Methyl salicylate
EUROPEAN PHARMACOPOEIA 5.0
ASSAY
To 1.000 g add 20.0 ml of 1 M sodium hydroxide. Heat at
about 70 °C for 1 h. Cool rapidly in an ice bath. Prepare a
blank in the same manner. Carry out the titration on the
solutions at room temperature. Titrate the excess sodium
hydroxide with 0.5 M sulphuric acid, continuing the titration
until the second point of inflexion and determining the
end-point potentiometrically (2.2.20).
1 ml of 1 M sodium hydroxide is equivalent to 152.1 mg of
C 8 H 8 O3 .
ASSAY
Dissolve 0.500 g in 25 ml of alcohol R. Add 0.05 ml of phenol
red solution R and neutralise with 0.1 M sodium hydroxide.
To the neutralised solution add 50.0 ml of 0.1 M sodium
hydroxide and heat under a reflux condenser on a water-bath
for 30 min. Cool and titrate with 0.1 M hydrochloric acid.
Calculate the volume of 0.1 M sodium hydroxide used in the
saponification. Carry out a blank titration.
1 ml of 0.1 M sodium hydroxide is equivalent to 15.21 mg
of C8H8O3.
IMPURITIES
STORAGE
Store protected from light.
01/2005:0511
METHYLATROPINE BROMIDE
A. R = H : 4-hydroxybenzoic acid,
Methylatropini bromidum
B. R = CH2-CH3 : ethyl 4-hydroxybenzoate,
C. R = CH2-CH2-CH3 : propyl 4-hydroxybenzoate,
D. R = CH2-CH2-CH2-CH3 : butyl 4-hydroxybenzoate.
01/2005:0230
METHYL SALICYLATE
Methylis salicylas
C18H26BrNO3
Mr 384.3
DEFINITION
Methylatropine bromide contains not less than 99.0 per
cent and not more than the equivalent of 101.0 per cent of
(1R,3r,5S)-3-[[(2RS)-3-hydroxy-2-phenylpropanoyl]oxy]-8,8dimethyl-8-azoniabicyclo[3.2.1]octane bromide, calculated
with reference to the dried substance.
Mr 152.1 CHARACTERS
A white, crystalline powder or colourless crystals, freely
DEFINITION
soluble in water, sparingly soluble in alcohol.
Methyl salicylate contains not less than 99.0 per cent m/m
It melts at about 219 °C, with decomposition.
and not more than the equivalent of 100.5 per cent m/m of
IDENTIFICATION
methyl 2-hydroxybenzoate.
First identification : B, E.
CHARACTERS
Second identification : A, C, D, E.
A colourless or slightly yellow liquid, very slightly soluble in
water, miscible with alcohol and with fatty and essential oils. A. It complies with the test for optical rotation (see Tests).
B. Examine by infrared absorption spectrophotometry
IDENTIFICATION
(2.2.24), comparing with the spectrum obtained with
methylatropine bromide CRS.
A. Heat 0.25 ml with 2 ml of dilute sodium hydroxide
solution R on a water-bath for 5 min. Add 3 ml of dilute C. To 5 ml of solution S (see Tests) add 2 ml of dilute sodium
sulphuric acid R. A crystalline precipitate is formed.
hydroxide solution R. No precipitate is formed.
Filter. The precipitate, washed with water R and dried at D. To about 1 mg add 0.2 ml of fuming nitric acid R and
100 °C to 105 °C, melts (2.2.14) at 156 °C to 161 °C.
evaporate to dryness on a water-bath. Dissolve the
B. To 10 ml of a saturated solution add 0.05 ml of ferric
residue in 2 ml of acetone R and add 0.1 ml of a 30 g/l
chloride solution R1. A violet colour develops.
solution of potassium hydroxide R in methanol R. A
violet colour develops.
TESTS
E. It gives reaction (a) of bromides (2.3.1).
Appearance of solution. To 2 ml add 10 ml of alcohol R.
The solution is clear (2.2.1) and not more intensely coloured TESTS
than reference solution Y7 (2.2.2, Method II).
Solution S. Dissolve 1.25 g in carbon dioxide-free water R
Acidity. Dissolve 5.0 g in a mixture of 0.2 ml of bromocresol and dilute to 25 ml with the same solvent.
green solution R and 50 ml of alcohol R previously
Appearance of solution. Solution S is clear (2.2.1) and not
neutralised to a blue colour by addition of 0.1 M sodium
more intensely coloured than reference solution B9 (2.2.2,
hydroxide. Not more than 0.4 ml of 0.1 M sodium hydroxide Method II).
is required to restore the blue colour.
Acidity or alkalinity. To 10 ml of solution S add 0.1 ml of
Refractive index (2.2.6) : 1.535 to 1.538.
phenolphthalein solution R ; the solution is colourless. Add
Relative density (2.2.5) : 1.180 to 1.186.
0.5 ml of 0.01 M sodium hydroxide ; the solution is red.
C 8 H 8 O3
2014
See the information section on general monographs (cover pages)