PROCEEDINGS OF THE CHEMICAL SOCIETY APRIL 1964 ‘(EDUCATION IN CHEMISTRY ”* By J. M. BLATCHLY (THECOLLEGE SUSSEX) EASTBOURNE STATISTICIANS, the soothsayers of the age have predicted that if scientific journals proliferate at the present rate there will be over a million by the end of the century. Whether or not this is so the latest addition to the ranks Education in Chemistry with its Vol. 1 No. 1 dated January 1964 obviously fills a gap in the present range of literature. This review will aim to discuss the timing aims of and demand for the new Royal Institute of Chemistry venture but perhaps one com- plaint can be registered at the outset concerning the presentation. The style of the cover the paper printing and illustrations the reviewer feels to be unimaginative and old-fashioned and it is very much to be hoped that the first year will find the journal so well established that the financial problems of producing a really attrac- tive format will not be insurmountable.It did occur to one chemist asked for an opinion on the appearance of the first issue that the editorial advisory board might be indulging in a cunning ruse to catch reactionary chemistry teachers un- awares by putting their very new wine into old bottles. It is generally agreed that chemistry teaching is coming in for drastic revision at the elementary stages for the first time for over forty years and this is surely no exaggeration. A colleague who sat Chemistry in School Certificate in 1919 assures me that he has detected no fundamental change in the requirements of the syllabus since then.He could only instance the extraction of aluminium and the Solvay process as innova- tions and the exclusion of the Brin process the Parkes process and Dulong and Petit’s Law among the piecemeal changes. In the June of the year in which he set out on the road to becoming a teacher of the subject the first number of the School Science Review appeared. A quick glance at this slender volume shows so much of the same sentiment as the first edition of its much * Published quarterly by the Royal Institute of Chemistry London price 40s./annum “Education in Chemistry” is a new journal devoted to the improvement of chemical education at all levels.It has been launched to provide a forum for discussion of the new thinking in chemical education that is being developed by university and school teachers in this country and overseas. Main articles will be presented in ways that it is hoped will stimulate teachers to improve their own presentation of the subject. Articles by practising teachers will include expositions of developing areas of chemistry and helpful suggestions on the teaching of the subject. Current activities in Great Britain and overseas will be surveyed and there will also be critical reviews of text books film notes and accounts of apparatus and equipment including visual and other teaching aids. 101 younger relation that one gains the impression that time has moved little since then.The same burning questions are discussed should Physics and Chemistry be combined ? The recent forma- tion of the Neglect of Science Committee (was the Chairman called Minister for Science?); the Association of Science Masters report “Science for All” (the central aim of the Nuffield Project is thus expressed); the Headmasters in agree- ment that all boys should study Science to the age of sixteen (why was this not enforced?); Research in schools ; Advances in Chemistry including adequate details for the preparation of acetaldehyde from acetylene by the industrial method a key experiment little demonstrated in schools until recently. The present problem of reshaping the presenta- tion of the elementary stages of the subject is now being tackled in earnest not only nationally but internationally as is shown by the interesting World View section in the new journal com- menting on the changing state of teaching abroad.The United States with C.B.A. and CHEM study lead our Nuffield Foundation Science Teaching Project by less than five years and it is clear that things are well under way now that Nuffield Project teaching material data books and guides will be available very soon. The various movements have much in common in a fresh mounting of the essential facts on a systematic framework of atomic and molecular structure and energy considerations each step based where possible on verification by experiment. The British Committee on Chem- ical Education founded in 1962 now has a medium for the publication of articles concern- ing all new developments in the teaching of the subject in the new journal.It might be instructive to ask why this in particular should be the time for so much objec- tive criticism of the tired corpus of the chemistry master’s stock-in-trade. No-one will deny that this is necessary but why must the upheaval be so sudden and so dramatic? Why has there not been a steady evolution of better methods and changes of emphasis? This is a time of wide- spread national self-consciousness but dissatis- faction with science teaching is made more pointed by several factors. The material diffi- culties of poor laboratories and equipment can PROCEEDINGS no longer be used as excuse for inadequacy for although some overcrowding remains great im- provements have been made in the last ten years.Ninety-six per cent of public schools,1 91 % of direct grant schools and 76% of maintained grammar schools now have modernised or post- war laboratories; the excellence of the first two figures is mainly due to the foresight and financial assistance of the firms subscribing to the Industrial Fund for the Advancement of Science. The increased competition for existing places in further education particularly in uni- versities and the creation of new universities have certainly helped to encourage a new look at courses preparing for further education and a laudable fresh start on syllabuses at the newer universities.Professor Eaborn’s article on “Chemistry in the University of Sussex” makes it quite clear that the best course that can be devised without prejudice or conservatism awaits the intending student at Sussex. This should be only the first of many articles dealing with each of the university departments old and new so that when advising candidates on their choices there need be less vague speculation based on the reputations gained years before. The applied science problem,2 and the urgent need for a change in the image and status of the techno- logist in the structure of our society makes the thinking schoolmaster realise his inadequacy to help with the problem as he would wish; by the nature of things and perhaps this should not be so he will be a pure scientist by training.Here is another field in which Education in Chemistry can contribute valuably. In addition to the questioning of approach the teaching problem is being examined from many other angles. Far from being concerned with evolving new methods of presenting formal courses in the subject some are anxious to make quite different changes. A very relevant scheme is the Structure and Properties of Matter amal- gamation of basic Physics and Chemistry pro-posed anew for schools by Spice of Winchester and already in use at Sussex. There is clearly much to be gained by adopting this suggestion and the saving of time and avoidance of overlap (or underlap) and confusion may bring it into the schools at last.Others want applied science taught in schools but can one apply what one Advisory Centre for Education “Where” supplement Report on the Public Schools. Oxford University Department of Education survey “Technology and the Sixth Form Boy 1963.” APRIL1964 103 does not know? This innovation together with the assertion that no formal science should be taught below the sixth form is the view of the writers of the Bow Group report “Strategy for Schools.” There is a great danger in the attrac- tive idea that topically interesting science can usefully be taught before a formal course. Early discussion of ideas of modern physics plastics and petrochemicals can have little depth yet some of the latest new Ordinary Level syllabus proposals contain a disquieting proportion of these topics added to a tidied framework of the newer approach.In “Strategy for Schools” and in other places teachers are continually being accused of teach- ing only the examination syllabus and this is perhaps scarcely fair. Considering how seldom examination boards review the subject matter they aim to test the people teaching the subject have gone to endless lengths to vary the approach and content of their courses. One has only to cite the work of men like Van Praagh (the Heuristic method) and Peacocke (Radiochem- istry) who have devoted an immense amount of time and energy to the development in schools of topics never mentioned in syllabuses and of a great many more whose no less valuable contributions to the broader approach go un-recorded.It might be fairer to blame the examination boards for not commissioning more frequent reappraisals of the syllabus and the types of questions set; the fact that they do not do this sufficiently often is made patently obvious by the inclusion of such freaks as nitrogen per- oxide and Avogadro’s Law in one current Ordinary Level syllabus. So too we might look to the universities to recommend changes as strongly as is necessary at any rate in the Advanced Level syllabus if they feel that the candidates they take are getting the wrong training at school. If the few who are in a position to do something about bringing in changes are active in this way constant evolution of teaching method and official requirement must in future prevent a repetition of the present period of total reorientation and resultant confusion.The confusion will obviously resolve into a viable pattern of the new order in a few years and no arguments against change must be allowed to prevent the essential break with the old but the magnitude of the difficulties in which teachers and taught will find themselves must be stated in fairness to some whose work and university candidature may well come in for hard criticism in the interim. It is obviously true that many foreseeing the need for reorientation have been slowly accommodating to the new approach helped by more than average ability interest or youth (a ten-year old degree may be little help).The 1961 Science Masters Association “Science and Education” report and syllabus drafts were good guides in this and some further help has been given in the one-day courses in the teaching of each of the three branches of the subject given under S.M.A. (now Association for Science Education) and Royal Institute of Chemistry auspices in universities up and down the country. The longer out of university and the further out of touch and away from the centre of current development the more difficult it is going to be for men to carry conviction in the new approach to their pupils and here the vital business of re- training practically the whole profession brings the need for Education in Chemistry sharply into focus. The first issue contains special articles accurately aimed at this objective and tackles several of the most urgent new basic concepts (new at school level).Simple thermochemical cycles are well and systematically treated and combined with an object lesson in the necessity for complete energetic explanations of chemical phenomena. How useful the Nuffield data books will be in this type of work. Three more articles deal with structural chemistry with full instruc- tions for making teaching models and one of these (“Chemical Bonds crystals and lattices”) does start from first principles. Articles like this should probably rate first priority at present so that more senior teachers may quickly be helped to acquaint themselves with the new feel and look of the work required of them.The restraint of the editors in keeping articles fairly elementary is admirable; the time for elaboration will come later. It is sometimes hard to realise that the schoolmaster needs a far greater time to absorb new material than the specialist for the reason that he teaches such a vast range of topics and returns too seldom to the new concept for it to become part of his chemical thinking for some years. The only really effective solution would be very drastic compulsory one-week courses for non-specialists teaching to Ordinary Level held during term. But while the new journal keeps such realistic policies as this it will be doing a great service to the majority and there are more than enough sources already of specialist articles for the advanced minority.The book and film reviews are usefully detailed and will be most helpful when new texts are to be chosen. The expense of buying new- style textbooks will be enormous and perhaps we may look to the reviewers for more than usually brutal assessments of claims that books have been revised and brought up to date or written to cover the new approach. In recent years there has been an increased movement away from too great or too early specialisation. To this end young scientists are rightly encouraged to continue the study of their own or other languages in the Sixth form or possibly to take courses in History or Philo-sophy sometimes for as much as one third of their time. Likewise Arts sixth formers continue Science but the difficulties of planning suitable courses particularly in Physical Science often results in frustration for masters and pupils.This is a situation in which for once there is no syllabus to guide no examination to spur on the by now completely exam-conscious boy who anyway probably has an antipathy to the subject he never understood and thought to have left behind finally at fifteen. Here the experience of the gifted few who have really made a success of such a course would make the basis of a most interesting series of articles for the future. At the opposite end of the scale of specialisa- tion the journal mentions the Royal Society Committee for Scientific Research in Schools. The benefits of having original work being done with the co-operation of senior pupils cannot be