DUHKHAHARANCHAKRAVARTI

Elected Fellow 1949

D~HK~AH~R&CHAKRAVARTI, an eminent scientist and a distinguished educationist was born in Calcutta on January 18, 1903. His ancestral home was at Kotalipara, a village in the district of Faridpur, now in Bangladesh. Son of Sri Jnanadakantha Chakravarti and Smt Tarangini Debi, he was brought up in an aura of ancient Indian culture, his father being a devout Brahmin and a renown2 sanskrit scholar. His early education started in a school of Kotalipara but soon he was transferred to Calcutta and was admitted into Sanskrit Colbgiate School where under the personal care and inspiration of Sri Benimadhab Das, the then Headmaster of the school? he developed his scholastic aptitude and stood first in the &latriculation Examination (1920) of undivided Bengal. In keeping up with the family tradition, he was admitted into Sanskrit College but later shifted to Presidency College, Calcutta to study arts. As fate would have it, he soon changed over to science in which he showed his brilliance by standing fifth in order of merit in the ISc Examination (1922) of Calcutta University. He graduated his BSc (Hons. in Chemistry) and MSc (Chemistry) degrees in 1924 and 1926 respectively with commendable distinction.

Ile started his research career under the guidance of Professor Rajendra Nath Sen in the chemical laboratories of Presidency College which was acclaimed as the most distinguished seat of learning at the time. There he csme in contact with other renowned Professors, like Dr Panchanan Neogi and Dr Anukul Sarkar. He also studied under the great Acl~aryaSir PC Ray and shared his affection and encouragement along with many of his famous contemporaries. In 1934, he was admitted to DSc degree of Calcutta University for his pioneering work on synthesis and reactions of benzo-2- pysones and benzo-4-pyrones. During this period, he served in various capacities : a research scholar of Government of Bengal (1927-1930), a part time lecturer of Calcutta Medical Institute (1931-1932), and a post- graduate Fellow, Calcutta University (1 932-1 933). He subsequently joined the Department of Pure Chemistry, Calcutta University in 1934, as a lecturer, n post he held till 1950. In 1950 by another turn of fate, he was appointed the Secretary, Council of Post-graduate Teaching in Science 8. I I.,._ I. ' .' /9

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Duhkhaharan Chakranarti

Tecllnol~gy, University of Calcutta. However, he continued post- graduate teaching and research in the capacity of an honorary lecturer and there was no perceptible break in his research activity. In 1954, he accepted the post of Registrar, Calcutta University and became a full-time administrator. With his fatherly attitude towards his subordinates and his love for the students and teachers, he soon earned the respect of one and all. He possessed a phenomenal nieinory for faces and names and was perhaps the only university officer who could call niost of the employees by their first names which endeared him to every body. As the Registrar of Cslcutta University, he was deputed by the GoveEnment of India to visit USA, UK, and Europe in order to study university administration. He utiliscd this opportunity to visit a ilumber of chemical laboratories in th~secountries anti wherever he went, he was given warm reception by his former students. In 1961, Dr Chakravarti was cllled back to Science College, Calcutta to hold the prestigious chair of Sir Rashbehari Gho sh Professor of Chemistry. With the aplomb of a great teacher, he accepted the challenge and reorganised himself for post-graduate teaching and research. Such ,was his depth of knowledge and grasp in/chemistry that he succeeded in establishing his own school of research once more with a group of enthusiastic young pupils. From 1966 till his retirement in 1969, he was the Head of the Department of Pure Chemistry and the Dean of Faculty of Science, Calcutta University. He co~itinueclhis research as a retired UGC Professor till his death.

