Molecular formula. C28H29NO4
Relative molecular mass. 443.5
Chemical name. Benzyldimethyl(2-phenoxyethyl)ammonium 3-hydroxy-2-naphthoate (1:1); N,N-dimethyl-N-(2-phenoxyethyl)benzenemethanaminium salt with 3-hydroxy-2-naphthalenecarboxylic acid (1:1); CAS Reg. No. 3818-50-6.
Description. A yellow to greenish yellow, crystalline powder; odourless or almost odourless.
Solubility. Practically insoluble in water, ether R and benzene R; soluble in 50 parts of ethanol (~750 g/l) TS.
Storage. Bephenium hydroxynaphthoate should be kept in a tightly closed container.
Additional information. Even in the absence of light. Bephenium hydroxynaphthoate is gradually degraded on exposure to a humid atmosphere, the decomposition being faster at higher temperatures.
Definition. Bephenium hydroxynaphthoate contains not less than 99.0% and not more than 101.0%, of C28H29NO4, calculated with reference to the dried substance.
• Either test A alone or tests B and C may be applied.
A. Carry out the examination as described under 1.7 Spectrophotometry in the infrared region. The infrared absorption spectrum is concordant with the spectrum obtained from bephenium hydroxynaphthoate RS or with the reference spectrum of bephenium hydroxynaphthoate.
B. See the test described below under "Related substances". The principal spots obtained with solution B at 254 nm correspond in position, appearance, and intensity with those obtained with solution C.
C. Melting temperature, about 170°C with decomposition.
Chlorides. For the preparation of the test solution, boil 0.7 g with 30 ml of water, cool in ice and filter. Add 10 ml of nitric acid (~130 g/l) TS to the filtrate, and proceed as described under 2.2.1 Limit test for chlorides; the chloride content is not more than 0.35 mg/g.
Sulfated ash. Not more than 2.0 mg/g.
Loss on drying. Dry to constant weight at 105°C; it loses not more than 10 mg/g.
Related substances. Carry out the test described under 1.14.1 Thin-layer chromatography, using silica gel R4 as the coating substance and a mixture of 5 volumes of 1-butanol R, 4 volumes of water and 1 volume of acetic acid (~300 g/l) TS as the mobile phase. Apply separately to the plate 5 μl of each of 3 solutions in methanol R containing (A) 40 mg of the test substance per ml, (B) 0.40 mg of the test substance per ml, and (C) 0.40 mg of bephenium hydroxynaphthoate RS per ml. After removing the plate from the chromatographic chamber, allow it to dry in air, and examine the chromatogram in ultraviolet light (254 nm and 365 nm). At 254 nm two principal spots are visible with each of the solutions A, B, and C, whereas at 365 nm only the spots closer to the solvent front fluoresce. Any additional spot visible with solution A other than the two principal spots, is not more intense in appearance in both lights than the spot obtained closer to the starting line of solution B.
Afterwards, spray the plate first with sodium molybdotungstophosphate TS, then with sodium carbonate (200 g/l) TS, and examine the chromatogram in daylight. Two principal spots are obtained with each of the solutions A, B, and C. Any additional spot obtained with solution A, disregarding those that may have been visible in ultraviolet light, is not more intense than the principal spot closer to the solvent front obtained with solution B.
Assay. Dissolve about 0.4 g, accurately weighed, in 30 ml of glacial acetic acid R1, and titrate with perchloric acid (0.1 mol/l) VS as described under 2.6 Non-aqueous titration, Method A. Each ml of perchloric acid (0.1 mol/l) VS is equivalent to 44.35 mg of C28H29NO4.