Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Reinecke Salt (Ammonium Tetra(thiocyanato)diamminechromate(III) Monohydrate; Ammonium Diamminetetrakis(thiocyanato-N)chromate(1–)) Part 4, Monographs for Reagent Chemicals: General Descriptions, Specifications, and Tests eISBN: 9780841230460 Tom Tyner Chair, ACS Committee on Analytical Reagents James Francis Secretary, ACS Committee on Analytical Reagents
ABSTRACT This monograph for Reinecke Salt provides, in addition to common physical constants, a general description including typical appearance, applications, and aqueous solubility. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Assay, Insoluble in Dilute Hydrochloric Acid, Sensitivity. Special caution is advised for the handling or testing of this substance.
NH4[Cr(SCN)4(NH3)2] • H2O
Formula Wt 354.42
CAS No. 13573-16-5
C a u t i o n : Aqueous solutions of Reinecke salt decompose slowly with the evolution of hydrogen cyanide gas. Decomposition is rapid above 65 °C.
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . dark red solid Applications . . . . . . . . . . . . . . . . . . . . . . . . precipitant for primary and secondary amines, proline, hydroxyproline, and certain amino acids Aqueous solubility . . . . . . . . . . . . . . . . . . . . soluble in hot water; sparingly in cold
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . >93.0% NH4[Cr(SCN)4(NH3)2] · H2O Insoluble in dilute hydrochloric acid . . . . . . . . ≥0.05% Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . Passes test
© 2017 American Chemical Society
A
DOI:10.1021/acsreagents.4317 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By gravimetric determination as mercury salt). Weigh accurately about 0.5 g, and dissolve in 100 mL of water containing 0.5 mL of hydrochloric acid. Add a hot solution containing 0.5 g of mercuric acetate dissolved in a mixture of 140 mL of water and 10 mL of hydrochloric acid. Digest on a hot plate (~100 °C) for 5 min, filter through a tared, preconditioned porcelain filtering crucible, and wash several times with hot water. The precipitate can be dried at 105 °C and weighed as Hg[Cr(SCN)4(NH3)2]2:
Alternatively, the precipitate can be ignited in a hood and heated to constant weight at 600 °C as Cr2O3:
Insoluble in Dilute Hydrochloric Acid Dissolve 2.0 g in 200 mL of dilute hydrochloric acid (1:99), heat to boiling, and digest in a covered beaker on a hot plate (~100 °C) for 1 h. Filter through a tared filtering crucible, wash thoroughly with water, and dry at 105 °C.
Sensitivity Dissolve 50 mg in 10 mL of water. Add 0.2 mL of this solution to 1 mL of a solution of 10 mg of choline chloride in 20 mL of water, and shake gently. A distinct red precipitate should form within 10 s.
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4317 ACS Reagent Chemicals, Part 4