RESEARCHCONTRIBUTIONS Professor Chakravarti, froin 1930 onwards, initiated his ow11 independent research on synthesis and reactions of benzo-2-pyrones (coumarins) and benzo-4-pyrones (chromones) which ultimately brought him glory and success. Working singlehanded, he published a series of distinguished memoirs and earned the coveted DSc degree of Calcutta University in 1934. He soon built up an active school of research in the Department of Pure Chemistry, Calcutta and carried out extensive research in beiizopyrone chemistry. His major contribution was the study of Pechn~annsynthesis of coumarins (benzo-2-pyrones) and Siinonis synthesis of chromones (benzo- 4 ,pyrones) from phenols and /I-ketonic esters with spe cia1 reference to the part played by condensing agents and the influence of substituents present in the two reacting species. He also developed his own method of synthesis of coumarins. The chemistry of benzopyrones was at that time being actively investigated by a number of Indian and British groups and Dr Chakravarti's contribution was universally acknowledged and appreciated. He was the natural leader in this field in India. With time, his interest extended to other fields and lie took up the isolation and structure deter- mination of natural products from a group of Indian plants (different species of Pmnus and ~~ru,;)).Towards the end, he and his associates carried out Biographical Memoirs

Friedel-Crafts reaction using acid chlorides derived from a few aliphatic dicnrboxylic acids and aromatic substrates specially polyhydric ~henols and their methyl ethers. Some bicyclic systems, useful intermediates for steroid synthesis were also prepared. However, the chemistry of benzo- pyrones, his first love, continued to be his favourite subject till the end of his life. He has nearly one hundred original research papers to his credit. A

borent pstron of Indian Chemical Society, he published nearly all of thein in the Society journals. He had a very fruitful and long research career extending over four decades and a half (1927-1972). A large number of young scientists were trained under his guidance who are now occupying responsible positions in education and industry. Late Professor PC Datta DSc, FNA and Dr PC Bagchi, both o'f Indian Association for Cultivation of Science, and Professor S M Mukherjee DSc, FNA, formerly of Kurukshetra University were among his distinguished research associates. A more detailed account of the research contributions of Dr Chakravarti and his collaborators is given below topic-wise and not necessarily in chronological order.