over-estimated and it would be most interesting PROCEEDINGS to see published more detailed assessments of the success of the many school projects now in pro- gress.There must be many relatively simple pieces of work left on one side in all fields of research for reasons of time and the essential pursuit of the main aims of the work and schools would welcome the chance to take these on. Could not small practical problems be offered through this journal? They would not all need special facilities and might lead to some- thing bigger. The results of the present changes are not difficult to predict. If we are enabled as a cor- respondent puts it so poignantly in a letter to the Editor to help “the student acquire a viable general appreciation of Chemistry in less time than it took his teacher to reach the same level,’’ we will all have learnt a splendid lesson in economy of thought and in discipline.At any rate we shall mind less when questions are trans- ferred word for word from Tripos Papers (sic) to Scholarship papers ten years later as faster coverage becomes possible when a better balance between principles and facts emerges. What is more when the school scientist has put his house in order he will hope that the universities old as well as new will warmly greet the change in the men they receive. Reading lists recently sent to boys by a Cambridge college include a most depressing selection of out of date texts and too often one hears particularly from brighter former pupils that the subject has become for them dull and uninspiring.This cannot be en- tirely the fault of the student. Here is clearly the cue for all those teaching Chemistry to burn their notes and start afresh. Let us hope that Education in Chemistry will shame us all into accepting this radical advice in the months ahead. THE GROUP DISPLACEMENT LAW* By JOHNA. CRANSTON, D.Sc. LL.D. F.R.I.C. IT was my good fortune in 1912 to be permitted to join the Research School of this Chemistry Depart- ment and by the time I settled down I found that I was to have a ringside seat at the spectacle of the greatest revolution in history of the development of chemical principles viz.that presented by the con- cepts of isotopes and atomic numbers. Let me remind you of the position of chemical theory at that time. During the preceding half- century as indeed still the navigational chart by which students of Chemistry steered their way through the intracacies of their subject was the Periodic Table. (Let me divert for one moment to note that this year 1963 is the centenary of that original but partial and ill-recognised Law of Octaves put forward by Newlands.) Mendeleev’s * Delivered before The Society at the University of Glasgow on December 4th 1963 at the meeting held to com- memorate the fiftieth anniversary of the first published use of the term “Isotopes”. APRIL1964 Law that the properties of the elements were a periodic function of their atomic weights was of such obvious significance that anomalies could not be tolerated without profound investigation.An in-spiration was thus provided for the most exacting determinations of atomic weights and the early work of men like Stas of Belgium and the later work of Richards in America and of Honigschmidt in Vienna reached the pinnacle of achievement in pre- cision by chemical methods. Volumes could be written on the work done on one anomaly alone-to see if the atomic weight of iodine was not really greater than that of tellurium. All to no avail and the existence of these anomalies together with the intrusion of the rare-earth elements meant that Soddy could say in 1910 that “there was no hint whatever of the meaning of the Periodic Classification and that from the theoretical standpoint it remained a verit- able cryptogram crying out to be deciphered”.At that time the total number of elements between hydrogen and uranium was unknown and it is ap- propriate to refer to a letter published in Nature on July 20th 1911 by van der Broek drawing attention to the fact that for the lighter elements except hydrogen when arranged in the order of increasing atomic weights the average increment in atomic weight is two. For example the 20th element cal- cium has an atomic weight of 40. If this average is maintained then uranium with an atomic weight of 240 would be the 120th element. This might be realised if more rare earths were to be discovered and if the numerous radio-elements were regarded as separate elements.This speculation is fanciful but the idea of numbering the elements gives some slight claim for giving van der Broek the credit for the concept of atomic numbers. I have emphasised the Periodic Classification because of the important part it was still to play and because it was natural that chemists with their pre- occupation with it would use it to accommodate their discoveries in radioactivity. That we in this Department were much concerned with it the minutes of the meetings of the Honourable Company of Alchemists will testify. However before the close of the 19th Century new and powerful tools became available to tackle the problem through the discoveries in successive years of X-rays radioactivity and the electron.The atomic nature of matter from being a hypothesis (which Chemistry according to Ostwald could do quite satisfactorily without) became a reality amen- able to direct experiment; and work focussed on the structure of the atom was carried out in many diverse fields of science. PROCEEDINGS To remind you how diverse was this attack I have Speculation on atomic number (van der Broek). listed nine of these fields Quantum theory and spectra (Bohr). Mineralogy-Helium in ores (Ramsay) ; Pleo-Characteristic X-rays (Barkla). chroic halos in mica (Joly). Positive rays (J. J. Thomson). X-Ray frequency (Moseley). a-particles-Rectilinear path and “range” (Bragg).Chemical evidence of non-separability (McCoy a-particles and “single scattering” (the Rutherford and Ross (1907); Soddy and Marckw&d(l910k school). Fleck (191 1-13). Group Displacement Law). TABLE1. Some Papers published in 1913 Date Author Journal Substance January J. J. Thomson Proc. Roy. Soc. Positive rays-neon-22. Jan. 23 Fleck Proc. Chem. SOC. Chemical nature of nine jl-emitters (2nd Paper). Jan. 31 Russell Chemical News Adds imperfect p-ray rule to Soddy’s 1911 a-ray rule. Feb. 15 Fajans Phys. Zeit. Gives accurate Group Displacement Law based on electrochemical evidence but equates radio- active changes to valency changes disproved by Fleck (thorium and uranous salts). Feb. 28 Soddy Chemical News The complete Group Displacement Law.Soddy Jahr Radioactivitat As above but showing that unit differences of intra-atomic charge characterise successive places in the Periodic Table. Jan. 15 onwards von Hevesy and Paneth Phys. Zeit. and Monatsh. Electrochemical behaviour of radioelements. Valency. Adsorption. Use of radioelements as “indicators.” May 15 Fleck J. Chem. SOC. Final paper on the chemistry of the p-emitters. July Bohr Phil. Mag. Quantum ideas and atomic structure (as far as behaviour of electrons is concerned). Spectrum of hydrogen. July 20 van der Broek Nature Scattering. Charge not proportional to atomic weight but to the ordinal number of the element. Electrons in nucleus. Aug.-Sept . Aston Report Brit. Assoc. Preliminary account of attempts to separate neon from meta-neon.By fractionation (none); by diffusion (slight indications). Aug.-Sept. Soddy Report Brit. Assoc. Periodic Table and Atomic number (as above). September Bohr Phil. Mag. Systems of 1 2 3 and 4 electrons. Quotes Dis- placement Law and refers to van der Broek (p-rays come from nucleus). Dec. 4 Soddy Nature Word “isotope” introduced and idea of atomic number developed. Dec. 11 Rut herford Nature Supports van der Broek‘s idea of atomic number (jl-rays partly from external electrons?). Refers to Moseley’s paper. December Moseley Phil. Mag. Wavelengths of X-rays from 10 elements (Ca-Zn). Atomic numbers. December Bohr Phil. Mag. Develops idea of stationary States. Spectroscopy. Molecules. TABLE2. Researches of Dr. A. Fleck 1911-1 913 Radioelement Period of half-lge Iden tical chemically wit ti Radioactinium 19.5 d.Th Uranium X 24.6 d. Th Thorium B 10.6 hr Pb Actinium B 36.1 min. Pb Radium B 26.8 min. Pb Mesothorium TI 6.2 hr.. Ac Radium C 19.5 min. Bi Actinium C 2.5 min. Bi Thorium C 60.0 min. Bi Radium E 5.0 d. Bi Thorium D 3.1 min. T1 (unlike Ra D) Actinium D 4-71rnin. T1 (unlike Ra D) Radium A 3.0 min. Polonium APRIL1964 I will not now deal with these individually except to refer to the non-separability of radium and meso- thorium. For Soddy in 1910 using the powerful means that radioactive methods of measurement provide to detect the least change in the concentra- tion of a pair of active elements and failing to get any such change became from that date convinced of the phenomenon of chemical identity.The researches in the fields listed above are not at all in chronological order but the sequence of some papers published in the amazing year of 1913 is shown in Table 1. It was on January 23rd that Fleck’s paper on the chemical nature of nine p-emitters was read to the Chemical Society (Table 2). With this information Soddy was able to place the whole of the three radio- active series accurately in the Periodic Table (Figure); and to extend his 1911 a-ray rule to cover p-ray changes. The complete Group Displacement Law thus showed that the emission of an a-particle causes a shift of two places to the left in the Periodic Table whereas the loss of a p-particle causes a shift of one place to the right.Moreover by placing the Periodic Table for the last 12 elements in the y-axis of atomic mass and the x-axis of charge Soddy showed clearly in his papers to Jahr Radioactivitat and to the British Association that successive places in the Periodic Table correspond with integral differences of charge on the nucleus of the atom. This lent sup- port to van der Broek’s concept of atomic number. The spectacular advances by physicists summarised in papers by Rutherford (Phil. Mag. March 1914) and by Moseley (Phil.Mag. April 1914) enabled the concept of atomic numbers to be extended throughout the whole Periodic Table; and it is in- teresting that both papers quoted the Group Displacement Law in support of this concept.If it were worthwhile to debate the question of priority in the claims of physicists and chemists for the introduction of the concepts of isotopes and atomic numbers it is clear from the list of papers that the claims for the chemists is very strong. But I do not think the debate is worthwhile. It is another matter however to ignore the contributions of the chemists entirely. It is unfortunate that Soddy the most generous of men in ascribing credit to others for their work should see in his later years how his own contributions became ignored and it is a tragedy that he himself should have become so bitter about it. I think I can see two reasons why the con- tributions by chemists in this field have come to be overlooked.Firstly the teacher of chemistry nowadays must realise the enormous extent of the syllabus that he has to cover in a limited time; and this circumstance alone can justify him in short-circuiting all accounts of the vast experimental work that has been done to establish the structure of the atom. For by taking for granted a picture of the atom-hydrogen one proton with one planetary electron helium two and so on-then in a perfectly rational way the funda- mental laws of chemistry the concepts of valency the reactivities of the various elements and the ionic hypothesis all tumble out of the picture. But as chemists let us not forget the work of the great chemists of the past. If we are teachers let us not put the cart before the horse as badly as the examiner who asked his students to show that the Group Displacement Law follows from the electrical structures of the atoms concerned because as we have seen the Group Displacement Law is one of the important pillars on which these modern concepts rest.The second reason that contributes to the chemical work being overlooked lies in the fact that the word isotope is widely used nowadays in scientific literature without regard to its specific meaning. The word con- notes a relationship between two or more kinds of atoms which differ in some respects. It should not be used simply to denote one kind of atom-one nuclide. Thus when we read that natural fluorine contains me isotope we know what the author means although the phrase is etymologically un- sound.It is as though the compiler of an electoral register described a bachelor living alone in a flat as a husband (unmarried). On occasion this careless practice can be quite misleading. Dr. Crawford tells me that in our Annual Reports a reference to work on “The Separation of Radium Isotopes” actually refers to the separation of three elements of the radium disintegration series. We are celebrating today-not so much the jubilee of the concept of isotopes but the jubilee of the introduction of a word embodying a concept and founded on the work over several years of many chemists a word which crowned these efforts when the final work by Fleck enabled the results to be incorporated in the Periodic Table. If there is any concept whose jubilee year is this one it is the very closely related one of atomic number.And we have seen that the Group Displace- ment Law shows very clearly that unit difference of intra-atomic charge characterises the successive places in the Periodic Table. PROCEEDINGS COMMUNICATIONS Alkali-metal Derivatives of Dimethyl Sulphoxide By A. LEDWITH and N. MCFARLANE* COREYand CHAYAKOWSKI~ have shown that sodium in DMSO shows an intense absorption at 272 mp hydride reacts readily with dimethyl sulphoxide (E = 40,000)with a shoulder at 330 tnp (E = 16,000). (DMSO) producing sodium dimsyl which is a very By using the latter absorption the equilibrium shown useful reagent for the estimation of the strength of in reaction 1 has been studied spectrophoto-weak acids in DMS0.2,3 The enhanced basic strength metrically and at 25" with [KOBut] h-5 x lo-% of potassium t-butoxide when dissolved