摘要:

Except fort-butyl chloride, the 1- and 2-methyl substituted ethyl chlorides reacted at ambient temperatures with clean titanium surfaces to produce mixtures of the corresponding alkanes and alkenes;t-butyl chloride gave only isobutene. At elevated temperatures (80–150 °C depending on reactant) the branched alkyl chlorides underwent clean, catalytic dehydrochlorination on hydrochlorinated titanium films to give gaseous olefin and hydrogen chloride, in contrast to the previously observed dehydrohalogenation ofn-alkyl halides, where metal was consumed continuously in a non-catalytic fashion.The kinetics of the dehydrochlorination were exceptionally simple and reproducible for a heterogeneous reaction and all reactions were first order in reactant. The reactivity order wast-butyl >i-propyl > neopentyl >i-butyl (ca. 106:6:3:1). Although a slight dependence of activation energy on reactant pressure was observed, all reactants gave a limiting activation energy of 15.5 ± 0.5 kcal/mol and the large variation in activity is attributed to differences in the Arrhenius pre-exponential factor.It is proposed that the non-catalytic and catalytic dehydrohalogenation reactions proceed by different mechanisms, the former via a dissociative chemisorption of the carbon–halogen bond and the latter via a concerted, surface-assisted HCl elimination.

ISSN:0008-4042    

DOI:10.1139/v72-350

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The rate of solvolysis of ethyl trifluoroacetate has been investigated in a series of H2O/D2O mixtures at 9.97 °C. The secondary isotope effects related to the hydrolysis of the isotopic pairs, methyl/methyl-d3, ethyl/ethyl-d5,i-propyl/i-propyl-β-d6andt-butyl/t-butyl-d9trifluoroacetates have been established as well as the temperature dependence for the hydrolysis oft-butyl trifluoroacetate. The significance of all these measurements with respect to the mechanism of these reactions is discussed.

ISSN:0008-4042    

DOI:10.1139/v72-351

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The reactions of the ligandsL′ = (CH3)2As, (C6H5)2P;n = 4, 6, 8; but not all combinations) with iron carbonyls are described in detail. The nature of the products is discussed as a function of the reaction conditions and the ligands. The mixed ligands yield eight different types of complexes which have been characterized. Two of these types (L—L′)2Fe2(CO)4. and (L—L′)2Fe(CO)3were previously unknown.

ISSN:0008-4042    

DOI:10.1139/v72-352

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Attempts were made to achieve new syntheses of the penicillin ring system by effecting the transannular cyclization of 3D-carbomethoxy-N-chloro-2,2-dimethyl-5-oxoperhydro-6L-phthalimido-1,4-thiazepine sulfone. However the products obtained were those resulting from ring cleavage and elimination reactions.

ISSN:0008-4042    

DOI:10.1139/v72-353

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The action of various bases on the three hexuronic esters, methyl (methyl 2,3,4-tri-O-methyl-β-D-glucopyranosid)uronate (12), methyl (methyl 4-O-methanesulfonyl-2,3-di-O-methyl-β-D-glucopyranosid)uronate (13), and methyl (methyl 4-O-acetyl-2,3-di-O-methyl-β-D-glucopyranosid)uronate (14), leading to elimination of the 4-O-substituents and formation of methyl (methyl 4-deoxy-2,3-di-O-methyl-α-L-threo-hex-4-enopyranosid)uronate (15) has been studied. It is concluded that effectiveness of 4-O-substituents as leaving groups is in the sequence, methanesulfonyloxy > acetoxy > methoxy.

ISSN:0008-4042    

DOI:10.1139/v72-354

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

cis- andtrans-5-Acetoxy-7a-nitro-5,7-dihydroindane are formed as well as the 4- and 5-nitroindanes when indane is reacted with nitric acid and acetic anhydride. These adducts both decompose on standing by loss of nitrous acid forming 5-acetoxyindane. Thecisisomer is obtained in greater amount and it undergoes elimination less readily than thetrans.

ISSN:0008-4042    

DOI:10.1139/v72-355

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The photolysis of 2-propanol vapor in the 1800–2000 Å wavelength range has been investigated. The volatile products of the reaction and their quantum yields at 80 °C and 200 Torr substrate pressure are H2(0.64), CH3COCH3(0.34), CH4(0.39), CH3CHO (0.29), CO (0.15), and C2H6(0.08). A mechanism is proposed that accounts for the observed rate variations with substrate pressure, exposure time, temperature, and pressure of inert addend. Acetone and acetaldehyde undergo significant secondary decomposition and this is the source of CO, CH4, and C2H6. Acetaldehyde is formed in the unimolecular decomposition of C3H7O radicals produced in the primary process.The effects of CO2and CF4as inert addends have been examined and it has been established that the quantum yield enhancement through collision induced predissociation that has been reported to occur in methanol is not a characteristic of the 2-propanol photolysis.

ISSN:0008-4042    

DOI:10.1139/v72-356

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The hot tube pyrolysis of dehydroabietic acid (1) at 400–500 °C was found to produce as major products the three possible A-ring olefins (19-norabieta-4,8,11,13-tetraene (2); 19-norabieta-4(18),8,11,13-tetraene (3); and 19-norabieta-3,8,11,13-tetraene (4)) resulting from the elimination of the carboxylate moiety. The i.r., n.m.r., u.v., and mass spectrum of each olefln was obtained and discussed. The pyrolysis of abietic acid (7) and levopimaric acid (8) under identical conditions was found to yield A-ring olefins; to isomerize to yield varying mixtures of palustric,7, and neoabietic acids; to dehydrogenate to yield1; and to eliminate propylene to form deisopropyldehydroabietic acid (15). A mechanism to explain the formation of15from the dienoic resin acids is given.

ISSN:0008-4042    

DOI:10.1139/v72-357

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The rate constants for the forward and reverse components of gas phase reactions:were measured with a pulsed electron beam, time resolved detection high pressure mass spectrometer at 300 °K. O2, Ar, and He at pressures from 1–7 Torr were used as third gas M. The forward reactions were found to be third order and the reverse reactions second order. Establishment of the equilibria could also be observed.

ISSN:0008-4042    

DOI:10.1139/v72-358

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The thermal decomposition of 1-alkyl-3-benzoyl-2-(m-nitrophenyl)aziridines in dry acetonitrile results in a series of autocatalytic hydrolytic cleavages, 1,3-dipolar additions, condensations, and rearrangements to give products including oxazolidines, 1,2-dihydropyrazines, pyrrolo-[3,4-d]-4-oxazolines, and α-aminoketones. The marked differences in product type and distribution fromcis- andtrans-aziridines are ascribed to preferential hydrolytic opening at the aziridinium ion stage. Complete equilibration of the stereoisomeric azomethine ylides takes place prior to 1,3-dipolar additions.Thermal decomposition ofcis- andtrans-methyl 1-isopropyl-2-(m-nitrophenyl)aziridine-3-carboxylates in acetonitrile is not autocatalytic (and can be suppressed) and produces three stereoisomeric oxazolidines in identical yields and ratios, and methylN-isopropylglycine by selective hydrolytic attack at the 2-aziridine position. This result is ascribed to equilibration of the stereoisomeric aziridines prior to hydrolytic cleavage by adventitious moisture only.

ISSN:0008-4042    

DOI:10.1139/v72-359

出版商:NRC Research Press    

年代:1972

数据来源: NRC