Synthesis and Reactions of Benzopyrones (Coumarins and Chromones) The occurrence of a large number of coumarin (benzo-2-pyrone) and chromone (benzo-4-pyrone) derivatives has prompted many scientists in India and abroad to develop new general methods for building up these ring systems. The most common synthesis involves the use of phenols (mono-or polyhydric) and a variety of ,@ketonic esters which condense to give co uinarins under the influence of sulphuric acid (Pechmann reaction) and to give chromones under the influence of phosphorus pent oxide (Simonis reaction). Chakravarti and his group (also Robertson and coworlters in England) have shown that the cyclisation is not as reagent-specific as assumed by the original workers. The two modes of cyclisation leading to two different ring systems are apparently controlled by two factors-the type of condensing agents and the reactivity of the aromatic ring as determined by the electronic nature of the substituents. Dr Chakravarti observed that while under Pe chmann' s condition coumarins are invariably formed, Simon is' method for chromone synthesis using phosphorus pentoxide is not of the ssme general applicability. From rigorously worked out data, he has formulated the following general rules. Those phenols which readily give coumarins with &ketonic esters in the presence of sulphuric acid also give coumarins and not chromones in the presence of phosphorus pentoside. Those phenols which give coumarins with sulphuric acid in poor yield or not at all furnish good yields of chromones with phosphorus pentoside. Furthermore, the chromone formation is facilitated by the introduction of halogen, nitro, and carboryl groups in the aromatic ring; conversely, the presence of these groups io the phenolic moiety exerts inhibiting effect on ,Pechmalln reaction for coul~larinsynthesis. 011 the other hand, polghydric phenols like resorcinol, phloroglucinol etc, which form coumarilrs readily respond to Pecli~na~liireaction inspite of the inhibiting substituents in the aromatic ring. Chakravarti et al. ha~ealso used many neutral, basic, anti acidic colldensing agents such as sodium acetate,, sodium ethoxide, hydrogen chloride,, boric anhydride, zinc chloride, phosplioric acid, and aluminium chloride in the above reactioils and observed that although coumarins do form in poor to raediun~yields in all exes, u~iderno circrunstances chromo~les are formed without the use o E phospllor us pelltoside which is thus unique in its behavionr. Although tliese observations are substantiated by ample esperi~nelitaldata, no mechanistic iuterpretatio u co nltl be given at the time. The nest iniportant coiltrihutioil in co iusiario chemistry from Dr Ckalcravarti's group is the development of a new method of general appli- c~bilityfor the synthesis of 3, 4-dialkylcoumarias which are not easily available by coi~ventionalmeans. Briefly stated, the method consists in preparing 0-hydroxyaryl alkyl ketones either by Hoescli reaction or by Fries' rearrangement of acylated phenols, liiethylatillg them to methylethers, and submitting the latter to Reformatsky reaction with esters of a-halogenated fatty acids. The hydroxyesters so formed are readily dehydrated with and cyclised to benzo-2-pyrone systeni by heating with either sul- phuric acid or hydrochloric acid. The Iollowing observations have been made in connection with the synthesis of coumarins by this method : (i) When there are alkyl substituents both in the wand b-positions of the intermediate cinnalnic acids(or in the P-position only, as shown in a later paper), cournarins are obtained in quantitative yield. (ii) In absence of any substituent in a- and P-positions or with only srtbstituent in a -positiou, no cyclisatioii takes place, the proctuct being exclusively trans cilii~amicacids (0-coumaric acids). Apparently for the stability o I the intermediate cinlia mic acids is the de cisire factor. The method thu.s could be used either for the preparation of coomarins or o-counlaric acid depending on the starting materials. Another method of preparation of o-coumaric acids by Cliakravarti et al, may be mentioned in this connection. During mercuration of coumarins, Sen and Cliakravarti have observect that while reactive co uinarins on treatment with mercuric oxide (yellow or red) or mercuric acetate undergo nuclear niercuration, coumarins having electronegative groups like nitro aldehyde, and halogens suffer ring cleavage to f urnis11 o-coumaric acids in good yield. In this manner, 5-1dtro-, 5aldehydo-. 5-iodo- 3, 5-dichloro- arid 3, 5- dibromo-o-coumaric acids have been prepared fro111 the correspoiidi~lg coumarins. The method also worlts for benzene and naphthalene-azo- o-coumaric acid. In collaboration with Professor RN Sen, Dr Cllakravarti synthesised a few interesting a zo-n~ethine dyes by condensing 6-aldehydo coumarin with aromatic mono - and di-arnines and with dyes like resaisiline which contalils an amino group. The same aldehyde liad been condensed with dimetliy- aniline and m-NN-die thylaminophenol to furnish triphenylmethane dyes a nd pyronine dyes respectively. In yet another publication. Dr Chaltravart i Biographical Afernoirs

$4 preparzd a series oE axo-dyes fro m 6-amino co umariu ar~tl studietl the aluochrornic and hypsochromic effect of the lactonic ring. In later period, Chaltravarti and coworlrers have worked out a modified method for the synthesis of 3-aminocounlarin wherein acetylglycine is condensed with salicylaldehyde in the presence of acetic auhydride and a trace of pyridine or piperidine to give 3-acetamiclocoumarin (an improven~ellt on a method of Pandya and Sodhi). Subsequently, a number of %amino- and 3-hydroxg-co nmarins substituted in the benzene ring were prepared with a view to study their bacteriostatic and fi~rgistaticproperties. Other contributions of Dr Chaltravar ti in henzopyro ne cl~emistry are (i) the determination of the structure ol halogenated phenols such as chloro- resorcinol and chlororesorcylaldellyde throllgh their conversion into co umarin derivatives and comparison wit11 2nthentic specimen of halogenated coumarins (substituted umbelliferones) ; (ii) the cleterminatioi~of the structure of 5-chlororesaceto phenorle and pro pio phenone through the reduction of the carb onyl grcup by Clemmensen pro cedure, condensation of the deoxy- products with ethyl acetoacetate (Pechmann reaction! and characterisation of the resultant conmarins ; and (iii) preparation of 2-styrylchromones by condensing 2-methylchromones with aromatic aldehydes (Heilbron et al.) and their subsequent utilisation in farther synthesis. Finally, mention may be made oI the dethiled study of Chaliravarti and hIajumdar on Kostanecki reaction using halogenatecl 2-hydroxy-aceto- yropio- and i~utyro-phenonesin order to find out whether the halogen atoms have any appreciable influence on the folanlation of chromones as tliey have in Sirnonis reaction. It may be noted that Kostanecki reaction is capable of furnishing both counlarin and chromone derioatives. The study shows no marked influence of halogens on the chromone ring formation. 111 colla- boration of Shall 1.1 al. Chakravarti has isolated co~m~arinderivatives during Kostanecki acylation of some o-hydroxyacetophenorles. Dr Chakravarti's contributio~~in benzopyrone chenii~tryhas, thus, beell both intensive slid extensive.