in DMSO Kl = 1.5 & 0-5 x lo-'.has been extensively characterised* and may be due This result implies that the acidity of ButoH is in part to an equilibrium involving dimsyl ion (I) as approximately 7 x 10s times that of DMSO whereas shown in eqn. 1. Steiner and Gilbert3 recently reported a value of 7 x lo3. The latter value was obtained from measure- K, K+ -0But + CH3.S0.CH3+ Kt -CH,.SO-CH (I) + BdOH (1) ments of equilibria involving K+-CH,.SO.CH,, I ButOH and triphenylmethane and in order to .1 clarify the discrepancy between the present result Ph2C(OH)CH2-SO*CH and that of Steiner and Gilbert3 we have studied the (11) equilibria shown in eqns.1-3. Water and oxygen K2 K+-CH2.S0.CH3 + Ph3CHF' K'Ph3C-+ CH3.SO*CH3 (2) were rigorously excluded from the reaction system. The main absorption maximum of triphenylmethyl K3 K+OBut+ Ph3CH+ K+Ph3C-+ ButOH . . . (3) occurs at 500 mp (E = 44,000)(see also ref. 2) independent of whether the ion was generated from Solutions of KOBut in DMSO react quantitatively KOBut-DMSO or K-DMSO. In addition by keep-with benzophenone to yield the P-hydroxysul-ing [Ph3CH] = 2 x 10-5~ and varying [KOBut] phoxide (11) and this confirms the rapid equilibrium from to 10-3~it was found that the spectra between base and solvent in these systems. showed an isosbestic point at 390 mp with an ab- It is now reported that sodium dimsyl can also be sorbance of 0.4,confirming that a true equilibrium conveniently prepared by direct reaction of the metal exists.Experimentally it was found that K3 = 1-2 with DMSO. Potassium dimsyl can be obtained x and hence K c=8 x lo3. Thus the acidity similarly but the reaction is violent and is best of triphenylmethane is approximately 8 x lo3 times carried out in vucuo. Solutions of sodium and potas- that of DMSO in fair agreement with the value sium dimsyl so prepared are readily characterised by (13 x lo3) reported by Steiner and Gilbert3 but the the quantitative reaction with benzophenone to acidity of ButOH is now found to be 830 times that give (31). of triphenylmethane whereas Steiner and Gilbert3 During the reaction between sodium and DMSO suggest that triphenylmethane and t-butyl alcohol the gas evolved is a mixture of hydrogen and di- have comparable acidities when potassium is the methyl sulphide with an essentially constant com- gegenion but apparently different acidities when position (62% H2 38% Me$).However the total sodium is the gegenion. The reasons for these gas yield is quantitative when based on the amount discrepancies are not yet obvious. of sodium consumed. The formation of dimethyl The original McEwen scale5 of acidities for weak sulphide indicates that other reduction products of acids gave pK values of approximately 18 and 33 DMSO (presumably water or sodium hydroxide) for t-butyl alcohol and triphenylmethane respec- must also be formed in these reactions.Consequently tively. However it is clear from the present work and solutions of dimsyl reagents prepared in this manner from the results reported by Steiner and Gilbert3 need to be filtered from insoluble hydroxides and that these relative acidities are meaningless when rigorously outgassed (to remove dissolved dimethyl dimethyl sulphoxide is used as solvent and reference sulphide) before use. acid. Under high-vacuum conditions potassium dimsyl (Received. December 3 1 st 1963.) * Donnan Laboratories. Universitv of Liveroool. Corey and Chayakowski J. Amir. Chem. Soc. 1962 84 866. Price and Whiting Chem. arid Ind. 1963 775. Steiner and Gilbert J. Amer. Chem. SOC.,1963 85 3054. Cf. Stewart O'Donnell Cram and Rickborn Tetrahedron 1962,18,917; Cram Kingsbury and Rickborn J.Amer. Chem. Soc. 1961,83,3688; Bank Rowe and Schriesheim ibid.,1963,85,2115; Russell and Becker ibid. 1963,85,3406. McEwen J. Amer. Chem. Soc. 1936,58 1124. APRIL1964 109 The Kinetics of Triplet-state Relaxation A Correction B. STEVENSand M. S. WALKER* INour preliminary communication1 a solution of the equations for triplet-state relaxation was based on the assumption that -dPA]/dt = -d[aQ]/dt is re- quired by the condition that -d(PQ]/pA](dt = dkTldt = 0. Dr. Francis Wilkinson has kindly pointed out to us that in fact the observation of an exponential decay requires that = -dlr~[~Q]/dt= -dl~~[~A]/dt kT and elimination of pQ]/pA] from the appropriate expressions leads to a quadratic equation for kT. If however the optical density of the impurity Q is sufficiently small that the quenching process 2 may be regarded as the only source of 3Q then the condition of exponential decay requires that * Department of Chemistry The University Sheffield 10.Stevens and Walker Proc. Chem. SOC.,1964 26. ~Ql/P~l =[3Qlo/[3Alo = kJQl/(k + k,[AI) where [ la denotes the photostationary triplet-state concentration approached to within 1% after illumination for a period of 5/k~. Thus the original equation (5) becomes kT = k 4-k&4[Ql/(k4 4-k3[AI) which reduces to kT k + k4[Qlexp(dE/RT)/[A1 when k 4 k,[A]; whilst for the systemdescribed [Q]/[A] = 17/k4 (mole/mole) and the calculated values for the transfer constants given in the Table should be multiplied by a factor of 2 which no longer appears in equation (8).(Received February loth 1964.) Transfer of Three Carboxylato-groups from Cobalt(1n) to Chromium(I1) By P. B. WOOD and W.C. E. HIGGINSON* THEreduction of cis-diacetatotetra-amminecobalt-(111) and oxalatotetra-amminecobalt(n1) by Cr2+ is accompanied by the transfer of two carboxylato- groups since these appear as ligands in the substitu- tion-inert chromium(rr1) pr0duct.l We have recently investigated the rapid reactions between Cr2+ and (i) the sexidentate complex ethylenediaminetetra- acetatocobaltate(m) Co(Y)- and (ii) trioxalato- co baltate(rn) Co(C 20,) 2-. Experiments were done in an atmosphere of nitrogen by adding a solution of aquochromium(n) perchlorate to a solution con- taining a small excess of the appropriate complex dissolved in dilute perchloric acid at ca.20”; the nature of the products was determined by ion- exchange chromatography and from their visible spectra. For both cobalt(rr1) complexes the nature of the chromium(1n) product depended upon the hydrogen-ion concentration of the reaction mixture. At hydrogen-ion concentrations below 0.01~for Co(Y)- and below 0.02~for CO(C,O~)~~- at least 90 % of the chromium(n1) product is attached to three carboxylato-groups;with the latter oxidant the pro- duct appears to be Cr(H,0)3(C20P)02CC02- which contains one bidentate and one unidentate oxalato- group. At hydrogen-ion concentrations above 0.13~ for Co(Y)- and above 0.2~ for CO(C,O,),~- 90% or more of the chromium(rr1) product contains two * Chemistry Department The University Manchester 13.l Fraser J. Amer. Chem. SOC.,1963 85 1747. * Kopple and Miller Proc. Chem. Soc. 1962 306. carboxylato-groups as ligands and this product is Cr(H20),(C204)+ for the reaction involving C0(C2O,),3-. The chromium(m) products appear to be mixtures of the forms with two and with three carboxylato-groups for reactions conducted at hydrogen-ion concentrations between these limits. This behaviour is presumably linked with protona- tion of the complexes a phenomenon which has previously been suggested2 to account for the acid catalysis observed in the reduction of certain di- car box yla t ot et r a-ammineco bal t (m) complexes by Cr2+. If the transfer of all three carboxylato-groups observed in the less acid solutions occurs simul- taneously as part of the oxidation-reduction process then the transition complex is triply bridged.A model of such a transition complex shows that Cr2+ can only form three bonds with the oxidant if the “alco- holic” as distinct from the “ketonic” oxygen atoms of the carboxylato-groups of the oxidant are in- volved. That is all three bridges must be of type (X) rather than (Y). (Received February 14th 1963.) 110 PROCEEDINGS Oxidation of Saturated Alcohols by Manganese Dioxide By I. T. HARRISON* ACTIVATEDmanganese dioxide at about 20” is regarded as a reagent specific with few exceptions,l for the oxidation of allylic or benzylic primary and secondary alcohols to the corresponding unsaturated aldehydes and ketones although saturated secondary alcohols would also be expected to react.We find that given sufficient reagent and purified solvents both primary and secondary saturated alcohols are in fact oxidised in high yield. Thus 5a-androstan- 17p-01 (100 mg. 0.36 mole) stirred in hexane or acetonitrile (20 ml.) with active manganese dioxide3 (2 8.) for 20 hr. gave pure 5a-androstan-17-one in 99 %yield. The rate of the reaction is dependent upon the solvent used. Thus in dimethylformamide 4 days were required for complete oxidation while in dimethyl sulphoxide oxidation was still incomplete after 7 days. The failure of other workers to observe this oxidation can be attributed to use of smaller proportions of manganese dioxide to use of solvents which normally contain saturated alcohoIs as im- purities e.g.chloroform and acetone or to the presence of the more reactive allylic alcohol which consumes most of the reagent. By using the same ratio of compound to man- ganese dioxide (mmole/g.) 4-methylcyclohexanol gave after 3 days in acetonitrile 4-methylcyclo- hexanone (71 %yield). A 707; yield of n-butyr- aldehyde could be obtained by filtration of a benzene solution of n-butanol through a column of man-ganese dioxide. Stirring the reactants together gave *Svntex S.A.. Mexico. D.F. n-butyraldehyde initially but this was rapidly oxidised further until after 24 hr. only traces re- mained. From 3p-hydroxy-5 a-androstan-17-one (I) or its 3 a-epimer there was obtained after oxidation in acetonitrile for 20 hr.an almost quantitative yield of 5 a-androstane-3,17-dione.Similarly the primary alcohol (11; R =CH,.OH) gave the aldehyde (11; R =CHO) in 76% yield after 6 hr. The hindered hydroxyls of androst-5-ene-3L?.17B.- ,’ I’ 19-trio1 3,17-diacetate and 25D-spirost-5-ene-3P,ll/’?-. diol3-acetate were unaffected by manganese dioxide. Of particular interest is the oxidation of d5-3/’?-ols which has already been shown to yield 4,6-dien-3- ones (Amax. 284 mp) when the reaction is carried out in hot benzene s~lution.~ The reaction takes a different course in dimethylformamide or pyridine at 20” leading to d4-3-ones (Amax. 241 mp) but at a very low rate.Cholesterol for example could not be oxidised at a useful rate. Oxidation of androst-5-ene- 3p,17p-diol for 3 days in dimethylformamide re- sulted in specific oxidation of the 17-alcohol group; 3p-hydroxyandrost-5-en-17-0ne was isolated in 667& yield. (Received,February 1Oth 1964.) Eians Quait. Rev.,1959 13 61. Harfenist Bavley and Lazier J. Org. Chem. 1954 19 1608. Supplied by Beacon Inc. or prepared according to the procedure of Attenburrow Cameron Chapman Evans Hems Jansen and Walker J. 1952 1094. *Sondheimer Amendolla and Rosenkranz J. Amer. Chem. SOC.,1953 75 5932. Square-planar Cobalt Complexes in Singlet and Triplet Spin States By E. BILLIG,H. B. GRAY,S. I. SHUPACK, J. H. WATERS,and R. WILLIAMS* WE recently reported the preparation and charac- terisation of Co(TDT),,t the only square-planar complex reported to date which has a spin-triplet ground state.l The absence of axial perturbations on the energy levels of Co(TDT) is indicated by the constancy of its electronic spectrum under widely varying solution conditions.Magnetic moments of [AsMePh,][Co(TDT),] are 3.15 B.M. (solid) 3.29 B.M. (cyclohexanone solution) 3-39 B.M.(pyridine) 3.40 B.M. (DMF) and 3-39 B.M. (dimethyl sul- phoxide; DMSO). The Co(MNT),- complex prepared2 by oxidation of Co(MNT)?- is electronically similar to Co(TDT),- and might be expected to exhibit similar magnetic properties. However solid [NBun4]-[Co(MNT),] is diamagnetic. Its solutions in cyclo- hexanone are diamagnetic and exhibit a spectral band at 790 mp.In pure DMSO the band shifts to *Department of Chemistry Columbia University New York 27 New York USA. t Abbreviations used :TDT =4-MeC6H,(.S-),-1 ,2; MNT =cis-SC(CN)=C(CN).S-. Gray and Billig J. Amer. Chem. SOC.,1963 85 2019. Davison Edelstein Holm. and Maki Inorg. Chem.,1963,2,1227. APRIL1964 715 mp and the complex has a magnetic moment of 2-81 B.M. Presumably the small perturbation on the energy levels by DMSO is sufficient to change the ground state to a spin-triplet. Intermediate moments are observed in mixtures of cyclohexanone and DMSO indicating that both the singlet and triplet states are present and the material can be recovered unchanged. In pyridine Co(MNT) is green (band at 685 mp) and diamagnetic.The complete electronic spectrum in pyridine is considerably different from that in cyclohexanone and DMSO. Thus it is likely that the 685 mp band is not related to the 790 and 715 mp bands in the brownish-black C,H,,O and DMSO solutions. Apparently the axial perturbation is strong enough to raise the energy of the molecular orbital derived from d,~ sufficiently for spin pairing to occur. A diamagnetic complex "Bun4]-111 [Co(MNT),(py)] was isolated. Also the diamagnetic green [NPr",],[Co(MNT),] complex was prepared. The electronic spectrum of Co(MNT),% is very similar to that of Co(MNT) in pyridine. Thus in the complex CO(MNT)~- we have observed for the first time a change from low-spin to high-spin and back to low-spin on varying degrees of solvent perturbation.It is improbable that the diamag-netism of Co(MNT),-in cyclohexanone is due to strong exchange interaction between associated anions since the presumably isostructural com-plexes Fe(MNT),- and Ni(MNT) exhibit magnetic moments in cyclohexanone expected for S = 3/2 and S = 1/2 respectively. For [AsMePh,]-[Fe(MNT),] peff = 3-73 B.M.; for [NBun,]-[Ni(MNT),] peff = 1.76 B.M. (Received January 3rd 1964.) Thioderivatives of /%Diketones By S.H. H. CHASTON and S.E. LIVINGSTONE* WE have prepared the thio-derivatives RC(SH):CHCO.R (R = Me R' = Me Ph OEt; and R = Ph; R' = Ph OEt) of diketones in order to study their metal complexes. The base-catalysed action of hydrogen sulphide on p-diketones in a polar solvent to yield monothiodi- ketones has been briefly described;l the reaction requires about 7 hours.Using Reyes and Silverstein's modification2 of Mitra's method3 we have prepared 4-mercapto- pent-3-en-2-one as a golden-yellow oil nlDg 1.556. However this method does not give the required product from benzoylacetone or dibenzoylmethane ; they were however prepared by dissolving the di- ketone in alcohol saturated with hydrogen sulphide at -10" and passing dry hydrogen chloride into the solution for 5 min. Dibenzoylmethane gave red crystals of 3-mercapto-l,3-diphenylprop-2-en-l-one (75 %) m.p. 78" and benzoylacetone orange crystals of 3-mercapto-1-phenylbut-2-en-1 -one (70 %) m.