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The Photochemistry of Tetramethyl-3-Thio-1,3-Cyclobutanedione

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The Photochemistry of Tetramethyl-3-Thio-1,3-Cyclobutanedione South Dakota State University Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange Electronic Theses and Dissertations 1972 The Photochemistry of tetramethyl-3-thio-1,3-cyclobutanedione Mason Ming-Sun Shen Follow this and additional works at: https://openprairie.sdstate.edu/etd Recommended Citation Shen, Mason Ming-Sun, "The Photochemistry of tetramethyl-3-thio-1,3-cyclobutanedione" (1972). Electronic Theses and Dissertations. 4833. https://openprairie.sdstate.edu/etd/4833 This Thesis - Open Access is brought to you for free and open access by Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange. It has been accepted for inclusion in Electronic Theses and Dissertations by an authorized administrator of Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange. For more information, please contact [email protected]. THE PHarOCHEMISTRY OF TETRAMETHYL-3-THIO-l,J-CYCLOBUTANEDIONE BY MASON MING-SUN SHEN A thesis submitted in partial fulfillment of the requirements for tne degree Master of Science, Major - in Chemistry, South Dakota State University 1972 SOUTH DAKOTA STATE UNIVERSITY LIBRAR fer -th:Ls -7 - - -- -07 -­ D;;;/:...; TO MY PARENTS PHOTOCHEMISTRY OF THE TETRAMETHYL-)-THI0-1,)-CYCLOBUTANEDIONE Abstract MASON MING-SUN SHEN Under the supervision of Professor James J. Worman photochemical reaction of tetramethyl-3-thio-i.l,3-cyclo­ The butanedione in the presence of oxygen and light yields tetramethyl-1, )-cyclobutanedione and sulfur dioxide. kinetics and mechanism of the reaction have been studied The thoroughly in different solvents and at different concentrations. Results this study indicate that the mechanism probably involves· of singlet oxygen and state thione although triplet thione and ground triplet xygen are not completely eliminated. o CONTENTS l. Introduction •••••••••••••••••••••••••••••••••••••••••••••�•••;••• 1 2. Purpose •••••••••••••••••••••••••••••••••••••••••••••••••••••••••• ? ). Results Discussion and I. The preparation and purification of tetramethyl-3-thio-l, 3-cyclobutanedione ••••••••••••••••••••••••••••••••••••••••• 8 II. The photocheiaical reaction of the monothione ••••••••••••••• 9 III. The rate of reaction and kinetic studies , ••••••••••••••••• �12 IV. The identification of the products •••••••••••••••••••••••••21 T mechanism reaction v. he of the ••••••••••••••••••••••••••••••23 Conclusions •• , •••••••••••••••••••••••••••••••••••••••••••••••••••30 4. 5. Experimental ;Description of instrumentation •••••••••••••••••••••••••••••••••••31 The preparation of tetramethyl-)-thio-1, 3-cyclobutanedione, ••••••32 The purification of tetramethyl-3-thio-1, 3-cyclobutanedione ••••••32 Photodesulfurization of tetramethyl-3-thio-1,3-cyclobutanedione,.35 The isolation of the tetramethyl-1, 3-cyclobutanedione,,, •••••••••38 The identification of sulfur dioxide . , ••••••••••••••••• , •••·• · ••••• J8 Desulfurization by singlet oxygen •••••••••••••. •••••••••••••••••••39 Fluorescence and phosphorescence spectroscopy••••••••••••••••••••40 Photochemistry of tetramethyl-1,3-cyclobutanedithione ••••••••••••4 1 The purification of solvents•••••••••••••••••••••••••••••••••••••41 6, Appendix•••••••••••••••••••••••••••••••••••••••••••••••••••••••••43 References•••••••••••••••••••••••••••••••••••••••••••••••••••••••51 ?. ----- TABLES Kinetic data for a first order reaction with an TABLE I initial concentration of 0.098 monothione 14 N •••••• •• Kinetic data for a first order reaction with an !ABLE II initial concentration of 0.075 monothione 14 M ••••••• • Kinetic data for a fir�t order reaction with an TABIE III initial concentration of 0.010 monothione 15 M •••• •••• Kinetic data for a first order reaction in the TABLE IV presence of cyclohexa.diene 15 •••• • ••••••••••••••••• ••• Kinetic data for a zero order reaction with an TABLE V initial concentration of 0.098 M monothione 16 ••••• ••• Kinetic data for a zero order reaction with an TABLE VI initial concentration of 0.075 M monothione 16 •••••••• Kinetic da"i:.a for a zero order reaction with an TABLE VII initial concentration of 0.010 M monothione 17 •••••••• Kinetic data for a zero order reaction in the TABLE VIII ene 17 presence of cyclohexadi ••••••••••• •••• • ••••••••• TABLE Summary of photodesulfurization of tetrainethyl- IX 3-thio-l, J-cyclo butanedione 37 •• • ••••••••• •••••••• •••• 1 INTRODUCTION first law of photochemistry, formulated in the works of The - Grotthus (1817) and Draper (1843) more than a century ago, states1 Only the light which is absorbed by a molecule can effective in be l producing photochemical change in the molecule . The law and its consequences are commonly taken