D. MONOGRAPHS
Cinnamic Acid
C9H8O2
Mol. Wt. 148.16
3-phenyl-2-propenoic acid
〔621-82-9〕
Content Cinnamic Acid, when dried, contains not less than 99.0% of cinnamic
acid (C9H8O2).
Description
Cinnamic Acid occurs as a white crystalline powder having a
characteristic odor.
Identification
(1)
To 0.5 g of Cinnamic Acid, add 1 ml of sulfuric acid, and
dissolve while heating in a water bath. The color of the solution changes to a
yellow-green color. Continue heating. The color changes to a dark red color.
(2)
Dissolve 0.1 g of Cinnamic Acid in 2 ml of potassium hydroxide solution (1
→ 15), add 5 ml of potassium permanganate solution (1 → 300), and warm in hot
water. An odor of benzaldehyde is evolved.
Purity
(1)
Melting point
132−135℃.
(2) Clarity of solution
Clear
(1.0 g, ethanol 7 ml).
Clear
(0.20 g, anhydrous sodium carbonate solution (1 → 8) 2 ml and water 8
ml).
(3)
Heavy metals
Not more than 10 µg/g as Pb.
Test Solution Weigh 2.0 g of Cinnamic Acid, add 2 ml of diluted acetic acid (1 →
20) and ethanol to make 50 ml.
Control Solution To 2.0 ml of Lead Standard Solution, add 2 ml of diluted acetic
acid (1→20) and ethanol to make 50 ml.
(4)
Arsenic
(5)
Not more than 4 µg/g as As2O3 (0.50 g, Method 4, Apparatus B).
Halogenated compounds
Proceed as directed under Halogenated
Compounds in the Flavoring Substances Tests.
Loss on Drying
Not more than 1.0% (4 hours).
Residue on Ignition
Assay
Not more than 0.05% (2 g).
Weigh accurately about 0.2 g of Cinnamic Acid, previously dried, dissolve
in 10 ml of neutralized ethanol and 10 ml of water, and titrate with 0.1 mol/l sodium
hydroxide (indicator: 3 drops of phenolphthalein TS).
1 ml of 0.1 mol/l sodium hydroxide = 14.816 mg of C9H8O2