Group frequencies carboxylate

Table 4.10 OH and Related C—O Group Frequencies for Alcohols and Carboxylic Acids...

Characteristic group frequencies of carboxylate salts are shown in Figure 32. In carboxylate salts, the two identical C-0 partial double bonds give rise to two bands the antisymmetric CO2... 

Figure 30. Characteristic group frequencies of carboxylic acids...

Barnes et al. [19] have given values for the C=0 frequencies of a number of acids, and Lecomte [20] has discussed the relationship between the carbonyl frequency and its surrounding structure, on the basis of the examination of a limited number of materials. This latter aspect has been further studied by Gillette [21], and especially by Flett [9, 22], whilst data on individual groups of carboxylic acids have been given by a number of other workers [23—25, 96—99]. The general findings are discussed below. 

Structural keys describe the chemical composition and structural motifs of molecules represented as a Boolean array. If a certain structural feature is present in a molecule or a substructure, a particular bit is set to 1 (true), otherwise to 0 (false). A bit in this array may encode a particular functional group (such as a carboxylic acid or an amidelinkage), a structural element (e.g., a substituted cyclohexane), or at least n occurrences of a particular element (e.g., a carbon atom). Alternatively, the structural key can be defined as an array of integers where the elements of this array contain the frequency of a specific feature in the molecule. 

Infrared IR spectroscopy is quite useful in identifying carboxylic acid derivatives The, carbonyl stretching vibration is very strong and its position is sensitive to the nature of IKT the carbonyl group In general electron donation from the substituent decreases the double bond character of the bond between carbon and oxygen and decreases the stretch mg frequency Two distinct absorptions are observed for the symmetric and antisym metric stretching vibrations of the anhydride function... 

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