Isolation and CI~aracterisatiorz of Natural Products froua lndin~cPlurlts Since 1942 Dr Chakravarti and his coworkers investigated several Indian plants particularly the different species of Prunnas and Pyrus collected from Darjeeling district and ICashnlir. From the hark ol Prunus puddunz three crystalline products have been isolated and their structures ascertained. One of them is pudd umetin, a new flavone, another is a flavanone, sakuranetin, and the third is an isoflavone, pronasetin. Puddumetin is identified as genkwanin ('i-methylapigenin) and it is interesting to note that a flavone, an isoflavone and a flavanone have been isolated from the same plant. Traces of glycosides e.g,. salruri~l(glucoside of salturanetin) have also been detected. Other species such as P. acuminzto,P. nepalensis, P. triflora and P. undualata have also been investigated. The oil of P. undtcalntn seed cootairis a-elaeostearic acid which had been found for the first time in the genus Pnmuss* Chemical investigation of different species of Pyrus such as Pmpashia, P. communis, P. malus, and P. sikliimensis was carried out and in addition to two or three unidentified crystalline compounds friedelin, epi-friedelin, n-triacontane (a hydrocarbon) myricyl alcohol, and p-sitosterol were isolated. One of his research associate Dr Bhar isolated five furocoumarins from the seeds of Heracleum nepalense, four of which are identified as bergaptin, an isomer of bergasez, byakangelicin and allo-imperatorin. The last-named compound was already known as a synthetic product and isolated from natural source for the first time. Friedel-Crafts Reaction of Acid Chlorides Derived from Aliphatic Dicarbox~lic Acids with Aromatic Substrates During 1964-1 972, Chaliravarti and coworkers made an extensive study of Friedel-Crafts reaction using acid chlorides of aliphatic dicarb oxylic acids such as malonic, succinic, ghitaric, adipic, pimelic, suberic, azelaic and sebasic acids on one hand and mono-, di-, poly-hydric phenols, their methyl ethers and halogenated derivatives on the other. The reactions were carried out with anhydrous aluminium chloride using nitrobenzene or tetrachloro- ethane as solvents and furnish three types of compounds, their proportion depending on the nature of the acid clilorides and aromatic substrates. The major product in, most cases,, are diketones arising out of the condensation of one mole of acid chloride with two moles of aromatic substrates. When the para position of a phenolic compound is free, condensation always takes place at this point. If not, then aryloxyesters are formed generally. Other products are aryloalkanoic acids as a result of the condensation of one mole of the acid chloride with one mole of phenolic substrate. Interestingly, succinoyl chloride has been condensed with phenols in presence of aluminium chloride to furnish only aryloxyesters which have been submitted to double Fries' rearrangement to give 1, Cdiketones. A horde of 1,3,- 4, 4-, 1,s-, 1,1-, 1, 1, 9, and 1, lo-, diary1 diketones have been synthesised for the first time utilising this procedure. Some of the o-hydroxy diketones were found to give beautiful cl~elatedcompounds with copper (11) and nickel (111) and some are utilised for the synthesis of dichromones by heating with an acid anhydride and its sodium salt (Kostanecki-Robinson reaction). d4iliscellaneous Syntheses Substituted acetophenones like resacetophenones, respropiophenones, resbutyrophenones and their halogenated derivatives have been converted into 1,s-diketones by condensing them with methylene di-iodide in the presence of sodium ethoxide (intermolecular alkylation). Desosyllenzoin had similarly been converted into 1, 5-diketones. Cis ,&Decalone had been synthesised from 2-p-cyanoethylcyclohexanone by successive reactions with ethyl cyanoacetate, catalytic hydrogenation, 1, ' -.&;:.ye""'S , :-.,;y "' if' ' " , - , >< '.'.'. .Z"rnq, ,,,$ .:,:,f. :i-/*r ;', ,I ,j?+,, * ;"y ;. -2%. >:,;.? :;. ai;*?'::;y~?qgijp~,r~~ ' '. ,; L.& . I +. <.,,, s, f -5..$: ";-,;*-f .,.?. . ;"',=. ,, .:-:J ,$b?<- .' ;,- ,**~..;>I~$:~~&~~,,.:!:+: : i . .. I , $ , - gh$Tm;),, * :;?,'i, ..; . ;. , r* i I .:. . 1'i"p;.:, "q:':' , ~~ . .: . , s. : , ,.. 4',,,? >i,$&-,-,;&:,,r -, 5 .,,, 1.:; ' , .. .f.~. .. ,*<,, , ~,: ,:k,j~.5.:.,:-- 8: ,*. ' ..t. -. -, ! . . . ,*,. .,, c -. ;:+.; : . .q,.b 1. 5' . ,..>~. , .: ,. &.i 8 .i - i... . , .; c ' .', . , , .'- ,. 1 . . . - Biographical Memoirs

