Nuclear Magnetic Resonance Spectra. Nitrogen Inversion Rates of N-Substituted Aziridines (Ethylenimines)¹

Abstract

b) T o about 200 ml. of concentrated sulfuric acid was added 22 g. (0.1 mole) of freshly prepared potassium 3-benzoyldithiocarbazate.The temperature rose rapidly to about 50". After standing a t room temperature for 4 hours the mixture was added t o 1 1. of ice-water, and the solid that separated was collected and washed with cold water. The crude product weighed 10 g. and was recrystallized from acetic acid or ethyl alcohol to give 6 g. (31y0 yield) of, bis-(2-phenyl-1,3,4-thiadiazole-5) disulfide (V), m.p. 163 ; A, , , 286 mp, log E 4.40; mol. wt., 406 (cryoscopic).Anal. Calcd. for Cl8Hlo?*T4S4: C, 49.71; H , 2.61; N, 14.50. Found: C,49.53; H,2.53; S, 14.44. Compound V also was prepared from a sample of 2-phenyl-A'2-1,3,4-thiadiazoline-5-thione (111) and concentrated sulfuric acid heated a t 50' for two minutes. A sample of I11 was dissolved in 1 i V sodium hydroxide solution and was treated with iodoform reagent. The solid that separated was identified as compound V.(c) Air was bubbled for 1 hour into a mixture of 10 g. of potassium 3-benzoyldithiocarbazate and 100 ml. of concentrated sulfuric acid warmed at 40". The mixture was poured into icc-Lt-ater atid the resulting solid was collected antl wtshctl wit11 watcr. The solid was treated with 100 nil. of saturated sodium carbonate solution and then was filtered. The insoluble material was recrystallized from ethyl acetate-petroleum ether and 2 g. (23% yield) of V was obtained. The sodium carbonate extract was neutralized with concentrated hydrochloric acid and 0.2 g. of I11 was obtained.When the reaction was repeated using a nitrogen atniosphere in place of air the yields of the two products were the same.Basic Cleavage of Bis-(2-phenyl-1,3,4-thiadiazole-5) Disulfide (V) .--About 2 g. (0.005 mole) of bis-(2-phenyl-1,3,4.thiadiazole-5) disulfide and 20 ml. of 1 * ' V sodium hydroxide was warmed on a steam-bath for 1 hour during which time it dissolved and formed a yellow colored solution. Hydrochloric acid was added until the solution was acidic and sulfur dioxide was evolved. The solution was made basic antl was extracted with ethyl acetate. The ethyl acetate was evaporated and the residue was shown by infrared analysis t o be 2-phenyl-1,3,4-thiadiazole. The basic layer was made acidic with hydrochloric acid and the solid that separated was identified as 2-phenyl-A*-1,3,4-thiadiazoline-5-thione (111). The yields were almost quantitative.The nuclear magnetic resonance spectra of various cyclic imines ranging in ring size from three to six have been examined. The spectra of N-substituted aziridine (ethplenimine) derivatives were found to be strongly temperature dependent as would be expected if the nitrogen atoms and attached groups do not lie in a plane and inversion occurs rather slowly. I t has beeii possible t o evaluate some factors which affect the inversion rates of non-planar nitrogen atoms in cyclic imines. As mould be expected, attachment of unsaturated groups to non-planar nitrogen increases the inversion rate as the result of conjugation with the ...

The Abstraction of Hydrogen Atoms From Amines and Related Compounds

“…T h e argulnent in the previous paragraph would apply equally as well to the present study if reaction [6] were taking place even to a limited extent in the lower temperature range. As the total rate of ethane production would then be the sum of processes [3] and For personal use only.…”

“…t-Butyl ethylenimine was supplied by Dr. Albert Bottini (6). t-Butyl acetaldilnine was prepared according to the method of Hurwitz (7) from t-butylamine and acetaldehyde.…”

“…Thus the effect of process [6] on the value determined for k5/k31i2 will be minimized by low concentrations of additive, [MI, as well as high methyl radical concentrations, [CH3]. I t is significant that there is appreciable difference between the magnitude of both these variables in the two studies under comparison.…”

“…In order for kB/[CI-13] to maintain its constancy the ratio The magnitude of the error of course depends on the size of the additive term within the bracketed expression of the above formula. Determination of the absolute magnitude of the effect of [6] on ethane formation and thus on the value of E5 is perhaps possible by a detailed study of diethylamine variation a t constailt temperature in the case of the D T B P pyrolyses. In a like inanner investigation of the effect of intensity and diethylamine variation a t constant temperature for the photolyses of Kozak and Gesser should produce similar information.…”

Cyclic Imides. II. Silylsuccinimides

“…spectrum of N-(triethylsily1)succinimide (2) in CHCl, was recorded down to -80" with the aim of establishing temperature dependent inversion. Although the succinimido peak is somewhat broadened relative to the sharp singlet triethylsilyl peak, the effect is small, and at -80" silylsuccinimides must still be undergoing rapid inversion as has previously been found for N-substituted imines (9).…”