5.30 p.m. Lecture “Some Reactions of Substituted Cyclo- butadienes,” by Professor R. C. Cookson M.A. Ph.D. F.R.I.C. Joint Meeting with the Royal Insti- tute of Chemistry and the University Chemical Society to be held in the Large Chemistry Theatre The University. St. Andrews (Joint Meetings with the University Chemical Society to be held in the Chemistry Department St. Salvator’s College.) Thursday October 17th 1963 at 5.15 p.m.Lecture to be given by Professor J. I. G. Cadogan, Ph.D. F.R.I.C. Thursday October 31st at 5.15 p.m. Lecture “Some Aspect of Boron Chemistry,” by Dr. A. K. Holliday F.R.I.C. SEPTEMBER 1963 Thursday November 14th at 5.15 p.m. Lecture “The Simplest Chemical Reaction,” by Professor G. Porter F.R.I.C. F.R.S. Thursday November 21st at 5.15 p.m. Lecture “A Beery Chemist’s Discourses,” by Dr. J. 0. Harris F.R.I.C. Sheffield (Joint Meetings with the Royal Institute of Chem- istry and the University Student Chemical Society to be held in the Department of Chemistry The University.) Thursday November 14th at 4.30 p.m. Lecture “Boranes Alanes and Gallanes,” by Professor N.N. Greenwood Ph.D. F.R.I.C. Thursday January 23rd 1964 at 4.30 p.m. Lecture “Some Recent Work on Hydrogen Isotope Effects,” by Dr. Victor Gold. Thursday January 30th at 4.30 p.m. Lecture “Claudogenic Steroids,” by Dr. V. Petrow F.R.I.C. Southampton (Joint Meetings with the University Chemical Society to be held in the Chemistry Department The University unless otherwise stated. ) Monday October 14th 1963 at 5 p.m. Lecture “Triplet-state Reactions in the Gas Phase,” by Professor H. E. Gunning M.A. Ph.D. Friday November 8th at 5 p.m. Lecture “Some Aspects of Nuclear Magnetic Resonance,” by Professor R. E. Richards M.A. D.Phi1 F.R.S. Friday November 15th at 7 p.m. Lecture “Overcrowded Molecules,” by Professor C. A. Coulson Ph.D.D.Sc. F.R.S. Joint Meeting with the Portsmouth and District Chemical Society to be held in the Lecture Theatre H.9 The College of Technology Anglesea Road Portsmouth. Friday December 6th at 5 p.m. Lecture “Co-ordination Complexes,” by Professor J. Lewis D.Sc. F.R.I.C. Wednesday January 22nd 1964 at 7 p.m. Lecture “A Chemist at Sea,” by Dr. L. H. N. ADDITIONS TO Scientific research in British Universities and Colleges 1962-63. Issued by the Department of Scientific and Industrial Research and the British Council. Pp. 669. H.M.S.O. London. 1963. A short history of the Royal Gunpowder Factory at Waltham Abbey. W. H. Simmons. Pp. 113. Controllerate of Royal Ordnance Factories. Waltham Abbey. 1963. (Presented by the publisher.) Mass spectral correlations.F. W. McLafferty. (Ad- vances in Chemistry Series No. 40.) Pp. 117. American Chemical Society. Washington. 1963. 29 1 Cooper F.R.I.C. Joint Meeting with the Portsmouth and District Chemical Society to be held in the Department of Chemistry College of Technology Portsmouth. Swansea (Joint Meetings with the Student Chemical Society to be held in the Department of Chemistry Univer- sity College.) Monday October 14th 1963 at 4.30 p.m. Lecture “Magnetism and Inorganic Chemistry,” by Professor J. Lewis D.Sc. F.R.I.C. Monday October 21st at 4.30 p.m. Lecture “Science in Art and Archaeology,” by Dr. A. E. Werner. Monday November 11 th at 4.30 p.m. Lecture “Branched-chain Sugars,’’ by Professor W. G.Overend D.Sc. F.R.I.C. Monday December 2nd at 4.30 p.m. Lecture “Some Problems of Photochemistry and Reaction Kinetics Exposed by Kinetic Spectro- scopy,” by Professor R. G. W. Norrish Sc.D.. F.R.S. Tees-side (Joint Meetings with the Royal Institute of Cheni- istry and the Society of Chemical Industry.) Wednesday October 30th 1963 at 8 p.m. Lecture “Biological Nitrogen Fixation,” by Dr. E. R. Roberts. To be given at the Constantine College of Technology