.:* 2 " hydrolysis and re-esterifi ca tion and cyclisation of the resultant cyclohenane- l-acetate-2-/9-propionate followed by hydrolysis. By an analogom series of reactions, a-methyl-cis-/?-decalone had been prepared. In another series of experiments, l-acetyl-2-methylcyclohex-1-ene had been converted into its Mannich base and then condensed with diethyl malonate. The pr oduct on intramolecular Michael reaction followed by hydrolysis and decar boxylation furnished 10-methyl-l -decal0 ne.

Professor Chakravarti won many academic distinctions and held important positions in numerous learned societies in his time. He was elected a Fellow of the Indian National Science Academy (then National Institute of Science, India) in 1949. His association with Indian Chemical Society was deep and long. He served the Society in the capacity of a Council Member, Honorary Secretary (1 949-1 954), and Honorary Treasurer (1 958-1 972). It was typical of this great scientist that he published almost all his papers in the Indian Chemical Society Journals. He was the Local Secretary (1943 and 1952) of Indian Science Congress in its sessions at Calcutta, its Treasurer (1957), Member of its Executive Committee (1951-1953), and its Council Member (1958). He officiated as its General Secretary for three months in 1952: He was the Honorary Treasurer, Indian Science News Association (1953-54) and its Council Member for many years. He was an elected Council Member, Vice-president, and Trustee Member of Indian Asso ciation for the Cultivation of Science, Calcutta for many years. Professor Chakravarti was one of the pioneers in the endeavor to teach science through mother tongue. He was entrusted with the difficult task of editing technical terms in Bengali for chemical science as a part of a programme initiated by illustrio us Dr Shyama Prasad M ukherjee. He played a very importadt role in a project of teaching science through Bengali under the leadership of Professor Charu Chandra Bhattacharya. He was actively associated with Bangya Vijnun Parishad founded by Professor Satyendra Nath Bose, FRS with the object of propagating science through Bengali. He contributed many scientific articles in the Parishad's magazine, Jmn-Vijmn. He was also an author of a book in Bengali, Ranjan Drabya published by Viswa Bharati.

