Valeric Acid,
C5H10O2—102.13 [109-52-4]—Clear, colorless liquid.
C5H10O2—102.13 [109-52-4]—Clear, colorless liquid.
Assay—
Accurately weigh about 500 mg, transfer to a suitable container, add 30 mL of water, and mix. Add 40 mL of water, and mix. Add phenolphthalein TS, and titrate with 0.1 N sodium hydroxide VS. Each mL of 0.1 N sodium hydroxide is equivalent to 10.21 mg of C5H10O2: not less than 99.0% of C5H10O2 is found.
Valerophenone,
C11H14O—162.23 [1009-14-9]—Colorless liquid.
C11H14O—162.23 [1009-14-9]—Colorless liquid.
Assay—
Inject an appropriate specimen into a suitable gas chromatograph (see Chromatography 
621
) equipped with a flame-ionization detector, helium being used as the carrier gas. The following conditions have been found suitable: a capillary column coated with a 1-µm layer of phase G2; the injection port temperature is maintained at 250
; the detector temperature is maintained at 300; and the column temperature is maintained at 150 and programmed to rise 10 per minute to 300. The area of the C11H14O peak is not less than 98% of the total peak area.
621) equipped with a flame-ionization detector, helium being used as the carrier gas. The following conditions have been found suitable: a capillary column coated with a 1-µm layer of phase G2; the injection port temperature is maintained at 250; the detector temperature is maintained at 300; and the column temperature is maintained at 150 and programmed to rise 10 per minute to 300. The area of the C11H14O peak is not less than 98% of the total peak area.
Refractive index 831:
1.5149 at 20.
831:
1.5149 at 20.
Boiling range:
between 105 and 107, at a pressure of 5 mm of mercury.
between 105 and 107, at a pressure of 5 mm of mercury.
Vanadium Pentoxide,
V2O5—181.88 [1314-62-1]—Fine, yellow to orange-yellow powder. Slightly soluble in water; soluble in concentrated acids and in alkalies; insoluble in alcohol.
V2O5—181.88 [1314-62-1]—Fine, yellow to orange-yellow powder. Slightly soluble in water; soluble in concentrated acids and in alkalies; insoluble in alcohol.
Assay—
Transfer about 400 mg, accurately weighed, to a 500-mL conical flask, and add 150 mL of water and 30 mL of dilute sulfuric acid (1 in 2). Boil the solution on a hot plate for 5 minutes, add 50 mL of water, and continue boiling until a yellow solution is obtained. Transfer the hot plate and the flask to a well-ventilated hood, and bubble sulfur dioxide gas through the solution for 10 minutes, or until the solution is a clear, brilliant blue color. Rinse the gas delivery tube into the flask with a few mL of water, then bubble carbon dioxide gas through the solution for 30 minutes while continuing to boil the solution gently. Cool the solution to about 80, and titrate with 0.1 N potassium permanganate VS to a yellow-orange endpoint. Perform a complete blank determination, and make any necessary correction. Each mL of 0.1 N potassium permanganate is equivalent to 9.095 mg of V2O5. Not less than 99.5% is found.
, and titrate with 0.1 N potassium permanganate VS to a yellow-orange endpoint. Perform a complete blank determination, and make any necessary correction. Each mL of 0.1 N potassium permanganate is equivalent to 9.095 mg of V2O5. Not less than 99.5% is found.
Vanadyl Sulfate,
VOSO4·xH2O (anhydrous)—163.00 [27774-13-6]—Blue, hygroscopic crystals. Slowly and usually incompletely soluble in water.
VOSO4·xH2O (anhydrous)—163.00 [27774-13-6]—Blue, hygroscopic crystals. Slowly and usually incompletely soluble in water.
Assay—
Accurately weigh about 400 mg of the dried test specimen obtained in the test for Water, and transfer with 15 to 20 mL of water into a beaker. Add 3 mL of sulfuric acid, cover the beaker with a watch glass, and heat on a steam bath until all dissolves. Cool, dilute with 125 mL of water, and titrate with 0.1 N potassium permanganate VS to the production of a pinkish color that persists for 1 minute: each mL of 0.1 N potassium permanganate is equivalent to 16.30 mg of VOSO4. Not less than 97% is found.
Water—
Dry about 1 g, accurately weighed, at 220 to constant weight: it loses not more than 50.0% of its weight.
to constant weight: it loses not more than 50.0% of its weight.
