Association Between Carboxylic Acids

This view is also supported by the fact that on esterifying the group, the tendency to form molecular associations is completely lost. In terms of the information on page 63 there are two reasons for this. First, by steric screening, the effect of the dipole field of the COOH group is diminished and, in the absence of a mobile H atom, any quantum mechanical 

Miiller, Proc. Roy. Soc. London (A) 164, 624 (1936) and many investigations published in the same periodical in the last 16 years. 

To what extent the non-polar lipoid components of long-chain hydrocarbon molecules screen the effect of the polar hydrophile, and outwardly attain the ascendancy through their own f rce effects, cannot be stated with certainty. It is, however, very probable that the COOH group is responsible, in the sense discussed above, for the presence of double molecules of benzoic acid in benzene whereas, for an association effect in water, it is rather a case of interaction of benzene nuclei, because in aqueous solution the COOH groups must certainly be extensively hydrated. 

Energy op Formation of Double Molecules op Simple Carboxylic Acids 

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In aqueous solution intermolecular association between carboxylic acid molecules IS replaced by hydrogen bonding to water The solubility properties of carboxylic acids are similar to those of alcohols Carboxylic acids of four carbon atoms or fewer are mis cible with water m all proportions... 

Table 6-4. Association constants for complexes between carboxylic acids and nitrogen bases in aprotic solvents and corresponding association constants and site densities for binding of the base to a molecu-larly imprinted polymer.

ASSOCIATION CONSTANTS FOR COMPLEXES BETWEEN CARBOXYLIC ACIDS AND NITROGEN BASES IN APROTIC SOLVENTS AND CORRESPONDING ASSOCIATION CONSTANTS AND SITE DENSITIES FOR BINDING OF THE BASE TO A MIP... 

Polymeric association of different molecules through multiple hydrogen bonding has been used for the formation of non-liquid-crystalline bulk solids [12], fibrous solids for gelation in solvents [119], and as monolayers [120], Simpler H-bonding such as the interaction between carboxylic acid and pyridine has also been shown to be useful for one- or two-dimensional aggregates in solid states [121-124], For example, a one-dimensional polymeric complex from an A-B type monomer is formed in crystalline solids [121],... 

Stable metabolic associations generally between pairs of anaerobic bacteria have been termed syntrophs, and these are effective in degrading a number of aliphatic carboxylic acids or benzoate under anaerobic conditions. These reactions have been discussed in reviews (Schink 1991, 1997 Lowe et al. 1993) that provide lucid accounts of the role of syntrophs in the degradation of complex organic matter. Two examples are given here to illustrate the experimental intricacy of the problems besetting the study of syntrophic metabolism under anaerobic conditions ... 

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