Inspite of his deep commitment and involvement in scientific and social activities, Professor Chakravarti never failed in his duties to his family. His family was a very educated. Of his four sons,, one is a chemical engineer and two are PhD in Chemistry (Calcutta University). Of his four daughters, one is PhD in Chemistry and the other one is PhD in Anthropology, both from Calcutta University. His elder brother late Professor Chintaharan Chakramrti was a brilliant scholar in Bengali and Sanskrit and retired as a Professor of Bengali from Presidency College, Calcutta.

In Professol: Chakravarti one would find a very rare combination of an \ eminent scientist, an ideal teacher, a successful administrator, a benevolent social worker, a well-beloved colleague, and a loving father all blended to make a perfect man. He left for his heavenly aboda on 25, September 1972. His behaviour towards the students was extremely informal and affectionate and the students reciprocated with love and respect.

BIBLIOGRAPHY

(with sen R N) 6-Aldehyde-coumarin and dyes derived from it. J. Anz. chcm. Soc., 50, 2428. - (with $en R N) Alkali sulphonates of coumarin and Nitro-coumarin. J. Indian chem. Soc., 5, 433. 1929. (With Sen R N) Coumaro-a-pyrones. iba, 6, 793. (With Sen R N) Mercuration of coumarins. ibid, 6, 847. 1930. (With Sen R N) A new n~ethodof conversion of coumarins to ortho-coumaric acids. ibid, 7, 247. 1931. Synthesis of coumarins from phenols and P- ketonic esters. Part I. ibid, 8, 129. - Synthesis of coumarins from phenols and /?-ketonic esters. Part 11. ibid, 8, 407. - Benzene and naphthalene-azo-o-coumaric acids. ibid, 8, 391. - The effect of lactonic ring on the colour of azo-dyes. ibid, 8, 503. Synthesis of coumarins and chromones-A preliminary note. ibid, 8, 619. 1932. Synthesis of chromones. Part I. Condensat ion of halogenated phenols with alkyl aceto-acetic esters. ibid, 9, 25. - Synthesis of chromone5, Part 11. Condensat ion of nitrophenols with alkyl aceto-acetic esters. ibid, 9, 3 1 . Synthesis of chromones. Part 111. Condensat ion /?-naphthol with alky 1. aceto- acetic esters. ibid, 9, 389. 1935. Meruration of coumarins (A note). ibid, 12, 139. - Synthesis of coumarins from phenols and ketonic esters, Part 111. ibid, 12\, 536. - (With Ghosh B N) Synthesis of counlarins from phenols and ketonic estars part IV. ibid, 12, 622. - (With ahosh B N) Synthesis of coui~larinsfrom phenols and ketonic esters. Part V. ibid, 12, 791. 1936. (With Banerjee B C) Synthesis of coumarins and chromones from halogenated and nitro-mesols. ibid, 13, 619. - (With Bagchi P N) Synthesis of coumarins and chromones from 4- chloro and 4-bromo-1 -naphthol. ibid. 13, 649. - On the limited applicability of kostanecki9s reaction. ibid, 13, 659. 1937, (With Banerjee B C) On the constitution of nitro-p-methylumbelli-ferone etc. ibid. 14, 37. 1937. (With Shah R C et al.) PechmannYs condensation of methyl$-resmcylate and 0-esorcylic acid with ethyl acetoacetate. J. Indian chem. Soc., 14, 71 7. - (With Mukherjee S M) Synthesis of coumarins from phenols and acetoacetic esters. Ccnst itution of halogenated resorcins and orcins. ibid, 15, 1 36. 