Detail of "16782-08-4"

Reference

Regioselective carboxylation of phenols with carbon dioxide

Rahim, Mohammad Abdur; Matsui, Yoshihisa; Matsuyama, Takanori; Kosugi, Yoshio (Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue 690-8504, Japan). Bulletin of the Chemical Society of Japan, 76(11), 2191-2195 (English) 2003 Chemical Society of Japan. CODEN: BCSJA8. ISSN: 0009-2673. DOCUMENT TYPE: Journal CA Section: 25 (Benzene, Its Derivatives, and Condensed Benzenoid Compounds) A few novel methods were developed for the regioselective prepn. of p-hydroxybenzoic acid (pHBA) and its amino deriv. by means of the Kolbe-Schmitt reaction. Thus, the carboxylation of tetraalkylammonium phenoxide at 125 °C under the CO2 pressure of 5.0 MPa in the presence of K2CO3 gave pHBA in a max. yield of 56% with the regioselectivity of 97-100%. The carboxylation of potassium phenoxide (PhOK) at 230 °C under the CO2 pressure of 0.5 MPa also gave pHBA regioselectively in a 39% yield, together with unaltered phenol (61%). Under such conditions, the potassium salt of salicylic acid (SA) once formed was transformed into pHBA. Heat treatment of the dipotassium salt of 13C labeled SA indicated that the transformation occurs via two pathways, i.e., the intramol. rearrangement of the salicylate (66%) and the decarboxylation of the salicylate followed by the recarboxylation of the resulting PhOK (34%). Furthermore, the carboxylation of cesium m-aminophenoxide and 5-amino-1-naphthoxide with CO2 gave regioselectively 4-hydroxyanthranilic and 8-amino-4-hydroxy-1-naphthoic acids, resp., in good yields. This is a simple one-pot reaction giving these industrially useful acids with good yields.Except for chemicals metioned above, 16782-08-4 and 38171-38-9 are also used. .

Method for separation of p-hydroxybenzoic acid

Suzuki, Toshinobu; Saima, Hitoshi; Ijiri, Makiko; Sato, Nobuyuki; Matsura, Akinori (Kawasaki Steel Corp., Japan). Jpn. Kokai Tokkyo Koho JP 04226938 A2 17 Aug 1992 Heisei, 7 pp. (Japan). CODEN: JKXXAF. CLASS: ICM: C07C065-03. ICS: C07C051-43. APPLICATION: JP 91-143071 14 Jun 1991. PRIORITY: JP 90-156334 14 Jun 1990. DOCUMENT TYPE: Patent CA Section: 25 (Benzene, Its Derivatives, and Condensed Benzenoid Compounds) p-Hydroxybenzoic acid (I) is sepd. from a Kolbe-Schmitt reaction mixt. by (a) washing the reaction mixt., obtained by reaction of a phenol alkali and/or a substituted phenol alkali with CO2, with a liq. C￡15 hydrocarbon and/or C￡10 O-contg. compd. other than carboxylic acids followed by sepn., (b) dissolving the washed residue in H2O and acidifying the resultant aq. soln. with a mineral acid, (c) heating the acidic soln. to dissolve I and removing (un)substituted PhOH and/or org. impurities, (d) sepg. residual insol. impurities from the heated acidic soln. under heating, (f) cooling the heated acidic soln. to deposit I, and (g) sepg. and collecting I from the acidic soln. The process does not use an emulsion-forming liq-liq. sepn. procedure and effectively separates I from a reaction medium, byproducts, and colored impurities by using single acidification step, and is effectively used even for a reaction mixt. contg. large amts. of impurities such as the one obtained from tar acid. Thus, a tar acid was treated with KOH and dried to give a tar acid potassium salt mixt. contg. PhOK, cresol potassium salt, xylenol potassium salt, and 6.4 wt.% unknown which (36. 16782-08-4 is also in the experiment.6 g) was heated with CO2 in a high b.p. fraction of gas oil at 3.2 kg/cm2 gage and 290° to give a dark brown reaction mixt. Acetone (80 g) was added to 30 g of the latter mixt. contg. 4.17 g I and 0.01 salicylic acid (II) as acids and filtered under stirring to give a solid mainly contg. I K salt which was dissolved in 100 mL H2O, adjusted to pH 2 with H2SO4, heated to boil to dissolve I and also distill residual PhOH, cresol, the org. solvent, a part of II, and then filtered to remove insol. impurities. The filtrate was passed through 0.2 g activated charcoal and then cooled to 5° to give after filtration and washing with H2O 3.62 g I of 99.5% purity. .