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The Migration of Acyl Groups in Ortho-Aminophenols

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The Migration of Acyl Groups in Ortho-Aminophenols Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1948 The iM gration of Acyl Groups in Ortho- Aminophenols. Edgar Dumont Smith Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Part of the Chemistry Commons Recommended Citation Smith, Edgar Dumont, "The iM gration of Acyl Groups in Ortho-Aminophenols." (1948). LSU Historical Dissertations and Theses. 7912. https://digitalcommons.lsu.edu/gradschool_disstheses/7912 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. tm moBmoH of acyl okcups XH o-ASiISOFOTIOL£? A Dissertation Submitted to tm Cra&uate Faculty of the Louisiana State University and A gricultural axid 2,leehaaaical C ollege in partial fulfillment of the requirements for the &©gres of Doctor of Philosophy in the Department of Chemistry by adgar Dumont Smith B*D*, Tulan© U n iv ersity , 19D& &*&•» i’ulauo University, lb41 ^ a y * 1^46 UMI Number: DP69290 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMI Dissertation PublisNng UMI DP69290 Published by ProQuest LLC (2015). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106 - 1346 £he autiior wishes to eat pr ass M s gratitude to p* • L* LeRosen, who suggested and guided tU s Investigation, for Ms unfailing interest and many helpful suggestions* i t t m m o f r n m w m £* XHSaOBOCflOB •»«••»«•••••«•«•»« 1 IX* PJ5VIEW oy THE Uffi&ittUHS ««*•»*«•* * * . 4 m « TaaoaaricAL A* M igrations during second a c yla tio n * * • • i& 3* Migration in acid»typ« solvents • • • • • *16 C* M igration during hydrolysis ********18 2, Stability of sulphonyl derivatives « * * • 20 E* iforstation of bensoxazoloaes •«••••» *&X if* Heplaeement of acyl group *&2 IT * ^LPSaiMESTAL A* Preparation of acyl derivatives * * • * * *£5 3* Analysis of isomerisation mixtures * * * * 31 0# Hydrolysis o f mixed ortho d lacy la * * * * *33 Dm Analysis of hydrolysis mixtures ***** *33 T* EI3GUS2UOH OP H33ULT3 ••*•*«•••«*•* 39 v i. someae* •••***•*•«•*•*•*•«•• 58 T i l * SELECTED 3I&UOailAP2nf **•#»«*•«*•• * 6 1 T i l l * VITA *•«•**.*••**•*•*•*•«• *71 ill L im OF S A B I® X* Acyl Derivatives Studied »•••••••••« 26 XX* 'oialysia o t Ortho Mixed T iacyls •*#**+» * 4 8 III* Analysis of Alcohol Xsomerijsat ion products • • 60 I?* E ffe c t o f Heat on Pure Mixed Matey Is * • * * « 51 V* Analysis of Pyr id in# Isomer Isatiou Products * * 52 VI* Analysis o f Mixed Di&cyl flyd ro ly s is Products * 54 Iv u s *? o f n c a a a s lm U ltr a V io le t Spectra o f ^onoac^rl B a riv & tii rm « * • 42 II* Ultra Violet Spectra of l;iaoyl JBerivativos « * • « 43 v o s t i u m x considerable aiaount o f axperim ental data has been co llected 0 8 the general subject of acyl migrations in o-amioopfraaoIs since interest was f ir s t drawn to this problem by t m eminent .imarioan chemist* Julius stieglitas* in 189IU Tna groat majority of tala work has indicated that when two different acyl groups# derived fro® carboxyl Ic acids# are introduced into an o-aial no phenol the sum# @ixed diacyl derivative was generally obtained# regardless of tbs order of introduction* On hydrolysis the heavier acyl group has usually boon found on nitrogen# and in only a f m instances have fix tu re s o f the two possible monoaoyls been obtained* fas structure of the mixed diacyl derivatives has never boon proved# it generally being assumed that the group which was hydrolysed off by the actios ©f algali was the one attached to oxygen in the mixed d ia c y l* 'This work was undertaken because it was believed ta&t tae present availability of two powerful new tools of organic chemistry# chromatography and ultra violet spectrophotometry* might make it possible to isolate and identify the mixed diaoyl isomers if both were produced# to q u a n tita tiv e ly account fo r a l l o f tne products of t-ie reactions* 3y chromatographing the crude products of the acylatlons it was found that# In the specific instance Investigated here of v i acetyl-b«s*oyl dmrivstlvss o t o—aminophono 19 two mixed d ia e y l derivatives war# present in both crude product# which, however, were predominantly &-acetyl~0~bensoyl md &»& ansoy l*»o-aoe tj 1 o-amino phenol dependlag on the aoylat ion sequence* Acetylation of G^henseylsminophenol gave 62 percent of the unrear ranged M-benzoyi-O-acetyl form* while benzoyl&tion of o-acety larei nopneno 1 gave 91 percent of the usraarrshged isomer* Both of these pure mixed dtacyls were Isolated for the first time la this work, and their physical properties and relative stabilities