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Photolyses of N-Nitrosamides in Acidic and Neutral Media

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Photolyses of N-Nitrosamides in Acidic and Neutral Media PHOTOLYSES OF N-NITR OSAMIDES IN ACIDIC AND NEUTRAL MEDIA by Antonio Chun Hung Lee B.Sc., The university of British Columbia, 1958 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in the Department Chemistry ANTONIO CHUN HUNG LEE , MON FRASER UNIVERSITY April, 1967 B.Sc., The University of &ritish Columbia, 1958 in the Department of Chemistry 'Je accept this Thesis as conforming to the required standard. PARTTAL COPYRIGIIT LICENSE I hereby grant to Simon Fraser University the right to lend my thesis or dissertation (the title of which is shown below) to users of the Simon Fraser University Library, and to make partial or single copies only for such users or in response to a request from the library of any other university, or other educational institution, on its own behalf or for one of its users. I further agree that permission for multiple copying of this thesis for scholarly purposes may be granted by me or the Dean of Graduate Sttldies. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Title of Thesis/~issertation: Author: (signature ) (name ) (date) ii A13S11'ilACT 2hotolyses of several IT-i~itrosanides in acidic end neutral media were studied. .:he photochenical decomposition of J- nitrooanides was fouud to involve exclusively nitrogen-nitrogen bond cleavage of the 1:-nitrosarnide group in contrast to the pyrolytic decomposition which involved cleavage of the acyl nitrogen bond. in acidic media, photolyses of IT-nitrosanides led to the light catalyzed denitrosation of the N-nitrosanides by photo- elimiiiation of the [NGH] group with the forxation of allylidenimides. The alkylidenimides undervent secondary reactions to give the corresponding aldehydes. The photo- elimination products were identified as the 2,4-dinitrophenyl- hydrazones of the aldehydes. In neutral media, the primary photolytic process of ii- nitrosa.:iides was the,fomation of nitroso and anide radicals. The axide radical was found to abstract intranolecularly a hydrogen atom attached to the carbon atom in the 5-position # to give a $-carbon radical. This 5-carbon rzdicel then coupled rniJ~hthe nitroso radical to give a C-nitroso compound which either tautonerized to i'om oxiine or dimerized. Alternatively the arnide radiczl underwent elinination of an alpha hydrogen to give the alkylidenimide as an intermediate. iThe $-position was numbered in reference to the nitrogen atom o; the ar~idegroup. For exzmi~le,- - the for-.ula of 6-nitroso-n- 41 hexylf onamide would be CR3-CH2-F-CH2-CH2-CH2-:;H-$-;; N=O 0 iii In presenting this thesis in partial fulfillinent of the requireinents for an advanced uegree a-L the Sixon Fraser University, I agree that the Library shall make it fully available for reference and study. I further agree that permission for extensive copying of this thesis for schol- arly purposes may be granted by the Iiead of my Departraent or by his representatives. It is understood that copjing or publication of this thesis for financial gzin shall not be allowed without my written pemission. 2epartment of Chemistry .................................. The Sixon Fraser University aurnaby2, BOGo, Canada Date.................... I would like to express my sincere thanks and appreciat- ion to Dr. Y.L. Chow for his advice and encouragenent throughout this research. It is a pleasure to thank Drs. 'J.A. Ayer and D.D. Tanner of the University of Alberta for providing the mass spectra. The co-operation of Liss ?,I. 3ieser of this department in providing the n.m.r. spectra is deeply appreciated. 6 . Cyclohexylacetamide ............................ 8 7. Phenethylacetamide ............................. 8 8. N-nethyl-o-toluamide .......................... 8 9 . Benzylformamide ................................ 9 10 . 4-Phenyl-n-butylacetsmide ...................... 9 11 . ?ieserVs Solution .............................10 C . PHEPAMTIOWS GP N.TU'I'I'HOSAi.IIDES General Procedure for Kitrosation of Amides ....11 Preparations of h-nitrosoacetamides and N-nitrosoformamides ............................ 11 D . PKGTOLYSES IN ACIDIC XdDIA General Procedure of Photolysis in Acidic Ledia vi 'l'Ai3LI;S 01' CO?:T~5:'I'S (Cont Id ) Pa ge 4. N-nitroso-N-pheiiethylacetamide ...................17 5 . N-nitroso-IT-cyclohexylacetamide ..................18 uf . N-nitroso-N-n-butylformamide .....................18 E . PXOTOLYSdS IK UNJ'L'IUL I3ZDIA Generzl Procedure of Photolyses in IJeutral ; edia .. 