Pentavalent vanadium—
Heat 1 g, accurately weighed, with 50 mL of water and 5 mL of hydrochloric acid in a flask until dissolved. Cool, add 2 g of potassium iodide, insert the stopper, and allow to stand for 30 minutes. Add 50 mL of water, and titrate the liberated iodine with 0.1 N sodium thiosulfate VS, adding 3 mL of starch TS as the indicator. Correct for the volume of thiosulfate consumed by a blank. Each mL of 0.1 N thiosulfate is equivalent to 5.095 mg of vanadium (V). Not more than 0.5% is found, calculated on the dried basis.
Substances not precipitated by ammonia—
Dissolve 1.0 g by heating with 20 mL of water and 2 mL of hydrochloric acid. Dilute with water to about 75 mL, and neutralize to litmus paper with ammonia TS. Transfer the solution to a cylinder, slowly add 5 mL of ammonia TS and sufficient water to make 100 mL, and allow to stand overnight. Decant 50 mL of the supernatant through a filter, add 5 drops of sulfuric acid, evaporate to dryness, and ignite: the residue weighs not more than 10 mg (2.0%).
Vinyl Acetate,
CH3COOCH=CH2—86.09 [108-05-4]—Liquid.
CH3COOCH=CH2—86.09 [108-05-4]—Liquid.
Assay—
Inject an appropriate volume into a gas chromatograph (see Chromatography 621) equipped with a flame-ionization detector, helium being used as the carrier gas. The following conditions have been found suitable: a 0.25-mm × 30-m capillary column coated with a 1-µm layer of G2; the injection port temperature is maintained at 100; the detector temperature is maintained at 300; and the column temperature is maintained at 100 and programmed to rise 10 per minute to 150. The area of the CH3COOCH=CH2 peak is not less than 99% of the total peak area.
621) equipped with a flame-ionization detector, helium being used as the carrier gas. The following conditions have been found suitable: a 0.25-mm × 30-m capillary column coated with a 1-µm layer of G2; the injection port temperature is maintained at 100; the detector temperature is maintained at 300; and the column temperature is maintained at 100 and programmed to rise 10 per minute to 150. The area of the CH3COOCH=CH2 peak is not less than 99% of the total peak area.
2-Vinylpyridine,
C7H7N—105.14 [100-69-6].
C7H7N—105.14 [100-69-6].
Boiling range:
between 79 and 82, at 29 mm of mercury.
and 82, at 29 mm of mercury.
Density:
0.975 at 25.
.
Refractive index 831:
about 1.5490 at 20.
831:
about 1.5490 at 20.
Vinylpyrrolidinone(1-Vinyl-2-pyrrolidinone; 1-Vinyl-2-pyrrolidone; N-Vinylpyrrolidinone; N-Vinylpyrrolidone),
C6H9NO—111.14 [88-12-4]—Colorless liquid.
C6H9NO—111.14 [88-12-4]—Colorless liquid.
Assay—
Inject an appropriate volume into a gas chromatograph (see Chromatography 621) equipped with a flame-ionization detector, helium being used as the carrier gas. The following conditions have been found suitable: a 0.25-mm × 30-m capillary column coated with a 1-µm layer of G2; the injection port temperature is maintained at 250; the detector temperature is maintained at 300; and the column temperature is maintained at 100 and programmed to rise 10 per minute to 250. The area of the C6H9NO peak is not less than 99.0% of the total peak area.
621) equipped with a flame-ionization detector, helium being used as the carrier gas. The following conditions have been found suitable: a 0.25-mm × 30-m capillary column coated with a 1-µm layer of G2; the injection port temperature is maintained at 250; the detector temperature is maintained at 300; and the column temperature is maintained at 100 and programmed to rise 10 per minute to 250. The area of the C6H9NO peak is not less than 99.0% of the total peak area.
Water, Method 1 921:
not more than 0.1%, determined on 2.5 g, using a mixture of 50 mL of methanol and 10 mL of butyrolactone as the solvent.
921:
not more than 0.1%, determined on 2.5 g, using a mixture of 50 mL of methanol and 10 mL of butyrolactone as the solvent.
[Note—A suitable grade is available from Merck KGaA/EMD chemicals, catalogue number 8.08518.0250, www.emdchemicals.com. ]