M-Aminobenzoic acid

Seijeant235 used values of 3.08 and 4.77 respectively for the pK 1 and pK2 values of m-aminobenzoic acid in water at 25 °C and derived a pKa value for the neutral acid of 4.20. He concluded that the value of am for NH2 is effectively 0.00. Seijeant also considered p-aminobenzoic acid and derived a value for ap of NH2 equal to —0.57. 

On the basis of studies on the metabolism of the fish anesthetic, methane sulfonate of m-aminobenzoic acid ethyl ester (MS-222), by a shark (the spiny dogfish, Squalus aeanthias), Maren et al. (25) reported the formation of a metabolite, m-aminobenzoic acid, by cleavage of the ester bond (Figure 1). This ester-hydrolyzed product was not partitioned across the gill, but was slowly excreted by the kidney. 

Finally, the zwitterion is not the major form for all amino acids. For both o-aminobenzoic acid (anthrani-lic acid) and p-aminobenzoic acid, the uncharged species is the more prevalent form whereas the zwitterion/uncharged ratio for m-aminobenzoic acid is about 2.31. This behavior arises primarily from the low pK values for the aromatic ring s amino group e.g., the pi i and pKi values for anthranUic acid are 2.05 and 4.95 and the pA"a value for the ester is only 2.09). 

Ethane (crit. temp., upper layer, 39.8) LCST, 38.1 n-Heptane Cyclohexane Decalin Tetralin Paraffin waxes Paraffinic oils Naphthenic oils Higher alcohols (Cf. Figure Fourteen Amides Five primary Amines Six secondary Amines Three tertiary Amines m-Aminobenzoic acid (m.p. 174)... 

ETHYL ALCOHOL (continued) Thirteen fatty Acids Fourteen Amides (in 95% EtOH) m-Aminobenzoic acid (m.p. 174) jd-Ami noben zoic acid (m.p. 187) Anisic acid (m.p. 134.2) Anthranilic acid (m.p. 147) Benzamide (m.p. 130)... 

Chromium tetraphenyl acid m-aminobenzoate, 2(CeH5)4Cr. 02C.C6H4.NH2.NH2.C6H4.C02H, from m-aminobenzoic acid and the pentaphenyl base, melts at 130° C. p-Aminobenzoic acid yields 3 (C6H5 )4Cr. O 2C. C6H4.NH 2.2NH 2. C6H4. CO 2H, M.pt. 141° C. 

Matheson Company m-aminobenzoic acid was used without further purification. 

As a consequence of the complications associated with the theoretical derivation of the relationship between electrophoretic mobility and the shape of the particle, attempts have been made to solve the problem experimentally. Unfortunately the results in this connection appear to be equally inconclusive. Abramson studied the movement of spherical particles of various oils and of needles of asbestos and of m-aminobenzoic acid coated with the same protein, e.g., gelatin or egg albumin, in each case the results showed that, provided the surface of the particle was completely covered with the protein, the electrophoretic mobility is independent of the shape of the moving particle. ... 

S-Carboxydiphenylamine-O -arsinic acid is prepared from m-aminobenzoic acid in a similar manner to the 2-carboxy-acid, amyl alcohol replacing nitrobenzene in the condensation mixture. It forms colourless needles, M.pt. 238° to 289° C. lO-Ckloro-5 10-dihydro-phenarsazine-S-earboaylic acid is obtained from it in a similar way to the above, and is a yellow compound, unmelted below 300° C., and very sparingly soluble in organic solvents. 

This gradation is illustrated by the results obtained with the diazonium salts from the isomeric aminobenzoic acids. When the orthQ diazonium nitrate is treated with absolute ethanol only reduction occurs ethyl benzoate is obtained in 53% yield.f The diazonium acid sulfate derived from m-aminobenzoic acid is converted into a mixture of ethyl benzoate and ethyl m-ethoxybenzoate, the former preponderating. - Finally, with the p-diazonium salts the ether reaction is the favored one - from the nitrate the yields of p-ethoxybenzoic acid and ethyl benzoate are 60% and 12%, respectively. 

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