Ph Eur
C22H38O4Zn -- 431.9 -- 557-08-4
DEFINITION
Zinc di(undec-10-enoate).
Content: 98.0 per cent to 102.0 per cent (dried substance).
CHARACTERS
Appearance: White or almost white, fine powder.
Solubility: Practically insoluble in water and in ethanol (96 per cent).
mp: 116C to 121C, it may leave a slight solid residue.
IDENTIFICATION
A. To 2.5 g add 10 ml of water and 10 ml of dilute sulphuric acid. Shake with 2 quantities, each of 10 ml, of ether. Reserve the aqueous layer for identification test C. Wash the combined ether layers with water and evaporate to dryness. To the residue add 2 ml of freshly distilled aniline and boil under a reflux condenser for 10 min. Allow to cool and add 30 ml of ether. Shake with 3 quantities, each of 20 ml, of dilute hydrochloric acid and then with 20 ml of water. Evaporate the organic layer to dryness on a water-bath.
The residue, after recrystallisation twice from ethanol (70 per cent V/V) R and drying in vacuo for 3 h, melts at 66C to 68C.
B. Dissolve 0.1 g in a mixture of 2 ml of dilute sulphuric acid and 5 ml of glacial acetic acid. Add drop-wise 0.25 ml of potassium permanganate solution. The colour of the potassium permanganate solution is discharged.
C. A mixture of 1 ml of the aqueous layer obtained in identification test A and 4 ml of water gives the reaction of zinc.
TESTS
Alkalinity: Mix 1.0 g with 5 ml of ethanol (96 per cent) and 0.5 ml of phenol red solution. Add 50 ml of carbon dioxide-free water and examine immediately. No reddish colour appears.
Alkali and alkaline-earth metals: Maximum 2.0 per cent.
To 1.0 g add 25 ml of water and 5 ml of hydrochloric acid and heat to boiling. Filter whilst hot. Wash the filter and the residue with 25 ml of hot water. Combine the filtrate and washings and add concentrated ammonia until alkaline. Add 7.5 ml of thioacetamide solution and heat on a water-bath for 30 min. Filter and wash the precipitate with 2 quantities, each of 10 ml, of water. Combine the filtrate and washings, evaporate to dryness on a water-bath and ignite. The residue weighs a maximum of 20 mg.
Sulphates: Maximum 500 ppm.
Loss on drying: Maximum 1.5 per cent, determined on 0.500 g by drying in an oven at 105C.
Degree of un-saturation: Dissolve 0.100 g in a mixture of 5 ml of dilute hydrochloric acid R and 30 ml of glacial acetic acid. Using 0.05 ml indigo carmine solution, added towards the end of the titration as indicator. Titrate with 0.0167 M bromide-bromate until the colour changes from blue to yellow.
9.1 ml to 9.4 ml of 0.0167 M bromide-bromate is required. Carry out a blank titration.
Zinc Undecylenate USP Grade
C22H38O4Zn 431.92
10-Undecenoic acid, zinc(2+) salt.
Zinc 10-undecenoate [557-08-4].
Zinc Undecylenate contains not less than 98.0 percent and not more than 102.0 percent of C22H38O4Zn, calculated on the dried basis.
Identification:
A: Acidify about 5 g with 25 mL of 2 N sulfuric acid, add 20 mL of water, and extract in a separator with two 25-mL portions of ether. Evaporate the ether solution until the odor of ether no longer is perceptible. Add potassium permanganate drop-wise to a 1-mL portion of this residue: the permanganate color is discharged.
B: A 3-mL portion of the residue of undecylenic acid obtained in Identification test A responds to Identification test B under Undecylenic Acid.
C: Dissolve about 100 mg in a mixture of 10 mL of water and 1 mL of ammonium hydroxide, and add a few drops of sodium sulfide: a white, flocculent precipitate of zinc sulfide is formed.
Loss on drying: Dry it at 105 for 2 hours: it loses not more than 1.25% of its weight.
Alkalies and alkaline earths: Boil 1.50 g with a mixture of 50 mL of water and 10 mL of hydrochloric acid, filter while hot, and wash the separated acid with about 50 mL of hot water. Render the combined filtrate and washings alkaline with 6 N ammonium hydroxide, add ammonium sulfide to precipitate the zinc completely, dilute with water to 200 mL, mix, and filter. To 100 mL of the clear filtrate add 0.5 mL of sulfuric acid, evaporate to dryness, and ignite over a low flame to constant weight: the weight of the residue does not exceed 7.5 mg (1.0%).
