Reineckate salt

Ammonium reineckate (Reineckate salt) [13573-16-5] M 345.5, m 270-273 (dec). Crystd from water, between 30° and 0°, working by artificial light. Solns of reineckate decompose slowly at room temperature in the dark and more rapidly at higher temperatures or in diffuse sunlight. 

Strongly basic antibiotics may be precipitated by formation of the coloured reineckate salt which may then be determined spectrophotometri-cally 65. Bickfordl66 dissolved the precipitated neomycin reineckate in acetone and has successfully used this procedure to assay neomycin extracted from topical formulations. Roushdi et al 73 preferred to oxidise the precipitate with potassium permanganate and then colorimetrically estimate the chromate produced with diphenylcarbazide. 

The method of protein hydrolysis was important acid hydrolysis caused destruction of tryptophan but alkaline treatment gave even greater losses of other amino acids especially cystine. The amino acids were usually separated by then standard chemical procedures based on differences in solubility, selective precipitation by agents such as Reinecke salt (proline and hydroxyproline), or flavianic acid (arginine). 

Biosensors employing the NAD+-dependent LDH enzyme [59-61] require an immobilisation procedure for the deposition of the mediator and water-soluble cofactor. The MB mediator was rendered water-insoluble by the use of its Reinecke salt in two studies [59,60], and by electropolymerisation with the enzyme in an another study [61] both of these approaches required an operating potential close to 0 V. 

The new Reinecke-salt-like compounds K[Cr(NCS)4L ] (n = 1 or 2 L = o- or m-phenylenediamine, respectively) have been prepared by the reaction of K3[Cr-(NCS)6] with L and their thermal stabilities investigated.179 Diquinolino- and di-iodoquinolino-silver(i) iodide salts of the anions [Cr(NCS)6]3- and [Cr(NCS)4L2] (L = aniline, o- or p-toluidine) have been prepared and characterized.180 Chro-mium(m) thiocyanato-complexes with biguanide derivatives, K[Cr(NCS)4L] [L = phenyl-, p-chlorophenyl-, tolyl-, or 1-(p-chlorophenyl-5-isopropyl)biguanide], have been prepared by the reaction of K3[Cr(NCS)6] with L in anhydrous EtOH and their i.r. and electronic spectra reported.181 cis- and trans-[Cr(en)2(NH3XNCS)]2 + have been prepared and both shown to have a Amax value at 476 nm, but with the expected relative magnitudes of s values, cis > trans, as 120 to 80.182 The thermal decompositions of the salts [Cr(NH3)6 x(NCS)x](NCS)3 x (x = 0. 1. or 2) have been characterized. Under d.t.a. conditions [Cr(NH3)6](NCS)3 changes stepwise to [Cr(NH3)5(NCS)](NCS)2, trans-[Cr(NH3)4(NCS)2](NCS), and finally to merfac-[Cr(NH3)3(NCS)3].183... 

The resulting crystals are collected and the mother liquor employed for a second similar extraction of the residue at 6o°. This yields a further crop of crystalline Reinecke salt. The mother liquor is finally concentrated to 250-300 cc. by evaporation at 40-50° under reduced pressure, when a small third crop (12-13 S-) is obtained. The total yield of air-dried crystals is 250-275 g. (52-57 per cenL of the theoretical amount) (Note 7). 

The filtrate, which consists largely of unchanged ammonium thiocyanate and its decomposition products, contains too little Reinecke salt to repay further treatment. 

Reinecke salt decomposes in aqueous solution with formation of a blue color and free hydrogen cyanide. At room temperature this decomposition occurs in about two weeks, and above 65° it takes place quite rapidly. A similar decomposition takes place in boiling alcohol. 

Reinecke salt is of value as a precipitant for primary and secondary amines, proline and hydroxyproline, and certain amino acids.1... 

The Morland salt, which is soluble in acetone, contains a small proportion of a colorless sulfur compound insoluble in hot water. It can be partially converted into Reinecke salt by treatment in dilute ammonia solution with a large excess of ammonium chloride, but the amounts so obtainable are unprofitably small. 

Reinecke salt has been prepared by adding either potassium dichromate2 or ammonium dichromate ia to fused ammonium thiocyanate. 

The first chemical work on calabash curare was carried out in 1897 by Boehm (8), who isolated a highly active amorphous material which was named curarine. This was soluble in water and insoluble in ether, so it is probable that Boehm was handling a mixture of crude quaternary alkaloids. Much later (1935), King described (9) the preparation of an equally active amorphous quaternary iodide from the bark of S. toxifera. However, the first isolation of well-characterized crystalline alkaloids was achieved by H. Wieland and his school (10-13). Calabash curares were extracted with methanol, and the water-soluble quaternary alkaloids in the extract were precipitated as the reineckate salts this mixture was then fractionated by adsorption chromatography on alumina. The various reineckate fractions so obtained were converted into the corresponding chlorides by successive treatment with equivalent quantities of silver sulfate and barium chloride some of the quaternary alkaloids then crystallized as the chlorides or as the picrates. C-Curarine1... 

Phenylazobenzenesulfonyl chloride. Reinecke salt. Silicone isocyanate. 

The sample is dissolved in HC1 and treated with 1% Reinecke salt. The precipitate is washed, dried at 105°C and weighed to constant weight or the dried precipitate may be dissolved in acetone for colorimetric determination at 530 mp36. 

Reinecke salt. (ammonium tetrathio-cyanodiammonochromate ammonium reinec-... 

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