Edition: BP 2025 (Ph. Eur. 11.6 update)<\/p>\n
Preparation<\/strong><\/p>\n Menthol and Benzoin Inhalation<\/p>\n Mixture of equal parts of (1RS,2SR,5RS)-5-methyl-2-(1-methylethyl)cyclohexanol.<\/p>\n Free-flowing or agglomerated, crystalline powder or prismatic or acicular, colourless, shiny crystals.<\/p>\n Practically insoluble in water, very soluble in ethanol (96 per cent) and in light petroleum, freely soluble in fatty oils and in liquid paraffin, very slightly soluble in glycerol.<\/p>\n About 34 \u00b0C.<\/p>\n First identification: A, C. <\/em><\/p>\n Second identification: B, D.<\/em><\/p>\n A. Optical rotation (see Tests).<\/p>\n B. Thin-layer chromatography (2.2.27).<\/p>\n Test solution\u00a0 Dissolve 25 mg of the substance to be examined in methanol R and dilute to 5 mL with the same solvent.<\/p>\n Reference solution\u00a0 Dissolve 25 mg of menthol CRS in methanol R and dilute to 5 mL with the same solvent.<\/p>\n Plate\u00a0 TLC silica gel G plate R.<\/p>\n Mobile phase ethyl acetate R, toluene R (5:95 V\/V). Application 2 \u00b5L.<\/p>\n Development\u00a0 Over a path of 15 cm.<\/p>\n Drying\u00a0 In air, until the solvents have evaporated.<\/p>\n Detection\u00a0 Spray with anisaldehyde solution R and heat at 100-105 \u00b0C for 5-10 min.<\/p>\n Results The principal spot in the chromatogram obtained with the test solution is similar in position, colour and size to the principal spot in the chromatogram obtained with the reference solution.<\/p>\n C. Examine the chromatograms obtained in the test for related substances.<\/p>\n Results The principal peak in the chromatogram obtained with test solution (b) is similar in position and approximate dimensions to the principal peak in the chromatogram obtained with reference solution (c).<\/p>\n D. Dissolve 0.20 g in 0.5 mL of anhydrous pyridine R. Add 3 mL of a 150 g\/L solution of dinitrobenzoyl chloride R in anhydrous pyridine R. Heat on a water-bath for 10 min. Add 7.0 mL of water R in small quantities with stirring and allow to stand in iced water for 30 min. A precipitate is formed. Allow to stand and decant the supernatant. Wash the precipitate with 2 quantities, each of 5 mL, of iced water R, recrystallise from 10 mL of acetone R, wash with iced acetone R and dry at 75 \u00b0C at a pressure not exceeding 2.7 kPa for 30 min. The crystals melt (2.2.14) at 130 \u00b0C to 131 \u00b0C.<\/p>\n Dissolve 2.50 g in 10 mL of ethanol (96 per cent) R and dilute to 25.0 mL with the same solvent.<\/p>\n Solution S is clear (2.2.1) and colourless (2.2.2, Method II).<\/p>\n Dissolve 1.0 g in ethanol (96 per cent) R and dilute to 10 mL with the same solvent. Add 0.1 mL of phenolphthalein solution R. The solution is colourless. Not more than 0.5 mL of 0.01 M sodium hydroxide is required to change the colour of the indicator to pink.<\/p>\n Optical rotation (2.2.7)<\/strong><\/p>\n -0.2\u00b0 to + 0.2\u00b0, determined on solution S.<\/p>\n Gas chromatography (2.2.28).<\/p>\n Test solution (a) Dissolve 0.20 g of the substance to be examined in methylene chloride R and dilute to 50.0 mL with the same solvent.<\/p>\n Test solution (b)\u00a0 Dilute 1.0 mL of test solution (a) to 10.0 mL with methylene chloride R.<\/p>\n Reference solution (a) Dissolve 40.0 mg of the substance to be examined and 40.0 mg of isomenthol R in methylene chloride R and dilute to 100.0 mL with the same solvent.<\/p>\n Reference solution (b)\u00a0 Dilute 0.10 mL of test solution (a) to 100.0 mL with methylene chloride R.<\/p>\n Reference solution (c) Dissolve 40.0 mg of menthol CRS in methylene chloride R and dilute to 100.0 mL with the same solvent.<\/p>\n Column:<\/p>\n \u2014 material: glass;<\/p>\n \u2014 size: l = 2.0 m, \u00d8 = 2 mm;<\/p>\n \u2014 stationary phase: diatomaceous earth for gas chromatography R impregnated with 15 per cent m\/m of macrogol 1500 R.<\/p>\n Carrier gas nitrogen for chromatography R. Flow rate 30 mL\/min.<\/p>\n Temperature:<\/p>\n \u2014 column: 120 \u00b0C;<\/p>\n \u2014 injection port: 150 \u00b0C;<\/p>\n \u2014 detector: 200 \u00b0C. Detection Flame ionisation. Injection 1 \u00b5L.<\/p>\n Run time\u00a0 Twice the retention time of menthol.<\/p>\n System suitability:<\/p>\n \u2014 resolution: minimum 1.4 between the peaks due to menthol and isomenthol in the chromatogram obtained with reference solution (a);<\/p>\n \u2014 signal-to-noise ratio: minimum 5 for the principal peak in the chromatogram obtained with reference solution (b).<\/p>\n Limits\u00a0 Test solution (a):<\/p>\n \u2014 total: not more than 1 per cent of the area of the principal peak;<\/p>\n \u2014 disregard limit: 0.05 per cent of the area of the principal peak.<\/p>\n Maximum 0.05 per cent.<\/p>\n Evaporate 2.00 g on a water-bath and heat in an oven at 100-105 \u00b0C for 1 h. The residue weighs not more than 1.0 mg.<\/p>\n","protected":false},"excerpt":{"rendered":" Edition: BP 2025 (Ph. Eur. 11.6 update) Preparation Menthol and Benzoin Inhalation DEFINITION Mixture of equal parts of (1RS,2SR,5RS)-5-methyl-2-(1-methylethyl)cyclohexanol. CHARACTERS Appearance Free-flowing or agglomerated, crystalline powder or prismatic or acicular, colourless, shiny crystals. Solubility Practically insoluble in water, very soluble in ethanol (96 per cent) and in light petroleum, freely soluble in fatty oils and…<\/p>\n","protected":false},"author":5,"featured_media":28828,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[174],"tags":[],"class_list":["post-28827","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-medicinal-substances"],"acf":[],"_links":{"self":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/28827","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/comments?post=28827"}],"version-history":[{"count":2,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/28827\/revisions"}],"predecessor-version":[{"id":28831,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/posts\/28827\/revisions\/28831"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media\/28828"}],"wp:attachment":[{"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/media?parent=28827"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/categories?post=28827"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nhathuocngocanh.com\/bp\/wp-json\/wp\/v2\/tags?post=28827"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}DEFINITION<\/h2>\n
CHARACTERS<\/h2>\n
Appearance<\/h3>\n
Solubility<\/h3>\n
mp<\/h3>\n
IDENTIFICATION<\/h2>\n
TESTS<\/h2>\n
Solution S<\/h3>\n
Appearance of solution<\/h3>\n
Acidity or alkalinity<\/h3>\n
Related substances<\/h3>\n
Residue on evaporation<\/h3>\n