under the influence of several factors was studied* the s tru ctu re o f these two isomers was proved by the cosspar- iscas of the ultra violet light abaorbtion of these compounds with the absorption characteristics of the corresponding para derivatives wherein the orientation of the acyl groups is well known* This work constitutes the first good evidence for the structure of these mixed d ia c y ls . I t has been demons! rated th at the ”161. r a t ions” which have been observed in acyl derivatives of o-eminophenol are, in reality, Isomer 1 sat ions of the normal form of the d!;*oyls under the c a ta ly tic in fluence o f the solvent media employed* I t was shown, by means of a combination of chromatographic separations and u ltra violet spectrophotometry, that in alcohol and pyridine solutions equilibrium mixtures containing 85 percent ani 77 percent of tae more stable H-aeetyl-O-benaoyl form of the mixed diaoyls were pro­ duced, respectively* It was pointed out that taese isomer is at ions v i i in alcohol are probably the axplan&tion of the conflicting data reported in the literature on these mixed diueyl derivatives, Water and heat also served to isomer lse these dlacyla, while benzene, hexane, acetone, ethyl stuer, *md dioxnne were much lees effective, if not inert, In this respect, finally it was shown in this study that hydrolysis of either of the two isomeric aoetyl-bensoyl derivatives of o-aminophenol in aqueous NaOR did not result in a single monoacylated product as has been report®! in the literature# Instead, it was found that th'88 hydrolyses produced a mixture of the raonoaoyls contain-, lag about 62 percent ©-benzoylaminophenQl and 3© percent o~a,cetyl~ asiinophenol regardless of the composition of the mixture of diacyls which was hydrolysed* The variations in composition of the hyd­ rolysis products, while slight, indicated that the greater toe proportion of the if-beHsoyX-o-acetyX mixed diacyl in the mixture hydrolyzed, the greater was the amount of ©-benzoyl ami no phenol produced* Comprehensive theoretical explanations of the results discussed above have been proposed which are based on modern concepts of organic chemistry and involve the so-called "resonance” and "inductive** effects in the molecules concerned* A new principle has been devel­ oped for predicting which of two isomers should be the more stable# This principle has been called "the principle of mlnicsuffl charge concentration" and states that the isomer having the greatest conc­ entration of positive charge at a point within its molecule, w ill v i l i be the mov0 unstable form* St is anticipated that tliis principle w ill prove useful la the furthar development of the theories of organic reactions* A surrey of the literature os these acyl lul^ratlcas has shows the preseat theory to he consistent with the reported results, but due to the nosw^uastitatlve nature of the woric reported is the literature, much of this work must he repeated &Xon$ the lines laid hows is this research before the theory can be fully tasted* 1st XHfBODOCfXOM The majority of reported work in this field ho® indicated that when two different acyl groups* derived fro® carboxylic acids* are introduced in to an o-assino phenol* g e n erally tm same mixed diacyl derivative is obtained regardless of the order of introduction of the two acyl groups* Ibis result has keen interpreted m meaning that a rearrangement has taken place during one o f the second acyl at ion processes* Os hydrolysis of the mixed diacyl derivative usually only one mono- aeylatad product could be obtained* and most of taa workers in this field have assumed that the group widen was hydrolysed o ff of the mixed diacyl under the influence of alkali* was toe group attached to oxygen in the mixed diaoyl derivative* \ few workers* however* have postulated the possibility of a rearrangement occurring during the hydrolysis stop* ifo satisfactory general explanation of the above exper­ im ental observations yet been proposed although attempts nave been made to explain t ne apparent migrations on the basis o f such varied faotors as the r e la t iv e acidity of the acyl groups {39* 51}* the relative weight of tne acyl groups (34* 35}* and the sturlo effects present in the molecules involved (3S* 3?}* The interpretations of organic re&otions now generally 1 z accepted are based largely <m Uia intuitive deductions of the h s g lis h cusm isis L&pworth* Robinson and Ingold {X£JhQ~i$34)as elaborated on tne basis of mra recent physica-ehetaioal findings* and in the light of the ooacupt of resonance in organic mol- ecu1os.
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