Ab initio and DFT studies on the elimination kinetics 2-substituted ethyl N,N-dimethylcarbamates [(CH3)2NCOOCH2CH2Z, Z=CH2C6H5, C6H5, C(CH3)=CH2] in the gas phase

The theoretical studies on the elimination kinetics of 2-substituted ethyl N,N-dimethylcarbamates [(CH3)(2)NCOOCH(2)CH(2)Z, Z=CH2C6H5, C6H5, C(CH3)=CH2] in the gas phase were carried out using the ab initio MP2/6-31G and DFT RMPWP91/6-31G(d,p) levels of theory. These carbamates produce N,N-dimethylcarbamic acid and the corresponding substituted olefin in a rate determining step. On the basis of these calculations, the mechanism appears to be concerted, asynchronous, through a six-membered cyclic transition state structure. The acidity of the benzylic and allylic beta-hydrogen is believed to be responsible for faster elimination rates. (c) 2006 Elsevier B.V. All rights reserved.