1938. (With Majumdar B) Synthesis of coumarins from o-hydroxy-aoylakryl ketones, Part I. J. ibid, 1, 136. - Condensation of resacatophenone with ethyl acetoacetate. Sci. i& Cult.. 6 224' - (With Majumdar B) Synthesis of coumarins from o-~~drox~ar~lalkyl ketones. ibid, 4, 1. 1939. (With Chakravarti N) Constitution of halogenated resaceto and pro- piophenones. J. Indian. chem. Soc., 16, 144. Synthesis of cou~narinsand chromones. Proc. natn. Inst. Sci., India., 5, 235. - (With Majumdar B) Synthesis of couinarins from o-hydroxy-arylalkyl ketones Part 11. J. In'dian chenz. Sac., 16, 389. (With Dutta J) Synthetic experiments in the prone series. Part I. ibid, 16, 639. A (With Majunldar B) Limited application of Kostanecki reaction. Influence of halogen atom. ibid, 16, 151. 1940. (With Datta N L) Synthesis of counlarins from 0-hydroxy-aryl-alkyl ketones. Part 111. ibid. 17, 65. Barbiturates as hypnotirs. Indian East Chemist., 32, 227. (With Ghosh R P) Isolation of a new flavone from the bark of Prunus puddum. Sci. Cult., 8, 463. 1942-43 (With Bhar C N) Isolation of a new isoflavona from the bark of Prunus puddum. ibid. 8, 498. - (With Momen S A) Synthesis of coumarins from o-hydroary arylalkyl ketones. Part TV. J. Indian chern. Soc., 20, 338. 1944. (With Bera B C) Synthesis of coumarins from o-hydroxy-arylalkyl ketones. Part V. ibid, 21, 44. - (With Befa B C) Synthesis of coumarins from o-hydroxybenzophenones. ibid, 21, 109. - (With Ghosh P) Crystalline components of the bark of Pru~~sPuddum. Part I. ibid, 21, 171. 1945. $With Ghosh R P) Crystalline conlponents of the bark of Pvunus pudduitz, Part 11. ibid, 22, 301. 1947. (With Bhar C N) Crystalline components of the seeds of Heracleun~nepalense. Sci. & Cult., 12, 504. - Synthesis of quinine (Areview) ibid, 11, 232. 1948. (With Kundu N and Ghosh R P) Crystalline components of the bark of Prunus puddum. Part 11. J. Indim chem. Sac., 25, 329. - Chemical investigations of tli3 bark of Prunus acunzunata. Sci & Cult., 14, 35. (With Bhar C N) Crystalline components of the seeds of HeraeZeum nepalense. J. Indian. chenz. Soc., 25, 139. 1950. (With Sen B N) A note on the isolation of sakuranin. ibid, 27, 1.48. - (With Momen S A) Chemical investigation of the bark of Prurrus nepalonsis. -. . Sci. & Cult., 15, 329. 1961. Synthesis of isoflavanones and isoflavones. ibid, 27, 407. 1962. (With Raychaudhuri K P) Synthesis of 8-decalone. ibid, 28, 81. - (With Raychaudhuri IC P) A new synthesis of 10- methyldecal-{-one. Ibw 28, 245. - Synthesis of isoflavanones and isoflavones. ibid, 2 8, 242. D~hkhaharanChakravarti . . 1962. -(With-Ray~ha~dhuriK P) Synthetic investigations on fused ring compounds, Part I, J. Indian chem. Soc., 39, 391. 1963. Condensation of o-Hydroxy acetophenones with Inethylene iodide. Sci. & Cult., 29, 144. - (With Chakravarti N) Condensation of substituted acetophenones with methylene iodide. ibid, 40, 957. - New isoflavones. ibid, 40, 601. 1964. (With Roy N K) Condensation of subst it uted acetcphenones with met hylene iodide. 11. ibid, 41,65. - (With Roy N K) Chemical investigation of Pyrus pashia . Ham. ibid. 41, 83. - (With Roy, N K) Studies on delta- and epsilon-ketonic acids. Sci. & Cult.

