Carboxyl sentence example
The carboxyl group constitutes another convenient startingpoint for the orientation of many types of organic compounds.
It is necessary clearly to distinguish such compounds as the amino- (or amido-) acids and acid-amides; in the first case the amino group is substituted in the hydrocarbon residue, in the second it is substituted in the carboxyl group.
Hence the positions occupied by the nitro groups in the two different nitrobrombenzoic acids must be symmetrical with respect to the carboxyl group. In 1879, Hubner (Ann., 1 95, p. 4) proved the equivalence of the second pair, viz.
P. Griess (Ber., 1872, 5, p. 192; 18 74, 7, p. 1223) orientated the three diaminobenzenes or phenylene diamines by considering their preparation by the elimination of the carboxyl group in the six diaminobenzoic acids.
The average value for the carboxyl group is 119.75 calories, i.e.Advertisement
This theory explains the fluorescence of anthranilic acid (o-aminobenzoic acid), by regarding the aniline residue as the luminophore, and the carboxyl group as the fluorogen, since, apparently, the introduction of the latter into the non-fluorescent aniline molecule involves the production of a fluorescent substance.
Piperic acid differs from piperonylic acid by the group C4H 4, and it was apparent that these carbon atoms must be attached to the carbon atom which appears in the carboxyl group of piperonylic acid, for if they were directly attached to the benzene ring polycarboxylic acids would result in oxidation.
The basicity of an organic acid, as above defined, is determined by the number of carboxyl groups present.
The simplest syntheses are undoubtedly those in which a carboxyl group is obtained directly from the oxides of carbon, carbon dioxide and carbon monoxide.
In the preceding instances the carboxyl group has been synthesized or introduced into a molecule; we have now to consider syntheses from substances already containing carboxyl groups.Advertisement
Meyer (Ber., 18 94, 2 7, p. 510 et seq.) showed that in benzenoid compounds ortho-substituents exert a great hindering effect on the esterification of alcohols by acids in the presence of hydrochloric acid, this hindering being particularly marked when two substituents are present in the ortho positions to the carboxyl group. In such a case the ester is best prepared by the action of an alkyl halide on the silver salt of the acid, and when once prepared, can only be hydrolysed with great difficulty.
With a methyl group, the chief product is an ortho-semidine, whilst with a carboxyl group, the diphenyl derivative is the chief product.
Such hydrogen bonding induces a more negative charge on the carboxyl oxygen atoms leading to an increase in the carboxyl oxygen atoms leading to an increase in the carboxylate pK a.
The terminal carboxyl of each ubiquitin is linked to the e -amino group of a lysine residue of the adjacent ubiquitin in the chain.
Amino acid-An organic compound composed of both an amino group and an acidic carboxyl group.Advertisement