~.~ 28 O. Mass spectrographic investigation of the latter showed that the sulphur is attached to the same carbon atom as the methyl group i.e.it is The infrared spectra of these five thio-derivatives show no SH band at ca. 2570 cm.-l; this indicates strong chelation as in acetyla~etone.~ All the com- pounds display three characteristic strong absorp- tion bands ;1640-1 587 (C 20stretch) 1565-1 530 (C -C stretch) and 1240-1190 cm.-l (C -S stretch). Alcoholic solutions of 3-mercapto-l,3-diphenyl-prop-2-en- 1 -one and 3-mercapto- 1-phenylbut-2-en-1-one slowly deposit pale yellow isomers of higher m.p. ; the infrared spectra of these isomers are similar to but not identical with the spectra of the analogues from which they are derived. Whereas p-diketones react with nickel salts only in alkali to yield insoluble pale-green dihydrates that are octahedral and paramagnetic the deeper coloured isomers of the thio-derivatives react with nickel acetate solution to give brown crystalline anhydrous complexes that are diamagnetic and presumably square-planar and are readily soluble in organic sol- vents.However the pale isomers yield the identical nickel complexes only in presence of alkali. MeC(SH) :CH-CO.Ph. This quicker method can All compounds reported gave satisfactory ana- also be used to prepare ethyl thioacetoacetate; ethyl lytical data. thiobenzoylacetate,2 and 4-mercaptopent-3-en-2-one. (Received February 17th 1964.) * School of Chemistry University of New South Wales Kensington N.S.W. Australia. Mayer Hiller Nitzschke and Jentzsch Angew.Chem. Internat. Edit. 1963 2 370. Reyes and Silverstein J. Amer. Chem. SOC.,1958 80 6367 6373. Mitra J. Ind. Chem. SOC.,1933 10 71. Livingstone and Shannon unpublished work. Rasmussen Tunnicliff and Brattain J. Amer. Chem. SOC.,1949,71,1068; Mecke and Funck 2.Elektrochem. 1956, 60,1124; Cotton in "Modern Coordination Chemistry" (Lewis and Wilkins eds.) Interscience New York 1960 p. 37s. PROCEEDINGS Spectroscopic Studies of Reactions of the OH Radical By G. E.ADAMS and J. W. BOAG* BY using the optical absorption spectrum of the hydrated electron1v2 rate constants for many radiation-induced electron reactions have been determined. Since no convenient absorption spec-trum for the OH radical in solution has yet been found similar studies have not been possible for reactions of this species.From a recent study of the effect of carbonate ion on the absorption spectra found in both oxygenated and de-aerated aqueous solutions3 it now appears that the enhancement of the hydrated electron spectrum in de-aerated carbonate solutions1 was due to a contribution from the carbonate radical-ion. By the technique of pulse radiolysisl we have found that this absorption spectrum has a peak at 6000 A not suppressed by oxygen. Under the exist- ing conditions it disappears by a second-order reaction lasting tens of microseconds. When other OH scavengers are added to an oxygenated solution the initial intensity of the carbonate radical-ion peak is reduced or eliminated often with the appearance of other transient spectra.These spectra associated with reactions of the OH radical have been observed for several ions including nitrite thiosulphate thio- cyanate bromide iodide et~.~ For the reactions kl OH. + COZ-C03.-+ OH-(1) k2 OH + solute -products (2) it can be shown that Do/D = 1 3-(k2/kl)([solutel/[C0,2-1) (A) where Do and D are the absorption intensities at 60oO A for the carbonate radical-ion in the absence and presence respectively of a given concentra- tion of OH scavenger. The figure shows experimental data. The slopes of the plots give the following values of k,/kl :bromide 1.6; ethanol 3.6; glycerol 5.3; sulphite ion 15; thiocyanate ion 16; bisulphite ion 26; nitrite ion 32. Additional confirmation that the radical OH is involved in these reactions is provided by the fact that for the ionic solutes k increases with the standard potentials* for the general reaction Mn-+ OH +M(n-1)-+ OH-(3) The relative values thus obtained should be independent of dose rate of dose distribution in the cell and of extinction coefficient of the radicals in- volved.By a suitable choice of absorbing species from among the many transients already observed similar competition studies are being carried out at acid pH. The absolute rate constant for a given species can be determined from a study of the rate of build-up of the corresponding transient spectrum at a low value of dose per pulse using the higher sensitivity of the photomultiplier technique.Glycerol CP 10 20 30 40 C Concn. mM Data plotted in accordance with equation A. All spectra were taken 5 psec. after a single 2-psec. pulse of 2 MeV electrons. Mean dose to the solution 30 krads. [Na2C03]0.04~. Solutions saturated with oxygen. We have also observed other transient spectra in irradiated oxygenated wate13v5s6 which involve both the hydroxyl radical and the hydrated electron. In particular a strong peak at 4300 A is present in solutions containing >10-%-potassium hydr~xide.~~~ This is attributed to the 03-radical ion formed by reaction of O2 with OH or its ion 0-,since it is eliminated by OH scavengers. (Received February 24th 1964.) * Research Unit in Radiobiology British Empire Cancer Campaign for Research Mount Vernon Hospital North- wood Middlesex.Boag and Hart Nature 1963 197 45; Hart and Boag J. Amer. Chem. Soc. 1962,84,4090. Keene Nature 1963 197 47. Boag and Adams XVIII Ann. Symp. Cellular Radiation Biol. Houston March 1964 in press; Adams and hag to be published. Parsons,“Handbook of Electrochemical Constants,” Butterworths Scientific Publications London 1959. Baxendale Fielden Capellos Francis Davies Ebert Gilbert Keene Land Swallow and Nosworthy Nature, 1964,201,468. Czapski and Dorfman J. Phys. Chem. in press. APRIL1964 113 The Catalytic Dehydration of Aromatic Carbinols by Acids By A. GANDINI and P. H. PLESCH* THE dehydration of aromatic carbinols to olefins by acids although well known does not appear to have been studied under rigorously defined conditions.We have investigated the interaction of perchloric acid (104-10-3~) in methylene dichloride with 1,1,2,2-tetraphenylethanol (A) 1,1,2-triphenyl-ethanol (B) 1,l -diphenylethanol and l-phenyl-ethanol (all 10-3-10-2~) through the U.V. and visible spectra of the systems with a Unicani SP 700 instru-ment. All mixtures were prepared from carefully dried reagents under high vacuum in all-glass apparatus without taps or joints. The spectra of the mixtures could be recorded within about 30 sec. of mixing the carbinol with the acid solution. With all the carbinols it was found that by the time the first spectrum was recorded the carbinol had disap- peared completely and an equivalent quantity of the olefin had been formed.The solutions remained colourless during this time. The fact that even with a molar ratio of carbinol to acid of about ten or more the dehydration goes to completion almost instantaneously shows this to be a truly catalytic reaction the driving force for which is not provided by the hydration of the acid. The subsequent protonation of the olefins to carbonium ions-shown by the characteristic spectra -is a relatively slow reaction the rate and kinetics of which depend on the nature of the olefin the rela- tive concentrations of olefin and acid and through the original ratio of carbinol to acid concentrations on the extent of hydration of the perchloric acid. Addition (under open conditions) of concentrated sulphuric acid to 10-5-10-4~-sol~tions of 1,1,24rL phenylethanol in glacial acetic acid to give solutions 1-10~ with respect to sulphuric acid also resulted in instantaneous and complete dehydration followed by a slow protonation of the olefin.Other authors' have based mechanistic arguments on the assumption that the carbonium ions detected spectroscopically were formed directly by inter-action of carbinol and acid. Our demonstration that this does not occur readily under the usual condi- tions shows the basis of their arguments to be fallacious. The slowness of the dehydration of (A) and (B) by perchloric acid in acetic acid solution in an open system2 may be due to the different medium or more probably the presence of water. (Received February 14th 1964.) * Department of Chemistry The University Keele Staffordshire.Inter af.,Grace and Symons J. 1959 958; Jordan and Treloar J. 1961 729. Diss. Ah. 1958 18 389 and La Vonne Ph.D. Thesis University of St. Louis 1957. The Reactions of Cobalt(rI1) with Chloride By T. J. CONOCCHIOLI* and N. SUTIN* G. H. NANCOLLAS,~ THE instability of free cobaltic ions in solution precludes precise equilibrium measurements of its complexing with anions. The problem appears to be somewhat more tractable by kinetic measurements and a study has been made of the reactions of cobalt(Ir1) with chloride ion by a flow technique.l On mixing solutions of cobaltic perchlorate with hydro- chloric acid each adjusted to the same acidity and ionic strength with perchloric acid and sodium per- chlorate two distinct changes in optical density are observed in the wavelength range 280-330 mp.An initial increase in absorbance which is associated with the formation of a cobalt(mI)-chloride com- plex is followed by a slow decrease arising from the reduction of cobalt(rI1) by chloride. Provided that the oxidation-reduction reaction is sufficiently slow that the chloride is present in excess and that only the monocomplex is formed the half-time for the formation of CoC12+ is given by 0*693/t1/,= ki(CI-) + k-1 where the rate constants are defined by the equation kl co3++ ci-+ coci2+. k-1 At an ionic strength of 3-0h.1,this equation was followed in the concentration ranges [CO(III)]= 3-0-14 x 10-4hI [CO(II)]= 2-5-25 x 10F3~ (Cl-) = 0.01-0-10~ and (H+) = 1.0-3.0~.Values of k and k- are given in the Table; the average value of the association constant Kl = k,/k- = 25 f5 1.mole-l at 25-0". Complex formation rate constants at 25-0" (H+) (MI 1-0 1.3 2.0 3.0 k (1. mole-' sec.-l) 30 25 16 10 k- (sec.-l) 1.3 1-0 0.6 0.4 The acid dependence of the rate constants is * Chemistry Department Brookhaven National Laboratory Upton L.I.,N.Y. U.S.A. f Visting scientist from the Chemistry Department The University Glasgow W.2 Scotland. Dulz and Sutin Inorg. Chem. 1963 2 917. 114 PROCEEDINGS similar to that found in the iron(m)-chloride chloride directly from the complex. Ferric chloride system.2 However the range of acidity used in this was observed to react with thallium(m) in a similar work is too small to justify a more detailed analysis manner but at a considerably greater rate perhaps in terms of acid-dependent and acid-independent reflecting the increased lability of the ferric chloride paths.In an attempt to obtain k- directly the re- complex. It is likely that these reactions proceed via action of CoC12+ with thallium(m) was studied. It intermediates in which the cobalt (or iron) is bonded was found however that in addition to reaction to the thallium via a chloride bridge. with free chloride ions the thallium(m) abstracted (Received January 24th 1964.) Connick and Coppel J. Amer. Chem. SOC.,1959 81 6389. Delayed Fluorescence in Pulse Radiolysis of Anthracene Solutions in Benzene By JUDITH M.NOSWORTHY and J. P. KEENE* DELAYED fluorescence in solutions of anthracene directly excited by light can originate in the inter- action of two triplet-state mo1ecules.l Using apparatus described elsewhere,2 we have observed such fluorescence from solutions of anthracene in benzene excited by 4-Mev electrons and have fol- lowed its time variation. With a 2 psec. electron pulse of about 7000 rads and no additional light we found long-lived light emission from a de-aerated O.O35~-solution of anthracene in benzene. The -1.0 1. maximum emission occurred at about 4300 A a which is the wavelength appropriate to normal or 00 delayed fluorescence. 0. 0. A high pressure xenon lamp was used to measure the absorption spectra of transient species present at 0 ‘rr 0 a various times after the pulse.In agreement with -g -2.0 -a a McCollum and Wilson? we found a significant yield 0 O0 a of triplet anthracene. If4 the molar extinction co- L a efficient E at 4300 8,were 7 x 104 the 100ev yield a 0 0 0 0 00 of triplet anthracene would be G -0.7.This is a rough estimate because there may be a large error in N -OO 0 0 0 E which has not been determined under our condi- 0 tions. The highest concentration of triplet anthracene -3-0-0 0 0 observed after the pulse in 0.001M-solution was only about 10% lower than in O-O35~-solution indicating 0 an efficient mechanism of energy transfer from 0 benzene to anthracene. The intensity of light emis- sion was small compared with the amount of light e0 passed through the sample from the xenon lamp so 20 40 60 ;he rate of decrease of absorption after an electron Time after pulse (microsec;) pulse could be measured with little interference.The observed intensity of light emission I at Hot Of 2 log D (Solid Circles) and log I (open of anthracene in benzene 4300 A was approximately proportional to the circles) for O*O35~-solutions square of the optical density D at 3700 A or at 4300 &following a singlepulse of 4 Mev electrons. 4300 8 (see Figure). This is in conformity with the units Of I are arbitrary. mechanism of delayed fluorescence. The logarithmic (Received March 3rd 1964.) * (J.M.N.) Physics Department Guy’s Hospital Medical School London S.E.1; (J.P.K.) Paterson Laboratories Christie Hospital and Holt Radium Institute Manchester 20.Parker and Hatchard Proc. Chem. SOC.,1962,147; Proc. Roy. Soc. 1962 A 269 574. Keene J Sci. Inst. in press. 