Carboxylic acids terms Links

Amides are the derivatives of the carboxylic acids. In amides the carboxylic acid is linked with ammonia or an amine. Like esters, the parent carboxylic acid is identified. This is then termed an alkanamide and includes the nitrogen atom. For example, linking ethanoic acid with ammonia gives ethanamide ... 

Amino acids become linked by reactions that occur between the amine group of one amino acid and the carboxyl group of another. As shown in Figure 22.23, this polymerization produces a molecule of water and, hence, is a condensation reaction. Naturally occurring polypeptides with molecular weights in excess of 10,000 daltons are termed proteins. These biomolecules are ubiquitous in marine organisms and are not specific to particular species. Proteins are important components of enzymes as well as of structural parts and connective tissues. 

The values of 3.3 to 3.6 obtained for the pK pp value to be assigned to the C-25 gel is close to the pK value of 3.31 (I = O.lCNaClO )) published for methoxyacetic acid [58], the weak carboxylic acid that most closely resembles the weak-acid functionality repeated in the cross-linked carboxymethyldextran. It can be concluded, on the basis of this observation, that Eq. (25) provides an adequate resolution of pKjn,. Indeed, the resemblance between pKjpp and pKjp, has led to the use of statistical arguments for the rationali2ation of the absence of nonideality in the a/(l - a) term. The pKjpp values for the highly swollen gel of C-50 at Cs = 0.01 mol dm, on the other hand, increases with increasing a. The extrapolated pK pp values of 3.3-3.6 at a = 0 are consistent with the values of 3.3-3.6 obtained for the C-25 gel over the a range studied. 

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