Allyl Isothiocyanate
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This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition
Issued and maintained by the United States Pharmacopeial Convention (USP)
C4H5NS 99.15
3-Isothiocyanato-1-propene;
Isothiocyanic acid allyl ester CAS RN®: 57-06-7; UNII: BN34FX42G3.
1 DEFINITION
Allyl Isothiocyanate contains NLT 93.0% and NMT 105.0% of allyl isothiocyanate (C4H5NS).
[Caution—Allyl Isothiocyanate is a potent lachrymator, with a pungent, irritating odor. Care should be taken to protect the eyes, to prevent inhalation of fumes, and to avoid tasting.]
2 IDENTIFICATION
Change to read:
A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197F (CN 1-May-2020) : The spectrum exhibits pronounced peaks at about 700, 950, 980, 1300, 1340, 1350, 1410, 1420, 1650, 2100, and 2200 cm−1.
3 ASSAY
Procedure
Sample solution: Transfer 4 mL into a 100-mL volumetric flask, and dilute with alcohol to volume.
Analysis: Transfer 5.0 mL of the Sample solution to a 100-mL conical ask, and add 50.0 mL of 0.1 N silver nitrate VS and 5 mL of ammonia TS. Connect the ask to a reux condenser, heat on a water bath for 1 h, and allow to cool to room temperature. Disconnect the flask from the condenser, transfer the contents of the conical ask to a 100-mL volumetric ask with the aid of water, and dilute with water to volume. Pass through a dry filter, discarding the first 10 mL of the ltrate. To 50.0 mL of the subsequent filtrate add 5 mL of nitric acid and 2 mL of ferric ammonium sulfate TS, and titrate the excess silver nitrate with 0.1 N ammonium thiocyanate VS. Perform a blank determination, using 5 mL of alcohol in place of the Sample solution, and make any necessary correction. Each mL of 0.1 N silver nitrate is equivalent to 4.958 mg of allyl isothiocyanate (C4H5NS).
Acceptance criteria: 93.0%–105.0%
4 IMPURITIES
Limit of Phenols
Sample solution: Dilute a 1-mL sample with 5 mL of alcohol.
Analysis: Add 1 drop of ferric chloride TS to the Sample solution.
Acceptance criteria: A blue color is not produced immediately.
5 SPECIFIC TESTS
Specific Gravity 〈841〉: 1.013–1.020
Refractive Index 〈831〉: 1.527–1.531, determined at 20°
Distilling Range, Method I〈721〉: 148°–154°
6 ADDITIONAL REQUIREMENTS
Packaging and Storage: Preserve in tight containers.