3 McCollum and Wilson United States ASD Technical Report 1961 61-170. Porter and Windsor Proc. Roy. Soc. 1958 A 245 238. Berlman Grismore and Oltman Trans. Faraday SOC.,1963 59 2010; Jackson Livingston and Pugh ibid., 1960 56 1635. APRIL1964 115 Linear Free-energy Relations for the Rates of Ionisation of 4-Substituted Diphenylmethyl Chlorides By J. R. Fox and G. KOHNSTAM* THE effect of 4-substituents (X) on the rates of ionisation of three 4’-substituted diphenylmethyl chlorides [#-Me0 (I) 4‘-H (lI) 4’-NO2 (111)] has been obtained in aqueous acetone under constant experimental conditions.Electron-donation towards the reaction centre unambiguously accelerates these reactions and the systems are structurally favour- able to conjugative electron-release by X in the transi- tion state. Relative rates (k,/k,) follow the pattern expected from the polar properties of X and the increase of kx/kHin the order I < I1 < I11 is consistent with the behaviour predicted from the polar properties of the 4‘-substituents. demanding reactions’ can be expressed in the more general form log (kx/k~) = oaxpa fUbpb (2)t where the substituent constants oaxand Ubx reflect the magnitudes of the electron-release resulting from the permanent polarisation and polarisability of X respectively and always have the same value for a given X.The corresponding reaction parameters pa and pb are independent of the 4-substituent X but they depend on the nature of the parent compound and will therefore have different values in series I 11 and 111. A 4-nitro-group is at best only very slightly Relative rates [log (kx/kH)] for the ionisation of 4-substituted diphenylmethyl chlorides in 85% (vlv) aqueous acetone at 0” (k at zero ionic strength when necessary from rates at other temperatures via the energy entropy and heat capacity of activation; all errors are standard errors.) 4-substituent (X) 4‘-Me0 (I) 4’-H (11) 4‘-NO2 (III) NO2 -2.024 f0.002 -3.195 f0.032 -3.932 f0.028 c1 -0.366 f0.003 -0.511 f0.002 -0.403 f0.020 F 0.113 f0.005 0.293 & 0.002 0-555 f0.016 Ph 0.484 f0.012 0.911 f0.005 1-298 f0.014 But 0.671 f0-011 1.126 f0.005 1.380 f0.014 Me 0.865 f0.014 1-466f0.005 1-862f0.014 An* 1.012 f0.012 1.921 f0.005 2.730 f0.033 PhO 1.401 f0.038 2.837 f0.005 3.669 f0.032 Me0 2-403 f0.042 4.589 -l0.005 5.724 f0.032 * An = 4-MeOC,H4.Various sets of substituent constants (uX) have been suggested1 for use with the Hammett relation log (kX/kH) = (11 If any single set of values of OX is applicable to the present reactions the ratio R = log (k,/k,)/log (kNoJkH) should have the same value for compounds I 11 and 111. Our results however yield RI> RII > RIII,except for X = t-Butyl. Since R is negative these observations probably arise from the use of polarisable substituents conjugated to an electron- demanding reaction centre (cf.ref. 2). Extensions of eqn. (1) which attempt to allow for the operation of polarisability effects in electron- polarisable with respect to an electron-demanding reaction centre (cf. ref. 5); i.e. UbNoe N 0. Eqn. (2) then yields R = log (kx/kH)/log (k,od/kH) = ~aX/~aNo* -k (ObX/oaNo2)(pb/prt) and hence The ratio P should therefore be independent of the nature of X,$ but this requirement is not met by our results; P varies from 0-266 f0.024 for X = C1 to 0.928 f0.128 for X = MeO. The present work was carried out on three similar * Science Laboratories South Road Durham. Some restrictions have previously-been placed on the parameters in eqn. (2); e.g. pb = p&3 or 0 = of -u.~ $ This test is only applicable to polarisable substituents.When 05 = 0 RII-RI = RIrr -RI = 0. Wells Chem. Rev. 1963,63 171; Brown and Stock “Advances in Physical Organic Chemistry,” Vol. 1 Academic Press London 1963 p. 35; and references there cited. Lewis and Taft J. Amer. Chem. Soc. 1959 81 5343. Knowles Norman and Radda J. 1960,4885. Tsuno and Yukawa Bull. Chem. SOC.Japan 1959,32,971. Bekkum Verkade and Wepster Rec. Trav. chim.,1959,78,815; Brown and Okamoto J. Amer. Chem. SOC.,1958, 80 4979. systems. It therefore seems likely that the existing linear free-energy relations or even those involving four disposable parameters will not be successful in the accurate prediction of rates when polarisable substituents are conjugated to an electron-demanding PROCEEDINGS reaction centre.Eqn. (2) probably fails because it does not allow for the possibility that a given electron-demand may invoke maximum electron release from some substituents but not from others. (Received February 21st 1964.) Chromium(r1) Reductions of Rhodium(rr1) and Iridium(m) Complexes By G. T. TAKAKI and R. T. M. FRASER* WE report results of electron-transfer experiments involving metals which are substitution-inert in both their oxidised and reduced states. We have studied the reaction between [(NH3),MXI2+ and chromium- (II) ions where M is rhodium(rI1) or iridium(II1) and X is chloride bromide iodide or acetate. The products of the reduction of the rhodium complexes are ammonium ion rhodium metal and an aquochromium(n1) complex containing the ligand X.Precipitation of rhodium occurs fairly rapidly when an excess of chromium(I1) is used but com- mences only many hours after the primary electron transfer has taken place if the rhodium(n1) complex The rates of reaction were followed spectrophoto- metrically and at least a twenty-fold excess of chromium(I1) was added to make the rate of inter- mediate formation of pseudo-first order R = k [(NH3),M1IIX2+] where kl = k[Crn]. Some of the binuclear intermediates formed in the reductions are sufficiently stable for consecutive kinetics to be observed. The table lists ratios of k,/k, where k2 is the constant for the rate of Cr(m) appearance together with the values of k and k and for those reactions where consecutive behaviour could not be detected because of the small value of k2/kl the overall second-order rate constant kbi.Summary of rate constants at 25"c ([MI111 = 1.0 x 10-3~,[CrII] = 2.0 x 10-2~,p = 1.0) Complex k2lkI kl k hi (sec.-l) (1.mole-l set.-') (].mole-l sec.-l) (NH3)5RhC12+ 0.6 1.8 x 0.89 (NH3),RhBr2+ --1-3 x (NH3)5Rh12+ (0.075 -7.0 x 10-3 (NH3),RhOAc2+ (0.1 -2.8 x 10-3 (NH&IrCl2f (NH,),IrBr2+ 0.2 1.1 2-6 x 3.2 x (NH3)&I2+ 0.5 2.4 x is present in excess. The pH of the solutions remains constant until this metal precipitation starts indicat- ing that the rhodium(I1) species still contains five ammonia groups per rhodium (NH3),RhIIIX + CrII --f (NH3),RhIIIXCr1I (NH3)5RhIIIXCrII (NH3)5Rh11XCrIII} k1 3 (NH,),RhIIXCrII-(NH,)5RhII + XCrIII.k The nature of the rhodium(I1) ion has not been characterised beyond this-it may be a pentammine- aquo-complex or a dimer [(NH3),Rhu]t+. The co-ordinated ammonia is not liberated during the formation of chromium(II1) in the iridium reactions there is no metal precipitation and the ligand X is not transferred to the chromium during electron transfer. This parallels the behaviour in the reduction of IrCl,% by Cr2+ where the reaction pro- ceeds through a bridged activated complex but where the chlorine bridge is retained by the iridium and not transferred to the chr0miurn.l 10-3 0.13 10-4 1-6 x 10-4 1.2 x Although a bridged activated complex is involved in both series the rates decrease in the order chloro > bromo > iodo in contrast to those observed in the ieduction of pentammine-cobalt(1Ir) or -chromium(m) complexes.2 This arises from the fact that CoIII and CrIII are class (a) acceptor^,^ with decreasing affinity for the ligands in the order F $ C1 > Br > I whereas RhIII and IrIII are class (b) acceptors with opposite affinities I > Br > C1 8 F.The differences in substitution-inertness lead to trans- fer of the bridging group from rhodium to chromium but not from iridium to chromium. The reduction through acetate is an interesting case since ion- exchange experiments at 25 O show that at least 80 % of the acetate remains attached to the rhodium after reduction (NH3),RhI1IOAc + CrII-+(NH,),Rh*IOAc + CrIII presumably because of the increased affinity of rhodium for the oxygen of the carboxyl group.(Received January 21st 1964.) * Department of Chemistry The University of Kansas Lawrence Kansas U.S.A. Taube and Myers J. Amer. Chem. SOC.,1954 76 2103. Taube Cunud.J. Chem. 1959,37 129. Arhland Chatt and Davies Quart. Rev. 1958 12,265. APRIL1964 117 Chemiluminescence from the Reaction of Chlorine with Aqueous Hydrogen Peroxide By R. J. BROWNE and E. A. OGRYZLO* IN 1960 Seligerl reported that the reaction between hydrogen peroxide and sodium hypochlorite (in acidic solution) or chlorine (in basic solution) gives rise to a red chemiluminescence. He recorded one emission band at 6348 A but made no attempt to identify the source of the emission.More recently Khan and Kasha2 reported a second band at 7032 8 for this reaction. In view of the 1567 cm.-l spacing between the bands they tentatively assigned the bands as solvent shifted (0,O) and (0,l) bands of the lC,++-+ 3Cg-system in oxygen. Arnold Witzke and Ogryzlo3 showed that this assignment could not be correct since the same two bands are observed in the products of electrically discharged pure gaseous oxygen. We have recorded the emission spectrum from this reaction with a cooled RCA-7 102 photomultiplier and an f 4.6 Hilger-Watts spectrometer. Chlorine was bubbled into an alkaline solution of 30 % hydro-gen peroxide in water. The spectrum of the emission (which comes from the bubbles) is shown in Fig.1. The spectral sensitivity of the photomultiplier is indicated with the dotted line. The overall reaction can be written C1 + H02-+ OH-2C1-+ H,O + 0,.(1) All the bands observed can be assigned to known transitions of O,(lC,+) and O,(ld ,). Since the photo- multiplier sensitivity beyond 12,000 8 is about 5 x lo4 of the maximum value the emission at 12,700 A (peak 8) is probably the most intense detected. This is undoubtedly the (0,O)transition in the O,pd +-+ 3Cff-)system. Peak (7) at 10,700 A is then the (1,O) transition in the same system indicating the presence of vibrationally excited O,(ld ,). In view of the known efficiency of water in deactivating vibrationally excited oxygen the large (l,O) intensity is sur-prising.Peak (2) is due to a weakly bound complex of two 02(ldg) molec~les.~ Peak (3) arises from the same complex when one of the oxygen molecules ends up in the first excited vibrational level. Band (1) at 5800 8 confirms the presence of vibrationally excited 02(Qlg) since it arises from a complex be-tween O,(ld JU=, and O,(ld B)v-l. Peak (4) at 7619 A and peak (6) at 8645 A are the (0,O) and (0,l) transi- tions in the O,(lC,+ ++ 3Cg-) system. Since water rapidly deactivates 02(1Cg+),5 these peaks are most intense when the reaction mixture is cooled to reduce the vapour pressure of water. Peak (5) at 7700 A which we assign as the (1,l) transition in the same system provides further evidence for vibrational excitation in oxygen.06 065 0.7 08 09 1.0 1.2 1.4 Wavelength (p) FIG. 1. Emission spectrum from the reaction of chlorine and hydrogen peroxide obtained with a 500 p slit width. The broken line gives the relative spectral sensitivity of the photomultiplier. The amplification for curve (A) = lo00 times the amplification for curve (B). The production of oxygen in excited “singlet” states can probably be traced to the spin conserva- tion requirement in reaction 1 (or one of its more elementary steps). Since molecular oxygen seems essential for bioluminescent processes and peroxide intermediates appear to be formed such processes may in some ways resemble the present reaction. (Received February 7th 1964.) * Department of Chemistry University of British Columbia Vancouver 8 Canada.* Seliger Analyt. Biochem. 1960 1 60. Khan and Kasha J. Chem. Phys. 1963,39,2105. Arnold Witzke and Ogryzlo J. Chem. Phys. in press. Knotzel and Knotzel Ann. Physik 1948 2 393. Bader and Ogryzlo Discuss. Paraday SOC.,1964 April. White “Light and Life,” The Johns Hopkins Press Baltimore 1961 p. 183. PROCEEDINGS -~ ~~ ~ Absolute Configuration of Some Carbohydrate Benzylidene Derivatives By N. BAGGETT M. H. RANDALL,and J. M. WEBBER* K. W. BUCK,A. B. FOSTER THE acid-catalysed reaction of benzaldehyde with polyhydric alcohols to give 2-phenyl-l,3-dioxan and 2-phenyl-l,3-dioxolan derivatives affords diastereo- isomers only in the latter case;l several pairs of diastereoisomers have been reported.24 The abso- lute configuration hitherto unknown can be assigned to these compounds on the basis of n.m.r.spectroscopy a Varian A60 instrument being used on ca. 10% solutions inp-dioxan; chemical shifts are recorded on the 8 scale. The chemical shifts for the benzyl protons in 2-phenyl-l,3-dioxans with equatorial substituents variously in the 4- 5- 43- and 4,6-positions were in the range 4-98-5-14 and for several compounds containing 2-phenyl-l,3-dioxan trans-fused to a tetrahydropyran ring (4,6-0-benzylidenehexo-pyranosides) in the range 5.1 6-5-1 8; 1,3:2,4-di-O-benzylidene-erythritol which has two 2-phenyl-1,3-dioxan units mutually trans-fused had 8 5.25. The benzyl proton signals for 2-phenyl-l,3-dioxolans variously substituted at position 4 with Me CH2-OH CH,-OAc [CH2],.CH,.OH and 'Pr appeared at lower field (5-33-5.54).2-Phenyl-l,3-dioxolan had a single signal at 5-34 characteristic of a benzyl proton with cis-hydrogen atoms at positions 4 and 5. Each of the 4-substituted derivatives had signals in the ranges 5-33-5-38 and 5.48-5-54 [withd6 (arithmetical difference) 0.124-14 p.p.m.1 assigned respectively to the isomers with the benzyl proton trans and cis to the substituent at position 4 (cf. the results and arguments of Abraham and Holkefl and of Perlin6). 