Middlesbrough. Wednesday November 27th at 8 p.m. Lecture “Recent Trends in Chemical Education,” by Mr. D. G. Chisman B.Sc. F.R.I.C. To be given at the Constantine College of Technology Middles- broug h . Thursday December 12th at 8 p.m. Lecture “Gibberellins and Plant Growth,” by Professor P.W. Brian D.Sc. F.R.S. To be given at the William Newton School Norton. Thursday January 9th 1964 at 8 pm. Lecture “Catalysis from the Standpoint of Solid-state Chemistry,” by Dr. F. s. Stone. To be given at the William Newton School Norton. THE LIBRARY Ultraviolet spectral data. Supplementary sheets dated October 31st 1962 (Lot 38). Pp. 55. American Petroleum Institute. Texas. 1962. Quantitative evaluation of substituent effects by elec- tronic spectroscopy. J. N. Murrell. Quantitative aspects of aromatic substitution. R. 0. C. Norman. Meldola Medal Lectures 1962. (Royal Institute of Chemistry Lectures 1963 No. 2.) Pp. 32. Royal Institute of Chem- istry. London. 1963. (Presented by the publisher.) Les rkactions chimiques dans les solvants et les sels fondus.G. Charlet and B. Trkmillen. Pp. 602. Gauthier- Villars. Paris. 1963. (Presented by Bureau Scientisque Ambassade de France ii Londres.) The nitrides and sulphides of uranium thorium and plutonium a review of present knowledge. R. M. Dell and M. Allbutt. (United Kingdom Atomic Energy Authority A.E.R.E. R 4253.) Pp.48. A.E.R.E. Harwell. 1963. Configurational statistics of polymeric chains. M. V. Volkenstein. (High Polymers Vol. 17.) Pp. 562. Inter- science Publ. Inc. New York. 1963. Polymers of heavy metals with dialkylphosphoric acids. C. J. Hardy and J. M. Fletcher. (United Kingdom Atomic Energy Authority. A.E.R.E. R 4281.) Pp. 4. A.E.R.E. Hanvell. 1963. Polystyrene materials a code of practice.Pp. 44. British Plastics Federation. London. 1963. (Presented by the publisher.) Technique of organic chemistry. Edited by Arnold Weissberger. Vol. 8. Investigation of rates and mechan- isms of reactions. Edited by S. L. Friess E. S. LRwis and A. Weissberger. Part 2. 2nd edn. Pp. 703-1582. Inter-science Publ. Inc. New York. 1582. Chemical thermodynamic properties of hydrocarbons and related substances properties of 100 linear alkane thiols sulfides and symmetrical disulfides in the ideal gas state from 0" to 1,OOO" K. D. W. Scott and J. P. McCullough. (Bureau of Mines-Bulletin 595.) Pp. 68. U.S. Government Printing Office. Washington. 1961. Steroid reactions an outline for organic chemists. Edited by C. Djerassi. Pp. 657. Holden-Day.San Francisco. 1963. (Presented by the publisher.) Living molecules. J. N. Davidson. 12th Dalton Lecture. (Royal Institute of Chemistry Lectures-1963 No. 1.) Pp. 17. Royal Institute of Chemistry. London. 1963. (Presented by the publisher.) Standard methods of chemical analysis. Edited by F. J. Welcher. Vols. 2A and B. 6th edn. Pp. 2613. Van Nostrand. New York. 1963. Treatise on analytical chemistry. Edited by I. M. Kolthoff J. Elving and E. B. Sandell. Part 11. Vol. 8. Pp. 556. Interscience Publ. Inc. New York. 1963. Methods of analysis of essential oils. M. Goriaev and I. Pliva. (In Russian.) Pp. 751. Akademia Nauk Kazakhskoi S.S.R. Alma-Ata. 1962. (Presented by the publisher.) Deterrnination of uranium and thorium. Handbook of chemical methods for their determination.Pp. 43. H.M.S.O. London. 1963. (Presented by the National Chemical Laboratory.) Agriculture and some of its chemical problems. E. G. Cox. 5th P. F. Frankland Memorial Lecture. (Royal Institute of Chemistry Lectures 1963 No. 3.) Pp. 12. R.I.C. London. 1963. (Presented by the publisher.) Some cosmochemical problems. H. C. Urey. Edited and sponsored by Mu Chapter of Phi Lambda Epsilon Pennsylvania State University. (37th Annual Priestley Lecture.) Pp. 181. Pennsylvania State University. Penn- sylvania. 