Allyl Isothiocyanate
(al' il eye'' soe thye'' oh sye' a nate).
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C4H5NS 99.16

Isothiocyanic acid allyl ester [57-06-7].
» Allyl Isothiocyanate contains not less than 93.0 percent and not more than 105.0 percent of C4H5NS.
[Caution—Allyl Isothiocyanate is a potent lachcrymator, with a pungent irritating odor. Care should be taken to protect the eyes, to prevent inhalation of fumes, and to avoid tasting. ]
Packaging and storage— Preserve in tight containers.
Identification, Infrared Absorption 197F The spectrum exhibits pronounced peaks at about 700–cm, 950–cm, 980–cm, 1300–cm, 1340–cm, 1350–cm, 1410–cm, 1420–cm, 1650–cm, 2100–cm, and 2200–cm.
Specific gravity 841: between 1.013 and 1.020.
Refractive index 831: between 1.527 and 1.531, determined at 20.
Distilling range, Method I 721: between 148 and 154.
Limit of phenols— Dilute 1 mL of it with 5 mL of alcohol, and add 1 drop of ferric chloride TS: a blue color is not produced immediately.
Assay— Transfer about 4 mL of Allyl Isothiocyanate, accurately weighed, to a 100-mL volumetric flask, add alcohol to volume, and mix. Transfer 5.0 mL of this stock solution to a 100-mL conical flask, add 50.0 mL of 0.1 N silver nitrate VS and 5 mL of ammonia TS. Connect the flask to a reflux condenser, heat on a water bath for 1 hour, and allow to cool to room temperature. Disconnect the flask from the condenser, transfer the contents of the conical flask to a 100-mL volumetric flask with the aid of water, dilute with water to volume, and mix. Pass through a dry filter, discarding the first 10 mL of the filtrate. 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 stock solution, and make any necessary correction. Each mL of 0.1 N silver nitrate is equivalent to 4.958 mg of C4H5NS.
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Topic/Question Contact Expert Committee
Monograph Elena Gonikberg, Ph.D.
Principal Scientific Liaison
(SM32010) Monographs - Small Molecules 3
USP35–NF30 Page 2101
Pharmacopeial Forum: Volume No. 27(3) Page 2509