-. (With Chakravarti N and Samanta S) Chemical investigation of pyvus communis Linn. J. Indian chem. Soc., 41, 859. 1965. (With Das R) Preparation of some new sulpl~anila~nido-coumarins. Sci. & Cult., 31, 27. - (With Chakravarti N and Sanlanta S) Studies in ~riedel-crafts reactions. ibid, 31, 191. - (With Dutta S P and Mitra A K) Modified lnethod for the synthesis of 3-anlinocoun~arin. Curr, Sci., 34, 177. - (With Roy N K) Condensation of and anhydride with phenols and phenolic ethers. J. Indian chem. Soc., 42, 607. - (With Chakravarti N N and Chakravarti A) Chemical investigation of Pyrus maZus. ibid, 42, 573. (With Sarkar U and Chakravarti A) Condensation of illalonic acid with phenols and subtd, phenols. Sci. & Cult., 31, 530. 1966. (With Chakravarti A) Chemical investigation of Prurzlcs triflorn. J. Indian ckem. Soc., 42, 65. - (With Roy J K and Barua A K) Triterpenoids. Entagenic acid. Sci. & Cult., 2'0, 199. (With Roy N K) Chemical examination of the seeds of Prunus undulata. Indian J. appZ. Chem., 27, 1. (With Roy N K: and Chakravarti A) Condensation of with phenols & phenolic ethers. J. Indian chem. Soc., 43, 32. (With Chakravarti A) Condensat ion of dicarboxylic acid d ichlorides with phenols. $ci & Cult., 32, 591. - (With Sarkar U) Synthesis of dichromones. ibid, 32, 592. 1967. (With Roy N K ef al.) Condensation of succinoyl chloride with phenols : synthesis of 1,4-diketones. J. Inla7ian chem. Soc., 44, 463. - (With Chakravarti N and Samanta S) Condensation of glutaroyl chloride and glutaric anhydride wit11 di-and polyhydric phenols. ibid, 44, 457. 1969. (With Saha M) Condensation of dicarboxylic acid dichlorides with di-and polyhydric phenols etc. Sei. & Cull., 35, 333. - (With Chakravarti A) Condensation of pimeloyl chloride and with phenols and phenolic ethers. J. Indicf~zchem. Soc., 46, 351. (With Chakravarti A) Condensatioll of azeloyl chloride and sebasoyl chloride with phenols and phenolic ethers. ibid, 46, 743. 1970. (With Saha M and Baral A K) Cu (11) and Ni (11) Chelates of some o-hydroxy diketones as Ligands. ibid, 47, 937. 1 - (With Das R an'd Bhattacharya S) Synthesis of new 3-subst ituted coumar ins of possible pharmacological value. Sci. & Cult., 36, 371. 1971. (With Saha M) Condensation of pimeloyl chloride and subeoyl chloride with phenols and their methyl ethers etc. J. Indian chem. Soc., 48, 209. - (With Bhattacharya S and Das R) Chemical investigation of Py~s sikkimensis ibid., 48, 297. - (With Das R) Synthesis of 3-substd. coumarins, Part 1, ibid., 48, 371. - (With Das R and Chakravarti S) Synthesis of 3-substd. coumarins. Part If. ibid., 48, 375. (With Das R) Synthesis of some biochemically important 3-amino-coumarins. Sci. & Cult., 37, 58. ( With Saha M and Chakravarti S) Condensation of glutayl, pimeyl, subeyl, azeloyl and sebasoyl chloride with aromatic hydrocarbons. J. Indian chem. SOC., 48, 1003. (With Chakravarti A and Sarkar U) Condensation of malonic acid with phenols and substituted phenols. ibicd., 48, 1017. (With Saha, M and Das R) Applicability of Kostanecki Robinson reaction to some o-hydroxy diary1 diketones. ibid., 48, 765. - (With Das, R and Saha M) Studies of some reactions on 3-hydroxy-6- chlorocoumarin. ibid., 48, 853. 1972. (With Saha M) Condensation of azeloyl chloride and seiasoyl-chloride with di-and polyhydric phenols etc. ibid., 49, 273.