3-0-Methyl-~-glucitoI affords two 2,4:5,6-di-0-benzylidene derivatives A (m.p. 143-144" [aID + 26.5" in CHCl, 8 5.55 5.23) and B (m.p. 112-1 16" [aID+ 25' in CHCl, 8 942,523). By analogy with the benzyl proton signals in the model compounds 1,3,5,6 -tetra -0-acetyl -2,4 -0-benzylidene -D -glucitol (5.28) and 1,3,5-tri-O-acety1-2,4-O-benzyl-idenexylitol (5~27)~ the signal at 5.23 in compounds A and B may be assigned to the 4,6-O-benzylidene group.By further analogy with the 4substituted 2-phenyl-l,3-dioxolans the signals at 5.55 and 5.42 respectively for A and B indicate the proton in the 5,6-O-benzylidene group to be cis- (I) and trans- related (11) to C-4. The isomers of 2-phenyl-1,3,5-trioxa-cis-bicyclo-[3,3,0]octane011) with endo- and exo-benzyl protons have respectively the H at position 2 cis to two alkyl groups or to two hydrogen atoms at the ring junction. The isomer mixture first prepared had signals at 5-33 and 5-64 respectively near to that (5.34) for 2-phenyl-1,3-dioxolan and at much lower field than the low-field signals for the 4-substituted 2-phenyl-l,3-dioxolans.A crystalline form of 011) (m.p. 57-58') had one benzyl proton signal at 5-64 and hence must be the 2-endo-H isomer. (I Isomer A R'= H R'L Ph) (II Isomer B R'-Ph,R#=H) Ph. ,H U I (E: Isomer C R'= H,R"=Ph) (=> OMe (n Isomer 0,R'=Ph R=H) Methyl a-D-mannopyranoside affords2 two 2,3 :4,6-di-O-benzylidene derivatives C (m.p. 180-181' [a] -1" in CHCl, 85.24 5.84) and D (m.p. 97-99' [a] -63" in CHCl, 6 5.16 5-54) to which structures (1V) and (V) can be allotted. The signals at 5-24 and 5-16 can be assigned to the 4,6-O-benzylidene group and the signals at 5-54 and 5-84 to the 2,3-O-benzylidene group with exo-and endo-benzyl protons respectively.Although the latter signals are both to lower field than the cor-responding signals in compound (III) the d8 value (0.30 p.p.m.) is of the same magnitude (0.31 p.p.m.) which suggests that in the mannoside deriva- tives there is an additional superimposed effect. This could be a function of the polysubstituted character of the tetrahydropyran ring. Crude methyl 3,4-O-benzylidene-/?-~-arabinoside~ had benzyl proton signals at 5.70 and 5.44 (d8 0.26) with strengths in the approximate ratio 1 :3 in con- trast to all the other substituted 2-phenyl-1,3-* Chemistry Department The University Edgbaston Birmingham 15. Dobinson Foster and Stacey Tetrahedron Letters 1959 No. 1 p. 1; Foster Haines Homer Lehmann and Thomas,J.1961,5005; Foster Haines and Lehmann J. 1961,5011. Robertson J. 1934 330. Oldham and Honeyman J. 1946,986. Lipkin Phillips and Hunter Tetrahedron Letters 1959 No. 21 p. 18. ti Abraham and Holker J. 1963 806. Perlin Canad. J. Chem. 1963 41 399. APRIL1964 119 dioxolan derivatives which gave signals of com-was isolated which had a single signal at 5-49 indica- parable intensity. The crude benzoylated product tive of an exo-benzyl proton in the 3,4-O-benzylidene had signals at 5.47 and 5-82 (d8 0-35) from which a group i.e. structure (VI). product (m.p. 119-120” [a] + 224” in CHCl,) (Received February 18th 1964.) Helical Polymerisation of Pseudo-isocyanine By S. F. MASON* THE salts of 1 ,l’-diethyL2,2’-cyanine (I) are mono- meric in ethanol solution but in water at concentra- tions > ~O-,M the dye forms a fluorescent polymer which from its sensitivity to quenching reagents is estimated2 to contain -lo6 monomers.It is now found that the addition of a concentrated ethanol solution of the dye (I) to an aqueous (+)-tartrate solution produces an optically-active polymer the circular dichroism of which is reported in the Figure. An enantiomeric circular dichroism curve is given by the dye polymer produced in aqueous solutions of the (-)-tartrate ion. Optical activity is induced in the absorption bands of both the monomeric and the polymeric form when the dye (I) is bound to poly- (L-glutamic acid) in the a-helix conformation but the induced activity is lost when the acid assumes the random coil form.X-Ray diffraction studies4 indicate that the polymer is thread-like with a unit cell containing eight dye molecules repeating every 35.5 8,along the fibre axis. Since the van der Waals thickness of an aromatic ring is some 3.6 A the aromatic planes of the dye monomers are orientated4 at an angle of 55-60” to the fibre axis of the polymer. Scheibe5 suggests that the polymer consists of a “coin-pile” array with the short-axis (y) and the long-axis (x) of Y xJ Y it Et each monomer inclined and normal respectively to the polymer fibre axis. Forstere indicates that the monomer long-axis (x) must be inclined to the fibre axis in the polymer since the sharp 5720 8 absorp-tion band of the polymer is known from the stream- ing linear dichroism7 to be polarised parallel to the fibre axis suggesting6 that the monomers are helically-disposed about the fibre axis.* Chemistry Department University of Exeter. Jelley Nature 1936 138 1009; 1937 139 631. Together with the results of the previous ~tudies,l-~ the present work suggests that the polymer of pseudo- isocyanine (I) is a helix with eight monomers per turn and a rise of some 4.5 8 per monomer along the helix axis. From the sign of the rotational strength of the parallel polarised 5720 A polymer band it is in- ferred that the helix produced in (+)-tartrate solu- tions is left-handed and that in (-)-tartrate solutions right-handed. The magnitude of the rotational strength of the 5720 8 circular dichroism band and the dipole strength of the 5250 8 monomer band from which the former derives in the polymer by dipole-dipole interaction give an effective helix radius (radial distance from the fibre axis to each monomer transition moment) of 4-1 A either cyclics or linearB exciton theory being used in the nearest- neighbour approximation.These estimates suggest that the 4-and 4’-CH groups of the dye monomers on opposite sides of the helix are in van der Waals contact and that the N-ethyl groups form the exterior of the helix in contact with water molecules. 5500 5000 4500 A (8.> The absorption spectrum of pseudo-isocyanine . . ...... in ethanol (monomer) and in aqueous solution (polymer) and --the circular dichroism spectrum of the polymer in aqueous di- potassium (+)-tartrate solution.(Received February 7th 1964.) Scheibe Schontag and Katheder Naturwiss. 1939 27 499. Stryer and Blout J. Amer. Chem. Soc. 1961 83 1411. Hoppe Kolloid-Z. 1944 109 21 27. Scheibe,2.Elektrochem. 1948 52 283. Forster Nuturwiss. 1946 33 166. Scheibe and Kandler Nuturwiss. 1938 26 412. Moffitt Proc. Nat. Acad. Sci. Washington 1956 42 736. Bradley Tinoco and Woody Biopolymers 1963 1 239. 120 PROCEEDINGS Triborylamines By M.F. LAPPERT and G. SRIVASTAVA* ALTHOUGHaminoboranes (i.e. derivatives of BH,-NH,) are well known,l diborylamines [i.e. derivatives of (BH,),NH] have only recently been ~btained.~~~ We now report the first triborylamine [o-C6H4O,>B],N.Derivatives of (BH2)3N are of considerable interest since by analogy with tri- silylamine (SiH,),N and its derivatives they would be expected to have a planar D3hstructure. Reaction of 2-chloro-l,3,2-benzodioxaborole O-C~H,O,B.C~,~ with hexamethyldisilazane afforded chlorotrimethylsilane and di-( 1,3,2-benzodioxaborol- 2-yl)amine which sublimes at 200"/2 mm. The latter was allowed to react with more chlorobenzodi-oxaborole in the presence of triethylamine to afford the tertiary amine and triethylammonium chloride. Tri-(l,3,2-benzodioxaborol-2-yl)amineis a crystal- line solid insoluble in common organic solvents and readily hydrolysed. It was purified by sublimation at 260"/0.1 mm. and was characterised by full ele- mental analysis and its infrared spectrum.Its mass spectrum is particularly significant for confirming its structure. The highest intensity peak is that of the parent unipositive ion at 371 mass units; the relative peak heights at mass numbers 371 372 and 373 are 100 20.2 3.3 compared with cal- culated intensities for C1,H1,B3N06 of 100 :20.26 3.15 respectively. The fragmentation pattern is readily interpreted. Also of interest are the presence of peaks at 1844 185 and 1854 and at 123 1234 and 1238 which clearly arise from doubly-charged and triply-charged molecular ions respectively. Such ions are not normally observed at this relatively high a bun dance. We interpret the stability of this tertiary amine as caused by the presence of chelated structures which not only prevent overcrowding at boron but without which we would expect 1,3-nucleophilic rearrange- ments of the type reported earlier to occur.Thus (BF,),N is unlikely to be stable (cf. ref. 4) and if transiently obtained would eliminate boron tri-fluoride. As confirmation of this view di-(1.3,2- benzodioxaborol-2-y1)amine with trichloroborane does not afford a stable diborylamine. [o-C~H~O~B],NH + BCI -2 O-C6H4O~'CI 4-[(CI,B),NH] (not isolated) -BCI + (CI-B-NH) (Received March 2nd. 1964.) * Department of Chemistry Faculty of Technology University of Manchester. Cf. Ch. 2 of "Developments in Inorganic Polymer Chemistry," ed. Lappert and Leigh Elsevier Amsterdam 1962. Lappert and Majumdar Proc. Chem.SOC.,1963 88; Adv. Chem. Ser. No. 42 (1964). Noth 2.Naturforsch. 1961 16b 618; Jenne and Niedenzu Znorg. Chem. 1964 3 68; Koster Adv. Chem. Ser. No. 42 (1.964). Buckmgham Proc. Chem. Soc. 1962 351. Gerrard Lappert and Mountfield J. 1959 1529. The Structure of Carabrone from Carpesium ubrotunoids Linn. By H. MINATO S. NOSAKA, and I. HORIBE* A NEW sesquiterpene lactone carabrone (l) C15H2003 m.p. 90-91" [a],,+ 116.9",Vmax. 1712 1758 3100 1665 and 822 cm.-l Amax. 213 mp (E 8150) was isolated from powdered fruits of Carpesium abrotanoides Linn. Hydrogenation (1 0 % palladium-charcoal in ethanol) afforded a mixture of dihydrocarabrone (11) (no absorption maximum above 200 mp Vmax. 1764 cm.-l) and the cup-un- saturated y-lactone (111) [vmax.1755 1712 1687 cm.-l; Amax. 221 mp (E 10,200)]. Moreover cara- brone afforded formaldehyde on ozonolysis so that it is an @-unsaturated y-lactone having an exocyclic methylene group. The multiplet signals centred at T 9-56 9.62 and 9.77 in the n.m.r. spectra of (I) (11) and (111) are presumably due to protons on the cyclopropane rings but the spectra of a keto-ester (IV) obtained * Shionogi and Co. Ltd. Fukushima-ku Osaka Japan. by reduction of (111) with sodium borohydride followed by hydrolysis and esterification with diazomethane shows that the skeleton of carabrone should be represented by a six- or seven-membered ring containing the cyclopropane ring isolated from the $-unsaturated y-lactone function. Carabrone has an acetyl group (iodoform by sodium hypoiodite oxidation) ; the other methyl group is on a tertiary carbon atom (a singlet at T 8-93).An oily alcohol was obtained by oxidation of (11) with trifluoroperacetic acid. Its tosylate was con- verted into tertiary amine when heated with di- methylamine and the corresponding N-oxide was degraded on heating at 100-120" and then by treatment with ozone to the aldehyde (V). From these results and study of the spectra of the inter- APRIL1964 $t+,** (11 a) 0@ H0QOzMe (=I * Taylor and Watts J. 1952 1123. mediates it is concluded that carabrone possesses a ring. CH,COCH,-CH,-grouping on a cyclopropane Dehydrogenation (palladium-charcoal) of di-hydrocarabrone 01)and reduction (Huang-Minlon) of the CI4 product gave an oil with physical and spectral properties indicative of 4- or 5-ethyl-2-pent yl t oluene .4-Eth yl-2-penty1toluene was there-fore synthesized. Friedel-Crafts reaction of p-ethyl- toluene with n-valeryl chloride should yield the 2-acyl-4-ethyltoluene (cf. ref. 1). Clemmensen reduc- tion of the product afforded 4-ethyl-2-pentyltoluene identical with that obtained from carabrone. (Received February 17th 1964.) Ionic Reactions of Perfluoroallene By R. E. BANKS,R. N. HASZELDINE, and D. R. TAYLOR* IN contrast to perfluoro-olefins which strongly resist attack by "electrophilic" reagents perfluoro- allene combines smoothly and quantitatively with hydrogen halides in the absence of light catalysts or solvents and at room temperature or below to yield 1 1 adducts CF,:C:CF t HX -+ CF,X.CH:CF (X = F C1 or Br).Thus 2H-pentafluoropropene is obtained in 99 % yield when a mixture of perfluoroallene and an excess of anhydrous hydrogen fluoride is kept in an autoclave at -72" for 12 hr. and then warmed to 20"; similar reactions involving hydrogen chloride at 20" and hydrogen bromide at -45" lead to the formation of 3-chloro-l ,1,3,3-tetrafluoropropene (99 % yield) and 3-bromo-l,1,3,3-tetrafluoropropene (89 % yield) respectively. Dihalogenotetrafluoro- propanes (CF2XCH,CF,X; X = F C1 or Br) are not formed. Like perfluoroallene allene reacts rapidly with an excess of anhydrous hydrogen fluoride at low temperatures but in this case addition of H-F to the unsaturated system takes place in the opposite direction :l -76"-0"/1 hr.CH2:C:CHZ f2HF--+CH3-CF2*CH3 (100%) Reaction of allene with hydrogen chloride at -78" in presence of bismuth trichloride gives a mixture of CH,CCl CH and CH,CC1,CH3 in which the former predominates if only one molar proportion of hydrogen chloride is used. Reaction of perfluoroallene with an excess of chlorine under ionic conditions (in the dark -72"/12 hr. then 20"/7 days) yields CF,Cl*CCl CF (99 %) whereas the same reaction in sunlight at 25" for 6 hr. gives only 5 % of this propene and the main product (92 % yield) is CF,Cl-CCI,CF,Cl. Perfluoroallene like perfluoro-olefins readily undergoes nucleophilic attack. Thus reaction of perfluoroallene with moist casium fluoride at 100" gives 2H-pentafluoropropene (100%) F-+ CF,:C:CF + CF,.E:CF,-+ H2O CF3-CH:CF2 and reaction with neutral methanol at -24" to 20" yields a 1 1 adduct CH,.OCF,CH CF,.This sug- gests that the reaction of perfluoroallene with hydrogen halides involves nucleophilic attack by halide ion rather than electrophilic attack by proton. In reactions involving ionic intermediates per- fluoroallene is thus polarised in the sense (A) illustrating the importance of back-co-ordination from the four symmetrically-placed fluorine substi- tuents (B). (A 1 (8) Similarly the U.V. absorption spectrum of per- fluoroallene shows a single maximum (Amax. -209 mp; E = 230) at longer wavelength than in allene3(Amax. = 171 mp) or its simple homologues (e.g.> EtCH :C :CH, Amax.= 170 mp). (Received February 27th 1964.) * Chemistry Department Faculty of Technology University of Manchester. Austin U.S.P.2,585,529/1952. * Jacobs and Johnson J. Arner. Chem. Soc. 1960,82 6397. Sutcliffe and Walsh J. 1952 899. Burr and Miller Chern. Rev. 1941 29 419. PROCEEDINGS NEWS AND ANNOUNCEMENTS Chemical Society Awards and Lectureships.-The Council has made the following appointments for 1964-65 Faraday Medal and Lectureship .. Pedler Lectureship Tilden Lectureship .. .. . . Centenary Lectureships .. Ethel Behrens Awards.