1743-56-2Relevant academic research and scientific papers
Substituent Effects on the n and ? Molecular Orbitals of Methanimines. Photoelectron Spectra and Electronic Structures of Some Aliphatic Non-conjugated Diimines with Implications for Their Photochemistry
Bittner, Andreas J.,Rademacher, Paul
, p. 555 - 580 (2007/10/02)
The electronic structures of methanimine (1) and all possible methyl-, trifluoromethyl-, methoxy-, fluoro-, and chloro-substituted methanimines (2) - (26) have been studied by semiempirical quantum chemical calculations with special consideration of the energies of the two highest occupied molecular orbitals.By the same methods, the non-conjugated dimines (27a) - (30c) with one to four methylene groups separating the imino functions and different numbers of methyl groups have been investigated.The linear dialdimines (31) - (33) and diketimines (34) - (36)of 1,2 diaminoethane, 1,3 diaminopropane, and 1,4 diaminobutane have been prepared and characterized.The electronic structures of these compounds have been studied by photoelectron spectroscopy and semiempirical quantum chemical calculations.Acording to these results, photochemical -cycloadditions of alkyl-substituted imines are unlikely to occur.Photolysis of the diimines (31), (32), (34), and (35) only in the presence of a Lewis acid afforded products of Norrish type I reactions.
Comparison of the Tautomerization and Hydrolysis of Some Secondary and Tertiary Enamines
Capon, Brian,Wu, Zhen-Ping
, p. 2317 - 2324 (2007/10/02)
N-Phenylcyclohex-1-en-1-amine, N-(p-chlorophenyl)cyclohex-1-en-1-amine, the N-aryl-2-methylprop-1-en-1-amines, Me2C=CHNLC6H4X, L = H, D, X = H, p-Cl, p-Me, p-MeO, m-NO2, the N-alkyl-2-methylprop-1-en-1-amines, Me2C = CHNDR, R = Me, Et and the (E)-N-alkylprop-1-en-1-amines, MeHC = CHNDR, R = Me, t-Bu, were generated in solution from their N-trimethylsilyl derivatives and characterized by NMR spectroscopy.N-(p-Nitrophenyl)-2-methylprop-1-en-1-amine was isolated from the reaction of isobutyraldehyde and p-nitroaniline, and appreciable amounts (>10percent) of the N-arylcyclohex-1-en-1-amines and N-aryl-2-methylcyclohex-1-en-1-amines were found to be present at equilibrium in DMSO-d6 solution when the aryl group was phenyl, p-chlorophenyl, m-nitrophenyl, or p-nitrophenyl.The kinetics of hydrolysis of all the N-aryl secondary enamines obtained in the above ways were measured in aqueous solution and compared with those of the corresponding N-methyl tertiary enamines.With all enamines there was a region of pH in which kobsd was proportional to 10-pH, and under such conditions it was considered that the rate-determining step was C-protonation.This was supported by the isotope effect kH(1+)/kD(1+) = ca. 3, the observation of general acid catalysis, the much faster rate of hydrolysis of the corresponding imines, and the negative ρ- values.It was found that in the cyclohexenyl series the secondary and tertiary enamines were hydrolyzed at similar rates when the substituents in the aryl group were the same, but in the 2-methylcyclohexenyl and 2-methylpropenyl series the secondary enamines were hydrolyzed much faster than the corresponding tertiary enamines.This was attributed to the tertiary enamines being hindered from attaining the most favorable conformation for p-? conjugation.