for granted by photochemists today. the advent of quantum mechanics, the effect of light on matter Until not properly derstood.2. a result, during the prime age was � As � photochemis� (-1920) numerous and wondrous photochemical reactions ar � discovered , but both useful application of these results and _ were 3 1 formulation of a unifying theory were lacking. From 1920 to 950, photochemistry was perhaps considered the realm of the physical chemist 4 studied the details of photoreactions the gas phase • The who 1n availability of new spectroscopic and analytical techniques during the l950's to the present date and the development of imp�rtant theories concerning electronically excited states, reduced the difficuity in characterizing the complex products of photoreactions and gave promise of control of photochemistry2. In the last decade.the chemical literature to very large was a extent crowded with studies involving the controlled photochemistry of organic compounds,. particularly those containing carbon and hydrogen only. More recently many studies have been extended to those com- containing heteroa.toms such as oxygen, nit�ogen, and sulfur. pounds 2 The photochemistry of carbon pi bonded to unconjugated oxygen in 0 ud.ied1 ketones been exhaustively st • Similar st e on Azo­ has udi s methines (carbon pi bonded to nitrogen also ·been reported15. a ) have Although ce of photochemistry been done on compounds a rtain amount has containing the co ated thiones5, there n� documented reports njug are on the photochemistry of carbon pi bonded to sulfur i molecules n con ing system simple \.Ulconjugated chromophore. tain this as a The preparation and reactions of unconj'ugated docu­ thiones are mented elsewhere16 and in worlt it also been shown this has the l;J­ diphenyl-3-prepanthione (!) undergoes an accelerated dimerization ? presence of light to give the d.itheitane (2). in the (1) instability of its ability to·dimerize the The 1 and in it impossible to establish the reaction clear cut dark make as a photochemicaJ. phenomenon of the thiocarbonyl chromophDre. This accompanied by the fact that cyclohexanethione known to (.l) vas undergo dimerization by both ionic mechanisms6 and free radical prompted to·seek more stable thione. us a unconjugated hv O=s (�) In 1967 the synthesis tetramethyl-3-thio-l,)-cyclobutaned.ione of 8 reported is a bright ci-ystalline solid which, unlike · . '4\:!) was • -it red .o=(>=s <4)- 9 most other unconjugated aliphatic thiones , shows no tendency to polymerize ordinary temperatures, and is easy to dimerize or at very sublimes readily room temperature and has characteristic, handle, It at 8 somewhat camphoracious odor It is a very good compound.. to use • · photochemical studies the unconjugated thiocarbonyl chrom�phore for of do not have to worry complications of dimerization, because we about the hydrolysis, etc. The photochemistry of tetramethyl-1, 3-cyclobutanedione has (2) lO investigated thoroughly and therefore a base from been represents which to make comparison. photolysis of tetramethyl-1,J-cyclo- a The 4 by irradiation with ))6 light leads to a cl va.ge and butanedione run ea tetramethylcyclopropanone, further reaction produce forms will tetramethylethene11•12• co l-s¢propyl alcohol (5) It would realistic to e ect the photolysis of tetramethyl-3- seem xp thio-l,3-cyclo butanedione a lower light at 520 Q!) at wavelength or transition of the group, compare to the n�TT* nm (the �TT* C=S carbonyl group at )20 nm) to give transition of similar results. 0 H > -A+ o-Q=s cs 5 Another photochemical study on the carbon sulfur double bond which appeared in the recent literature is the photochemical reaction l of sulfines13, 4• Sulfines undergo a photod.esulfurization in the ---- hv ·-{ ----� [ - Sens. (0 0-0 ] " · C=o + SO. 2 / .' presence singlet oxygen. From this r action we also of might expect the photolysis of tetramethyl-J-thio-1,J-cyclobutanedione Q!) presence of oxygen and sensitizer to 'Wl.dergo a photodesulfuri- in the zation reaction as follows1 O=.Q=s+ 0.2 > (4) !' o=Q=o + .so (5) 6 . One could also expect dimerization to that reported of 4 si.'llilar · l to give unusual spiro compound. 2• for 7 the From the foregoing discussion it is evident that the.photo- of simple unconjugated thioca.rbonyl chromophore chemistry the has investiga.tion. In to understand more system avoided order of t.his undertook \investigation. we our PURPCSE project was undertaken in an attempt to increase our This ·-- knowledge·of photochemical. reactiQns about compounds containing unconjuga.ted thiocarbonyl chromophore. The ma.in areas the of those studied include the reaction mechanisms and interest and kineti stwlies of the photochemistry of tetramethyl-3-thio-1,3- . c lobutan on cyc edi e . c. 8 DISCUSSION RESULTS AND PREPARATION
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