-In Professor R. G. W. Norrish Professor W. Baker Dr. A. D. Buckingham Professor F. Sondheimer Professor F. Lynen (Munich) Professor J.C. Polanyi (Toronto) connection with the Anniversary Meetings held at Birmingham on April 7-9th 1964 the Council of the Society awarded grants from the Ethel Behrens Fund to the following Fellows :P. A. Bristow (University College London) P. J. N. Brown (University of Birmingham) P. E. Childs (St. Catherine’s College Oxford) G. P. Cotterrell (Lincoln College Oxford) D. H. Davies (University College London) R. A. Dawe (St. Catherine’s College Oxford) G. H. Dodd (Trinity College Dublin) G. Duxbury (University of Sheffield) D. W. Lappage (University of Exeter) J. Parker (Lincoln College Oxford) J. B. Reid (Christ Church Oxford) S. D. Robertson (Univer- sity of Glasgow) W. D. C. Warnock (University of Glasgow).Library.-The Library will close for the Whitsun holiday from 6 p.m. Friday May 15th until 9.30 a.m. Wednesday May 20th 1964. Election of New Fellows.-1 30 Candidates were elected to the Fellowship in March 1964. Deaths.-We regret to announce the deaths of Mr. C. H. S. Kbping (17.2.64) formerly School- master at Wednesbury High School; Lt.-Col. G. P. Pollitt (9.3.64) former Director of Imperial Chemical Industries Ltd.; Mr. G. A. Stamp (18.10.63) a Fellow for forty years; Dr. H. M. Thompson (14.2.64) Research Chemist at Tate and Lyle Laboratories; and Mr. A. W. Wesrrup (11.2.64) Lecturer at Highbury Technical College Portsmouth. Nuclear Magnetic Resonance Discussion Group.- A discussion group for chemists and those interested in the chemical applications of nuclear magnetic resonance has been formed.The first meeting will be held at the Northern Polytechnic on Friday May 22nd. Full details may be obtained from Dr. E. F. Mooney Northern Polytechnic London N.7. Royal Society.-The following were included amongst those elected to the Fellowship of the Royal Society on March 19th Professor C. H. Barnford Campbell Brown Professor of Industrial Chemistry in the University of Liverpool. Distinguished for his work on the role of free radicals in thermal and photochemical reactions and polymerisa tion processes. Dr.L. H. N. Cooper Senior Principal Scientific Officer Plymouth Laboratory of the Marine Bio- logical Association of the United Kingdom. Dis- tinguished for his studies of the chemistry and physics of sea-water of nutrient cycles in the sea and of factors influencing productivity.Professor D. D. Hey Professor of Physical Chemistry in the University of Nottingham. Dis- tinguished for his contributions to our understand- ing of heterogeneous catalysis polymerisation the kinetics of enzyme reactions and the properties of organic semi-conductors. Professor G. W.Kenner Heath Harrison Professor of Organic Chemistry in the University of Liverpool. Distinguished for his work on the organic chemistry of natural products including co-zymase and other co-enzymes polypeptides and porphyrins. Professor A. D. Walsh Baxter Professor of Chemistry at Queen’s College (Dundee) in the University of St. Andrews.Distinguished for his work on molecular spectroscopy and the structure and shape of molecules in different states of excita- tion and on the kinetics of gaseous reactions. Marchon Visiting Lectureship.-Professor R. S. Nyholm spent the fortnight of March 2nd-13th in the University of Newcastle-upon-Tyne as Marchon Visiting Lecturer. This Visiting Lectureship has been endowed by Marchon Products Ltd. of Whitehaven Cumberland to enable the University to invite dis- tinguished scientists from this country or abroad to spend some time in a Department giving lectures and having informal discussions. Professor Nyholm de- livered two general undergraduate lectures entitled “Unusual Co-ordination Numbers” and “Metal-to- Metal Bonds in Chemical Compounds,” and he also gave a research colloquium in the Department of Inorganic Chemistry on “Recent Developments in the Chemistry of Metal Carbonyls.” For his Uni- versity Public Lecture Professor Nyholm chose the broad subject “Education in Science-for Whom and for What Purpose?” This provoked lively dis-cussion both within the University and in many schools in the area Professor Nyholm spent considerable time in discussions with research students and staff in the School of Chemistry and it was particularly appropri- ate that he was able to be present as guest of honour at the Annual Dinner of the Bedson Club which is the University Chemical Society.Gordon Research Conferences.-The Gordon Research Conferences international Conferences on Developments in the most active areas of basic research will include fifty full-week sessions this APRIL1964 summer.The programme includes nine new research topics. Scheduled to open on June 15th the Conferences will continue until September 4th. The meetings each devoted exclusively to a single subject and last- ing a week will be held at five locations in New Hampshire; New London (Colby Junior College) New Hampton (New Hampton School) Meriden (Kimball Union Academy) Tilton (Tilton School) and Andover (Proctor Academy). Founded 33 years ago and originally only two in number the Conferences are designed to promote the creative interchange of ideas and communica- tions among research leaders in various scientific disciplines and in different scientific environment- academic government and industrial.The 1964 Conference subjects are Hydrocarbon Chemistry; Nuclear Chemistry; Catalysis. Polymers Textiles; Elastomers;Corrosion ;Medicinal Chem- istry; Food and Nutrition; Separation and Purifica- tion ; Cancer; Nuclear Structure Physics; Environ- mental Sciences-Microchemical Contaminants in Water; Nucleic Acids; Theoretical Chemistry; Metals and Metal Binding in Biology; Statistics in Chemistry and Chemical Engineering; Scientific In- formation Problems in Research-Critical Tables ; Radiation Chemistry; Steroids and Other Natural Products ; Inorganic Chemistry; Analytical Chem- istry; Chemistry of Heterocyclic Compounds; Adhesion; Lipid Metabolism; Solid State Studies in Ceramics; Cell Structure and Metabolism; Co-enzymes and Metabolic Pathways ; Chemistry Physiology and Structure of Bones and Teeth; Physical Metallurgy; Chemistry at Interfaces ;Toxi-cology and Safety Evaluations; Dissolution and Crystallisation of Calcium Phosphates ; Chemistry and Physics of Solids ;Infrared Spectroscopy ;Non-linear Optics ; Biochemistry and Agriculture ; Fric-tion Lubrication and Wear; Chemistry and Physics of Space Chemistry of Carbohydrates ; Chemistry and Physics of Isotopes; Organic Reactions and Processes; High-Temperature Chemistry; Biopoly- mer-Solvent Interactions and the Structure of Liquids; Organic Photochemistry ; Geochemistry-Water; chemistry and Metallurgy of Semicon-ductors; Ionic Movements and Interactions in Biological Chemical and Physical Phenomena ; Biomathematics;Biological Regulatory Mechanisms.Further information including a complete schedule of Conferences and attendance application forms may be obtained from Dr. W. George Parks Director Gordon Research Conferences University of Rhode Island Kingston Rhode Island. Symposia etc.-The Sixteenth Pittsburgh Con- ference on Analytical Chemistry and Applied Spectroscopy will be held in Pittsburgh on March 1st-Sth 1965. Further enquiries should be addressed to Dr. William A. Straub Programme Chairman c/o Applied Research Laboratory United States Steel Corporation Monroeville Pa. An International Conference on Electron Diffrac- tion and Crystal Defects organised by the Australian Academy of Science the International Union of Crystallography and the International Union of Pure and Applied Physics.will be held in Melbourne on August 16th-21st 1965. Further enquiries should be addressed to The Chairman of the Con- ference Organising Committee Dr. R. I. Garrod c/o Aeronautical Research Laboratories Box 4331 G.P.O. Melbourne Victoria. Australia or to the Secretaries of the National Committees of the I.U.C. or I.U.P.A.P. The Twelfth Annual Conference on Mass Spectro- metry and Mied Topics will be held in Montreal on June 7-12th 1964. Further enquiries should be addressed to Dr. N. D. Coggeshall Gulf Research and Development Company P.O. Drawer 2038 Pittsburgh Pa. A Conference on Industrial Synthesis and Applications of Organometallics sponsored by the New York Academy of Sciences will be held in New York on June 9-11th.1964. Further enquiries should be addressed to W. J. Considine Supervisor Organic Research M & T Chemicals Inc. Box 471 Rahway New Jersey. An International Conference on Physical Chem- ical and Biological Aspects of Photosensitisation in Solids will be held in Chicago on June 22nd-24th 1964. Further enquiries should be addressed to Professor L. Grossweiner Department of Physics Illinois Institute of Technology Chicago Illinois. An International Conference on Physics of Non- crystalline Solids will be held in Delft on July Cloth 1964. Further enquiries should be addressed to Dr. J. Schenk Secretary Laboratorium voor Technische Natuurkunde Lorentzweg 1 Delft The Net herlands.The Eleventh Ottawa Symposium on Applied Spectroscopy and Analytical Chemistry sponsored by the Analytical Chemistry Division of The Chemical Institute of Canada and the Canadian Association for Applied Spectroscopy will be held in Ottawa on September 9-1lth 1964. Further enquiries should be addressed to The Chemical Institute of Canada 48 Rideau Street Ottawa 2 Ontario. The Third European Symposium on Chemical Reaction Engineering will be held in Amsterdam on September 15-1 7th 1964. Further enquiries should be addressed to Ir. J. H. de Groot c/o Koninklijke/ Shell-Laboratorium P.O. Box 3003 Amsterdam The Netherlands. Personal.-The D.S.I.R. have awarded a grant of f10,630 to Prufessor R.M. Barrer of the Imperial 124 College of Science and Technology London for research on surface phenomena relevant to adhesion to tooth enamel and dentine. The Honorary Degree of Sc.D. has been conferred on Professor D. H. R. Barton by the University of Dublin. Dr. N. Beredjick formerly Principal Research Scientist Associate for the Ford Motor Company has been appointed to the United Nations Center for Industrial Development New York. Mr. M. G. Brown formerly of Nottingham University has taken up an appointment as a Lecturer in Chemistry at the University of Sussex. In addition he will have special responsibility for the Arts-Science scheme. Dr. A. W. Chapman Registrar of Sheffield University from 1944 to 1963 is to receive an Honorary Degree of LL.D.from the University in May 1964. Dr. K. CZarke has been promoted to Senior Lecturer in the Department of Chemistry at the University of Hull from October 1 st. The Title of Fellow of University College London has been conferred on Professor D. P. Craig. The title of Reader in Combustion Chemistry has been conferred on Dr. C. F. CuZZis in respect of his post at the Imperial College of Science and Tech- nology. Mr. H. B. Fraser has been appointed an Assistant Managing Director of Hercules Powder Company Limited. The title of Professor of Chemistry has been conferred on Dr. V. GoZd in respect of his post at King’s College London. Mr. R. W. GoZZedge has been appointed Senior Development Chemist of Algraphy Limited.Dr. M. Gordon Imperial College London has been appointed to a new Professorship in Chemistry at the Royal College of Science and Technology Glasgow from September 1st. Dr. G. Hallas has been appointed to a Senior Lectureship in Organic Chemistry at the Royal College of Advanced Technology Salford. Mr. B. Haynes is now Head of the Department of Chemistry at Kingston College of Technology. Dr. M. J. How has been appointed Lecturer in the Department of Chemistry at the University of Birmingham. Dr. K. H. Jack Research Manager Thermal Syndicate Limited has been appointed to a Personal Professorship in the Department of Metallurgy University of Newcastle-upon-Tyne from October lst with the title of Professor of Applied Crystal Chemistry.Mr. J. R. Jurratt of Boots Pure Drug Company Limited has been awarded the City and Guilds of PROCEEDINGS London Institute Insignia Award in Technology honoris causa. Dr. G. Jones has been appointed to a Senior Lectureship in Chemistry in the University of Keele from October 1 st. Dr. J. H. A. Leisten has been promoted to Senior Lecturer in the Department of Chemistry at the University of Sheffield from October 1st. Mr. A. W. Marsden has recently joined the Food and Agriculture Organisation of the United Nations to work in the Dairy Branch and to organise the F.A.O. International Meeting on Dairy Education to be held in Paris on June 2nd-8th 1964. The Title of Reader in Crystallography has been conferred on Dr.R. G. Mason in respect of his post at the Imperial College of Science and Technology. Dr. I. T. MiZZar has been appointed Reader in Chemistry in the University of Keelefrom October 1st. Dr. K. J. Morgan formerly of Birmingham University has been appointed Lecturer in the Department of Chemistry at the University of Lancaster. Mr. R. B. Moyes has been appointed to a Lecture- ship in the Department of Chemistry at the Univer- sity of Hull from October 1st. Dr. M. J. 7‘.Robinson has been appointed to a Lectureship in Organic Chemistry at St. John’s College Oxford from October 1st. Dr. P. W. SadZer has been appointed Head of Chemotherapy at Lilly Research Laboratories Limited Bromborough Cheshire. Mu.I. T. Smith Senior Research Officer at the Research Association of British Paint Colour and Varnish Manufacturers has been appointed Chief Research Chemist of the Epoxylite Corporation California. Mr. R. L. Stephens has been appointed Consultant to the Pharmaceutical Development Department of Philips-Duphar N.V. Holland. Dr. R. H. Thornson Senior Lecturer in the Department of Chemistry University of Aberdeen has been designated Professor of Organic Chemistry. Professor A. R. Ubbelohde has been elected a Corresponding Member of the Gottingen Academy of Sciences. Dr. A. F. Wells of Imperial Chemical Industries Limited Manchester recently delivered the Boomer Memorial Lectures at the University of Alberta Edmonton. The theme of the lectures was “The Third Dimension in