1963. The Oxoid manual of culture media including in- gredients and other laboratory services. 2nd edn. 0x0 Ltd. London. 1962. (Presented by the Librarian 0x0 Technical Library.) Industrial hygiene and toxicology.Edited. by F. A. Patty. Vol. 2. 2nd edn. Pp. 831-2377. Interscience Publ. Inc. New York. 1962. Applications of computers to nuclear and radio-chemistry Proceedings of a symposium Gatlinburg Tennessee 1962. Edited by G. D. O'Kelley. Organised by the United States National Research Council Sub- committee on Radiochemistry and sponsored by the United States Atomic Energy Commission. (Nuclear Sciences Series NAS-NB 3107.) Pp. 314. U.S.Atomic Energy Commission. Washington. 1963. (Presented by the publisher.) IX Colloquium Spectroscopicum Internationale held in Lyon 1961. Issued by the Groupement pour 1'Avance-ment des MCthodes Spectrographiques. Muray-Print. Paris. 1962. Nonstoicheiometric compounds. A symposium spon- sored by the Division of Inorganic Chemistry at the 141st Meeting of the American Chemical Society Washington 1962.(Advances in Chemistry Series No. 39.) Pp. 253. American Chemical Society. Washington. 1963. (Pre- sented by the publisher.) Nitro paraffins. Proceedings of a symposium held at Furdue University i961. Sponsored by the Office of Naval Research and the Purdue Department of Chem-istry. Edited by H. Feuer. (Tetrahedron 1963 Vol. 19 Supplement 1.) Pp. 248. Pergamon Press. Oxford. 1963. Petrochemicals and petroleum refining. Papers pre- sented during meetings of the American Institute of Chemical Engineers in Mexico City and Tulsa. Edited by H. L. Hays and J. W. Davidson. (Chemical Engineering Progress Symposium Series 1961 57 No. 34.) Pp.94. A.1.Ch.E. New York. 1961. Pollution and environmental health. Papers presented at a symposium held under the auspices of the American Institute of Chemical Engineers Pollution Control Engineering Committee in Washington 1960. Edited by W. L. Faith. Pp. 73. (Chemical Engineering Progress Symposium Series 1961 57 No. 35.) A.1.Ch.E. New York. 1961. Applied mathematics in chemical engineering. (Chem- ical Engineering Progress Symposium Series 1962 58, No. 37.) Pp. 106. A.1.Ch.E. New York. 1962. Fluidization. Papers presented at a symposium held in New York 1961 during the 44th Annual Meeting of the American Institute of Chemical Engineers. Edited by F. A. Zenz. (Chemical Engineering Progress Symposium Series 1962 58 No. 38.). Pp. 122.A.I.Ch.E.New York. 1962. Techniques of polymer science comprising papers (with discussions) read at a symposium organised by the Plastics and Polymer Group of the Society of Chemical Industry 1962 in London. (S.C.I. Monograph No. 17.) Pp. 319. Society of Chemical Industry. London. 1963. (Presented by the S.C.I.) Second conference on the chemistry and use of organo- phosphorus compounds held in Kazan 1959. Introduced by A. Y. Arbuzov works of the chemical section translated by the United States Office of Technical Services. 6 Vols. Pp. 1155. U.S. Dept. of Commerce O.T.S. Washington. 1962. Chemistry of coal utilization supplementary volume. Edited by H. H. Lowry and prepared by the Committee on Chemistry of Coal Division of Chemistry and Chem- ical Technology National Academy of Sciences-National Research Council.Pp.1142. J. Wiley and Sons. London. 1963. Lubricating and allied oils. E. A. Evans. 4th edn. Pp. 234. Chapman and Hall. London. 1963. (Presented by the author.) American Society for Testing and Materials. Proceed- ings. Vol. 62.1962. Pp.1336.1963 A.S.T.M. Philadelphia. 1963. NEW JOURNALS Biopolymers from 1963,l. Journal of Gas Chromatography from 1963 1. Steroids from 1963,l.

ISSN:0369-8718    

DOI:10.1039/PS9630000253

出版商:RSC    

年代:1963

数据来源: RSC