The effects of structural changes in NN-dialkylcarbamoyl chlorides and in some hydroxylic compounds as solvolytic agents, of solvent polarity, and of the kinetic mass-law, on the rates of solvolyses have been studied. The pseudounimolecular constants are enhanced by the increase of the electron-releasing effects of N-alkyl groups as well as by increasing solvent polarity, and are sensitive to the presence of chloride ions. These results are in agreement with the assumption of the unimolecular mechanism in all cases. The isokinetic relationships suggest two interaction mechanisms by solvation of the transition states.' Traian Vuia ', Timisoara, P.O.B. 103, Romania CARBONIC ACID CHLORIDES, as a particular kind of acyl chlorides, show interesting features in nucleophilic substitution mechanisms, e.g. the reactions of ethyl chloroformate with substituted anilines and hydrolyses of substituted aryl chloroformates.2 Although the solvolysis of alkyl chloroformates has been widely investigated, only a few studies of the reactions of NNdialkylcarbamoyl chlorides have been reported. Hall 394 has demonstrated the unimolecular mechanism of hydrolysis of NN-dimethylcarbamoyl chloride in waterdioxan (86.1% v/v) on the basis of the kinetic mass-law effect of the chloride ion, the insensivity of the reaction rate to strong nucleophiles (such as the hydroxide ion, pyrrolidine, or hydroxylamine), the activation parameters, and the catalytic action of Hg++ ions. This mechanism has been confirmed for the hydrolysis of NN-di-isopropylcarbamoyl and NN-pentamethylenecarbamoyl chlorides in water-acetone (10.9% v/v) and for NN-dimethylcarbamoyl chloride in water.6Hall has suggested a bimolecular mechanism for the reactions of NN-dimethylcarbamoyl chloride with aliphatic amines.' RESULTS Kinetics were followed by direct conductonietric measurements. The pseudo-first-order rate constants for the c O t -2 -'I
the CND0/2 and nb-initio calculationsra1, which show the reliability of the approximation chosen.In the 'H-NMR spectrum of the cation [C,H,]' Olah eta/.r3J found at room temperature one single signal which was split at lower temperatures. These authors -100' Table. Localized three-center molecular orbitals. \ I I Linear combination coefficients Atom i Function i [C,H,]+ ~ B,H, 1 B,H,, ab lriitio [8] [a] C', B' 0.1995 0.0404 H 0.0404 0 0 0.4208 0.3632 ' 0.2143 Localized proportion (%) 96.1 [a] The linear combination coefficients of C N D O calculations refer to orthogonalized (Lowdin) atomic orbitals and thus their absolute values in bonding molecular orbitals aregreater than thecorresponding coefficients in ab-initio calculations which refer to ordinary nonorthogonal atomic orbitals. assigned the structure of a o-complex to the solvated cation. According to our calculations the %-complex should be more stable in the gas phase. This need not contradict our results since 7t-and o-complexes can differ considerably in their solvation energies and in their interaction with the counter-ion. Recently Helgstrand[" reported CND0/2 calculations on the o-complex of [C,H,]'. This author's results agree well with ours, especially as regards bond angles and CH distances.We have been able to prepare the levorotatory form of 3-methyl-l-(p-diethylaminophenyl)-2-phospholene I-oxide ( I ) via its salt with (+)-9-camphorsulfonic acid. To thebest of our knowledge this is the first resolution of a chiralic phosphacyclic compound ['].Methylene chloride solutions of ( I ) [ * , 31 (16.5 mmol in 10ml) and (t )-9-carnphorsuIfonic acid (previously dried in vacuum over P,O, ; 16.2mmol in 160ml) were thoroughly mixed and the solvent subsequently removed in vacuum. The residual syrup was dissolved in 75 ml boiling benzene and the hot solution rendered slightly turbid by addition of 3-4ml n-heptane. By very slow and careful cooling, approximately 4.1 g of the camphorsulfonate of ( I ) could be obtained. After double recrystallization from benzene with a little n-heptane the specific rotation and melting point were constant ([a];'= -40.3' (benzene); m.p. 103-104°C). The difference between the UV spectrum (in cyclohexane) of compound ( I ) (A,,, = 277 nm ; log E = 4.45) and that of the salt (I.,,, = 281 nm ;log E = 3.03) shows that an ammonium (and no phosphonium) salt is present.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.