Chemistry.” Dr.W.J. WheZan will be a Visiting Professor in Biochemistry at Iowa State University Ames Iowa U.S.A. during June and July. Dr. J. M. Winterbottom formerly of Laporte Chemicals Limited has been appointed Lecturer in Physical Chemistry at Nottingham and District Technical College. APRIL1964 125 FORTHCOMING SCIENTIFIC MEETINGS London Thursday May 7th 1964 at 6 p.m. A Discussion on Mass Spectrometry will take place in the Rooms of the Society Burlington House W.l. The following papers will be presented “Instrumentation and General Applications of Mass Spectrometry,” by Dr. J. H. Beynon. “Specific Examples of the Use of Mass Spectrometry in Organic Chemistry,” by Dr. R. I.Reed. (Abstracts of the Papers can be obtained from the General Secretary.) Thursday June 1lth at 6 p.m. Centenary Lecture “Applications of Optical Rota- tory Dispersion and Circular Dichroism in Stereo- chemistry,” by Professor C. Djerassi Ph.D. To be given in the Large Chemistry Lecture Theatre Imperial College of Science and Technology Imperial Institute Road S.W.7. [British Railways are offering concessionary fares (single fare plus one half for the return journey) for this meeting and a travel voucher will be sent by the General Secretary on receipt of a stamped and addressed envelope.] Birmingham Friday May Sth 1964 at 4.30p.m. Lecture “The Scientific Examination of Questioned Documents,” by Professor C. L. Wilson; Ph.D.D.Sc. F.R.I.C. Joint Meeting with the University Chemical Society to be held in the Chemistry Department The University. Cambridge Monday June Sth 1964 at 5.30 p.m. Centenary Lecture “Applications of Optical Rota- tory Dispersion and Circular Dichroism in Stereo- chemistry,” by Professor C. Djerassi Ph.D. Joint Meeting with the University Chemical Society to be held in the University Chemical Laboratory Lensfield Road. Glasgow Tuesday May 26th 1964 at 4 p.m. Centenary Lecture “Applications of Optical Rota- tory Dispersion and Circular Dichroism in Stereo-chemistry,” by Professor C. Djerassi Ph.D. To be given in the Chemistry Department The University. Manchester [Meetings to be held in the Lecture Theatre R/G7 Renold Building (Lecture Room Block) Manchester College of Science and Technology.] Thursday May 14th 1964 at 6.30 p.m.Official Meeting and Niels Bohr Memorial Lecture given by Sir George Thomson F.R.S. Thursday May 28th at 6.30 p.m. Centenary Lecture “Applications of Optical Rota- tory Dispersion and Circular Dichroism in Stereo- chemistry,” by Professor C. Djerassi Ph.D. Norwich Thursday May 14th 1964 at 5.30 p.m. Lecture “Solvolysis and Olefin Rearrangement,” by Dr. M. C. Whiting M.A. A.R.C.S. To be given in Lecture Room 2 The University of East Anglia Wilberforce Road. Nottingham Wednesday June 3rd 1964 at 5 p.m. Centenary Lecture “Applications of Optical Rota- tory Dispersion and Circular Dichroism in Stereo- chemistry,” by Professor C.Djerassi Ph.D. To be given in the Chemistry Department The University. Reading Tuesday May 19th 1964 at 5.30 p.m. Lecture “Some Recent Work on Clathrates,” by Mr. H. M. Powell M.A. F.R.S. Joint Meeting with the Royal Institute of Chemistry and the University Chemical Society to be held in the Large Chemistry Lecture Theatre The University. Sheffield Monday June lst 1964 at 4.30 p.m. Centenary Lecture “Applications of Optical Rota- tory Dispersion and Circular Dichroism in Stereo- chemistry,” by Professor C. Djerassi Ph.D. To be given in the Department of Chemistry The Univer- sity. Tees-side Friday May 22nd 1964 at 8 p.m. Lecture “Compounds of the Rare Gases,” by Professor C. A. Coulson D.Sc. F.R.S. Joint Meet- ing with the Royal Institute of Chemistry and the Society of Chemical Industry to be held in the Constantine College of Technology Middlesbrough.I26 PROCEEDINGS OBITUARY NOTICES THOMAS GIBSON PEARSON 1908-1962 THOMAS was born on January 28th GIBSON PEARSON 1908 and was educated at South Shields High School and Armstrong College Newcastle. There he graduated with First Class Honours in Chemistry in 1928 and was awarded the Ph.D. of Durham Uni- versity in 1931. He was subsequently awarded the D.Sc. by the University of London in 1938. His first academic post was a demonstratorship at Armstrong College (1920-30 1930-33) the academic year 1930-31 being spent at the Institut fur physikalische Chemie at Frankfurt-am-Main where he worked with the late Professor Bonhoeffer.He was appointed a Demonstrator in Inorganic Chemistry at Imperial College in 1933 and later became lecturer. This post was held until 1939 when he became Assistant Scientific Manager in the Central Scientific Depart- ment of the British Aluminium Company at Warring- ton. He stayed with this Company throughout the remainder of his scientific career becoming in turn Assistant Director of Research and in 1955 Director of Research at the new laboratories at Gerrards Cross. While at Armstrong College he was awarded the Saville-Shaw Medal of the Society of Chemical Industry (Newcastle section) in 1927 and held the Earl Grey Memorial Fellowship of Durham Univer- sity from 1930-31 when. he was in Bonhoeffer’s laboratory.Pearson published forty-four scientific papers the majority of which appeared in the Society’s journal. He was one of those who was fortunate enough to be initiated into the art of preparative inorganic chem- istry by P. L. Robinson with whom his first publica- tions appeared. They were a series of five papers on the polysulphides of the alkali metals and clarified the types of compound formed under a variety of preparative conditions. These were followed by other papers describing the preparation and properties of pure carbonyl selenide and selenophen and prepara- tion of carbonyls of lithium rubidium and calcium and a detailed study of the kinetics of the reaction between hydrogen and sulphur. All except that on the alkali metal carbonyls appeared jointly with P.L. Robinson and other co-workers as did other papers on the physical properties of hydrides. The year spent in Bonhoeffer’s laboratory intro- duced Pearson to an entirely new field the chemistry of short-lived radicals. With Bonhoeffer he made an experimental study of the dissociation of water vapour to hydrogen and oxygen in an electrical dis- charge as a function of current and pressure and was able to deduce the approximate half life of the OH radical and propose a mechanism for the reaction leading to the formation of hydrogen and oxygen. This type of work was followed up in Newcastle the first publication made with Robinson and Stoddard being in independent confirmation of Paneth and Lautsch’s work on the formation of free ethyl radicals on the pyrolysis of tetraethyl lead.Another related topic studied was the chemical reactivity of atomic hydrogen. In the course of this work the formation of bismuth hydride was confirmed though it was shown that the reported formation of lead hydride might have been associated with the presence of carbon compounds. The direct formation of hydrides of germanium tin arsenic antimony tel- lurium lithium sodium and potassium by reaction of atomic hydrogen with the element was also established. Pearson’s teaching duties at Imperial College were in the analytical laboratory and he was one of the few who met the high standard which is familiar to those who have been trained there. His research was concentrated almost entirely on the study of free radicals produced in photochemical reactions.He was the first to demonstrate conclusively that ethyl radicals were formed in the photolysis of acetone ethyl methyl ketone and diethyl ketone. The vapour of the ketone was steamed at low pressure through an irradiated quartz tube and the radicals were allowed to react downstream with mirrors of lead antimony and tellurium from which the correspond- ing alkyls were isolated. Next in collaboration with R. H. Purcell it was shown that free propyl radicals are produced under these conditions in the photolysis of di-n-propyl ketone. They were identif3ed by re- action with mercury and the isolation of n-propyl mercury bromide. This was the first direct proof of the transitory existence of a higher analogue of methyl and ethyl radicals.Methyl radicals were also shown to be produced in the photolysis of acetaldehyde by warming the metallic mirror and so avoiding its deactivation by deposition of polymeric material. This work was later extended by Pearson Purcell and Saigh to the detection of methylene radicals formed in the thermal dissociation of diazomethane and the photo- chemical dissociation of diazomethane and keten. They were detected by reaction with selenium or tellurium leading to the formation of seleno- or telluro-formaldehyde. As in all these experiments half-lives were measured and an abnormally long half-life was observed for methylene in presence of keten.Another interesting observation made in collaboration with Glazebrook was that the radicals APRIL1964 formed in the photolysis of di-isopropyl ketone underwent isomerisation and on reaction with mercury gave n-propylmercury. Some evidence was also obtained for the transitory existence of the acetyl radical in the photolysis of acetone and the formation of phenyl radicals on the photolysis of benzophenone was also established. Pearson’s decision to leave academic life in which he had been so conspicuously successful was regretted by all his colleagues but his association with the British Aluminium Company proved equally fruitful. He was able to make a quick and accurate assessment of a scientific problem and to translate his ideas into a detailed laboratory pro- gramme.His work included fundamental studies of the Bayer and electrolytic reduction processes and of many other problems associated with the aluminium industry. Inevitably little of this was published but the monograph which he wrote for the Royal Insti- tute of Chemistry on “The Chemical Background of the Aluminium Industry,” in 1955 and which he was revising at the time of his death is still a standard work in this field. Pearson’s death on December 29th 1962 at the age of 54 came as a shock to his many friends in the universities and in industry. His personality changed little as he grew older. He seemed always to engender a friendly and happy atmostphere in both his scientific and his social activities.He had however deeper qualities which those who knew him well soon learned to appreciate. Chief among these was his modesty. It concealed a first class scientific mind which made outstanding contributions to both pure and applied science. H. J. EMEL~US. FREDERIK SIXMA 1923-1 963 LEONARDUS FREDERIK JOHANNES SIXMAwas born at Amsterdam on February 5th 1923. He studied at Amsterdam University (193948) and received his Ph.D. cum Zaude on a thesis “Substitution in Aro-matic Compounds; the effect of temperature and catalysts,” as a student of Wibaut. In 1949 he was appointed Lecturer in Organic Chemistry in Wibaut’s Laboratory. After Wibaut’s retirement in 1956 Sixma was appointed to the new Chair of Physical Organic Chemistry.During his stay at Amsterdam University he further developed several of the ideas put forward in his thesis on aromatic substitution. He also em- barked on a series of investigations on the kinetics of ozonolysis of aromatic compounds as well as of the isomerisation of aliphatic halides. In all these fields he published many papers mostly in the Recueil des truvaux chiniiques des Pays Bas in the beginning together with Wibaut. Meanwhile he became more and more attracted by the problems and atmosphere of industrial re-search. In 1960 this led to his early retirement from Amsterdam University and his appointment as Research Director of the States Mines’ Central Laboratories ;his responsibilities with this Company were extended a year later when he became one of the Managing Directors of the Dutch States Mines.His continued interest in academic life and his great energy may be gauged from the fact that he was able to serve as an extraordinary Professor of Physical Organic Chemistry at Eindhoven Technical University since 1961. Notwithstanding his many scientific and organisa- tional duties he has also made valuable contribu- tions to chemistry in the Netherlands by his member- ship of several committees including that of the General Board of the Dutch Chemical Society and the Editorial Board of the Recueil. In February 1963 at the age of 40 a tragic traffic accident ended the brilliant career of one of the Netherlands’ outstanding organic chemists from whose characteristic versatility and intellect many further fruits might have been expected.E. C.KOOYMAN. ADDITIONS TO THE LIBRARY Scientific and learned societies of Great Britain a handbook compiled from official sources by the British Council. Pp. 222. Allen and Unwin. London. 1964. History of the Salters' Company. J. S. Watson. Pp. 161. Oxford University Press. London. 1963. Petroleum-chemicals industry present status and future trends. H. M. Stanley. (Royal Institute of Chem- istry Lecture Series 1963 no. 4.) Pp. 25. Chemical applications of the shock tube. J. N. Bradley. (Royal Institute of Chemistry Lecture Series 1963 no. 6.) Pp. 29. Earliest published writing of Robert Boyle. R. E. W. Maddison. (Annals of Science 1961,17 no.3.) Studies in the life of Robert Boyle F.R.S. Part 4. R. E. W. Maddison. (Notes and Records of the Royal Society of London 1963,18 no. 2.) Development of brewing analysis; a historical review. J. R. Hudson. Pp. 102. Institute of Brewing. London. 1960. Solvay l'entreprise industrielle 1963. Solvay & Cie. Brussels. 1963. Solvay:l'invention l'homme l'entreprise industrielle 1863-1963. J. Bolle. Pp. 176. Solvay & Cie. Brussels. 1963. NEWJOURNALS Carbon from 1963 1. Chemical Engineering Japan. (Kagaku K6gaku). Abridged edition in English from 1963 1. Izvestiya Sibirskogo Otdeleniya Akademii Nauk S.S.S.R. Seria Khimicheskikh Nauk from 1963. Macromolecular Syntheses from 1963 1. Progress in Physical Organic Chemistry from 1963 1. Change of titles Fermentnaya i Spirtovaya Promyshlennost 1964. Formerly Spirtovaya Promyshlennost. Annual Report of Sankyo Research Laboratories 1963 15. Formerly Annual Report of the Takamine Laboratory.