Potassium methyl hydroxybenzoate

Synonyms methyl 4-hydroxybenzoate potassium salt potassium methyl hydroxybenzoate. 

Boil about 01 g with 50 ml of N sodium hydroxide for thirty minutes under reflux. Cool, add 50 ml of 01N bromine and 10 ml of concentrated hydrochloric acid. Allow to stand for half an hour, shaking repeatedly during the first fifteen minutes, add 2 g of potassium iodide and titrate the liberated iodine with O IN sodium thiosulphate. 1 ml of 0 1 N bromine == 0 002536 g methyl hydroxybenzoate, CgHgOa 0 002902 g sodium salt of the methyl ester 0 003003 g propyl hydroxybenzoate, C10H12C3, and 0 003370 g sodium salt of the propyl ester. 

This with potassium hydroxide in methanol forms de-OiV-dimethylarmepavine, m.p. 86-7°, (B. HCl, m.p. 229-30°) of which the methiodide, m.p. 233-4°, on treatment with alkali decomposes into trimetHylamine and a -p-anisyl-/3-(3 4-dimethoxy- 6 - vinylphenyl) -ethylene, m.p. 79°. The latter is oxidised by permanganate in acetone to anisic and m-hemipinic acids. With ethyl sulphate and alkali, armepavine gives 0-ethylarmepavine, an oil, which permanganate oxidises to p-ethoxybenzoic acid. Armepavine is similarly oxidised to p-hydroxybenzoic acid and l-keto-6 7-dimethoxy-2-methyl-1 2 3 4-tetiahydrowoquinoline and is therefore 6 7-dimethoxy-l-p-hydroxybenzyI-2-methyI-l 2 3 4-tetrahydrowoquinoline, i.e., it is laudanosine (p. 187) with MeO. at C replaced by H and MeO at C changed to HO. ... 

Phenol readily couples with diazonium salts to yield coloured compounds. The latter can be nsed for the photometric detection of phenol as in the case of diazotized 4-nitroaniline. Sahcylic acid (2-hydroxybenzoic acid) can be prodnced by the Kolbe-Schmitt reaction (stndied by the density functional method ) from sodinm phenolate and carbon dioxide, whereas potassium phenolate gives the para compound. Alkylation and acylation of phenol can be carried out with aluminium chloride as catalyst methyl groups can also be introduced by the Mannich reaction. Diaryl ethers can only be produced under extreme conditions. 

Methyl-p-hydroxybenzoate (33.6 g, 220 mmol) and potassium carbonate (30.4 g, 220 mmol) are dissolved in DMF (180 mL). The solution is heated to 70-80°C with stirring, and dibromooctane (25 g, 90 mmol) is added to the solution, which is heated overnight. Monomer 5 is isolated by precipitation into water followed by recrystallization. The di-ester (30 g, 70 mmol) is hydrolysed with potassium hydroxide (24.3 g, 435 mmol). 

To a three-necked round-bottomed flask (1 L) equipped with a reflux condenser, thermometer, a dropping funnel (250 mL), and a magnetic stirrer bar, add dimethylformamide (300 mL) and anhydrous potassium carbonate (69.1 g, 0.5 mol). Using a powder funnel, add methyl p-hydroxybenzoate (60 g, 0.40 mol) together with the potassium iodide. Heat the solution to 90°C and add 6-chlorohexyl ethanoate (97.4 g, 0.54 mol) drop-wise over several hours. Stir the solution for a total of 24 h whereupon TLC (silica gel, 3 2 petroleum ether ethyl acetate) should indicate the complete conversion of starting material. 

Salicylic acid can be prepared by the oxidation of o-hydroxy-benzyl alcohol, by the fusion of o-toluenesulphonic acid and other ortho acids with potassium hydroxide, by heating with water the diazo compound formed from anthranilic acid. It can be obtained with a favorable yield when o-cresol is fused with potassium hydroxide and lead peroxide the latter compound oxidizes the methyl radical to carboxyl. A mixture of o- and p-hydroxybenzoic acid is obtained from phenol by the Tiemann-Reimer synthesis (507). 

Hydroxybenzoic acid, methyl ester, potassium salt. See Potassium methylparaben 4-Hydroxybenzoic acid, methyl ester, sodium salt. See Sodium methylparaben 4-Hydroxybenzoic acid, 1-methylethyl ester. 

Phenolic acids. Table 11 lists the Rf values for a number of phenolic acids and certain of their relatives on silica gel, silanized silica gel, cellulose, and polyamide layers. Silica gel (Silica Rapid Platten Woelm F-254) was used with solvents I [dichloromethane-toluene-formic acid (50 40 10)] and II [dichloromethane-acetic acid-water (100 50 50, lower phase)], followed by UV examination of the plates and subsequent spraying with 1 % methanolic ferric chloride. HPTLC precoated plates with silica gel 60 F-254, RP-8, and Wang polyamide were used with solvents 111 [benzene-ethyl acetate-formic acid (40 10 5)], IV [ethanol-water (55 45)], and IX [benzene-ethyl methyl ketone-methanol (60 26 14)], respectively. The upper part of Table 11 lists the Revalues of hydroxybenzoic acids and the lower part those for hydroxycinnamic acids. For columns V, VI, VII, and VIII, the solvents used were 2% formic acid (V), 20% potassium chloride solution (VI), isopropanol- ammonium hydroxide-water (8 1 1) (VII), and 10% acetic acid (VIII). For each layer the relative trends of the Revalues follow the polarity of the compounds listed. Table 12 gives the Revalues for certain phenolic acids on silver oxide-impregnated silica gel G by two-dimensional development on cellulose (107). 

E218 Methyl p-hydroxybenzoate E252 Potassium nitrate... 

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