19 4. N-nitroso-14-benzylacetamide ......................28 5 . N-nitroso-N-pheiiethylacetamide ...................29 6a . N-nitroso-N-methylcaproamide in n-pentane ........29 6b. N-nitrooo-N-methylcaproamide in cyclohexane ......31 6c . F-nitroso-3-methylcaproamide in petroleum ether ..31 7a . N-nitroso-X-methyl-o-toluamide in petroleum ether ............................................32 7b . N-ni$roso-N-methyl-o-toluamide in benzene ........35 8. Control Photolysis ...............................38 I11 . RESULTS Photolyses in Acetic Kedia .......................39 Photolyses in Xeutral Xedia ......................41 DISCUSSIONS Pliotolyses of lj-nitrosamides in Acidic Iiledia .....52 Photolyses of X-nitrosanides in Neutral +:edia ....54 SUGGESTIDIS FGR 3'U;iTIIER ~i'Sdb3CH .................60 BIBLIOGRAPHY .....................................64 vii Acidic Liedia ..........................................61 111. The l-'roducts of Pliotolyses of N-nitrosamjdes in Cliart s -Paqe I. The Therxal Decomposition of IJ-nitrosanide ............ 1 11. The Photocheinical Iiechanism of ?I-chloramides .......... 2 111. The Yhotochenical Rearrangement of IT-chlorimides ...... 3 IV. The Photolysis of Xitrite Ester in Xeutral Eedia ...... 3 V. Possibility of Generating Xitrogen 2adicals .from the Photolysis of 2:-nitrosanides in lleutral ILedia ......... 4 VI. Photo-elinination of [zc~]from I<-nitrosacine ......... 4 , VII. The Photolysis of N-nitroso-B-benzylacetm-ide in Neutral Iiedia ......................................... 40 VIII. The Photolysis of N-nitroso-N-n-hexyl2cetanide in Neutrl LIedizl and the iiydr01ysi.s of C-ilitroso Dir.er .... 43 IX. The Phot olysis of i!-nitroso-i~-4-~hen~l-n-&ut~laceta:?Iide in Keutral Lledia and the Formation of 2-cheiiyl- pyrrolidine ........................................... 45 X. The Cleavege of the ~-oximino-il-hesylfor~:~a~~i~eubon Electron Impact ....................................... 45 XI. The Photolysis of K-nitroso-W-phenethylco,cei;a::lciein Xeutrzl L!edia ......................................... 47 XII. The Photolysis of X-nitroso-3-nethylc8proan1ide ........ 4s viii Charts (Cont 'd) Pa ~e XIiI. The Photolysis of 1:-nitroso-N-methyl-o-toluanide in Xeutral Media ..................................... 51 XIV. Xechanism of the Photolysis of N-nitrosamides in Acidic Xedia ...................................... 53 XV. General .Photochemical Xechanisrn of N-nitrosamide in Xeutral Xedia .................................. 55 XVI. Possible Side Reaction of the Photolysis of Figure I. The n.m.r. Spectrum of Compound ;(;;";XI1............. 49 lTlie N-nitrosanides are characterized by a series of absorptions at 390-430 rnp in either polzr or non-polar solvents. They are thermally unstable. Their thermal stability is depend- ent on the structure of the parent amines (X group in conpound The 2:-nitroso-N-alkylamides were first pyepared by ?echmann (2) in 1894 and by Chancel (3) in 1895. Chancel and latter Peclunann(4) reported that the decomposition of bl-nitrosamides yielded esters, but neither studied the recction any further. E.H. 'Xhite (5) uindertook further study of the thermal decom- position of if-nitrossmides to esters in various solvents ranging from acetic acid to cyclohexane. On the basis of these studies, he proposed that N-nitrosamides rearranged to form intermediate diazoesters which underwent nitrogen elimination to yield the carboxylic ester. In this mechanism, the nitrogen-carbonyl bond cleavage took place as the first step (6). Chart I. The Thermal Decomposition of IT-nitrosamide. Although investigations of photochenically labile conpounds such as B-halamides (7), N-chloroimides (8) and alkyl nitrite esters (9) have been comprehensive, no work has been done on 2 the pilotolyscs of X-ixi Lrosmides. T - 2. S. Xeole , s .L, iiarcus and ii. G. Sclieperr: reported that -- A-ciiloro derivatives of both f!-methyl and N-t-butgl pentano- anides were rearranged upon irradiation to the 6-chloro isomers in benzene (7). The N-chloroamide rearrangements m-re found tobe a free-mdlcal chain process since the chloroaxidec re- arranged rapidly but only upon weak irradiation. The photo- chexical inechanism of X-~hloroa.~lideswas found to be as following. - Chart I1 The Photochemical ;.;echani.sm of Z-chloroznides- . 3.C. Peterson and A, '.'!anbs~ans (8) reported i~hota- chemical rearrzngenent of 3-chloroimides to 5-chloroinides. d IY Acyclic inidyl radicals such as (ZDOCB3 ) might rezrranse to X at rates Past enough to permit selective introduction 1 Bi <- - of functions1 groups at the 6-position of the inides. ?he 1;-chloroifiide3 VIII having primzry, secondary or 'oenzjilic hydrogen do 2f ford their 6-chloro isoaer when iyradizted in neutral organic meaia. Chart III The Photochemical Rearraju-;ement of 1:-chloroimides-.- . The photochemical generation of amide radicals from X-chloroamides and of irnide radicals from 2-chloroimides appear- ed to follow the same mechanistic pathway as the Barton . reaction (10). i'he Barton
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