Size of alkyl group

The trends that are evident, especially from basicities of amines measured in the gas phase, point to increasing basicity with the number and size of alkyl groups on the nitrogen atom. 

A limit to the use of these steric barriers for the determination of the relative size of alkyl groups was pointed out in the study of the rotational barriers in 4-r-Buthiazoline-2-thiones 65a-c and in 66a-c (Scheme 51). 

The methyl group is the smallest polyhedral substituent which can interact with its neighbors. Its intimate behavior is of primary importance for the quantitative treatment of steric effects, since it is often taken (as a combined atom) as a reference for the size of alkyl groups (Section II). The conformational aspect of the steric size of a methyl and its ability to induce conformational changes was clearly evident in the study of various poly-methylisopropylpyridines or -pyridinium salts 81a-e (83T4209) (Scheme 63). 

The electron donating/withdrawing power of substituents at the a-carbon of the monomer also influence the magnitude of and K2. This is well illustrated by the contrasting effects of change in size of alkyl group substituents on the rate of cationic and anionic polymerization. 

Alkyl acrylate-co-methyl methacrylate Single Tg II had an alkyl group of ethyl or -butyl miscibility depended on compositions of I and II miscibility increased and then decreased with increasing size of alkyl group of II (Zhao et al. (1991)3) Chu and Paul (1999)... 

In this chapter, densities and molar excess volumes of binaiy (1,2-ethanediol + water) systems in the temperatnre range of 308.2-313.2 K at atmospheric pressure are reported. The measurements are part of a long-term stndy to examine the dependence of excess volumes on temperatnre. In the earlier papers (Dean, 1985 Douheiet et al., 1991 Geyeretal., in press Kapadi etal., 2000 Nittaetal., 1977 Redlich and Kister, 1948 Span and Wagner, in press) extensive database on the thermodynamic interactions in binary mixtures of 1,2-ethanediol with water was presented. The aim of this work is to provide a set of values for the characterization of the molecular interactions of these mixtures and to examine the effect of the size of alkyl group of the diol. 

How is the equihbrium constant for the s-trans to s-cis conversion affected by the size of alkyl groups in 2,3-dialkyl-substituted 1,3-butadienes ... 

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