Lithium thiocyanate solution

Lithium thiocyanate solutions in nonaqueous solvents have been extensively studied by means of vibrational spectroscopy. The high solubility of this salt in many organic solvents and the well-understood vibrational behavior of the thiocyanate anion (see, for instance. 

IQ. To determine the concentration of chloride ion, - a 5-mL aliquot of the methyl lithium solution is cautiously added to 25 ml of water and the resulting solution is acidified with concentrated sulfuric acid and then treated with 2-3 ml of ferric ammonium sulfate [Fe(NH4)( 04)2 12 H2O] indicator solution and 2-3 ml of benzyl alcohol. The resulting mixture is treated with 10.0 mL of standard aqueous 0.100 M silver nitrate solution and then titrated with standard aqueous 0.100 H potassium thiocyanate solution to a brownish-red endpoint. 

Lithium thiocyanate, LiCNS.—The thiocyanate is obtained by neutralizing an aqueous solution of thiocyanic acid with lithium carbonate, and evaporating.7 It forms very deliquescent plates, readily soluble in alcohol. 

Cancer pagurus cuticle can be dispersed in hot, aqueous solutions of lithium thiocyanate and be reprecipitated without separating the chitin and protein components. The stability of the complex under these conditions would suggest the presence of primary bonding. Thus, some ehitin-protein bonding does exist in arthropod cuticle, but its exact nature and its physiological significance or its involvement in chitin biosynthesis (or both) remain uncertain. 

Lithium thiocyanate (lithium rhodanide) [556-65-0] M 65.0, pK -1.85 (for HSCN). It crystallises from H2O as the dihydrate, but on drying at 38-42° it gives the monohydrate. It can be purified by allowing an aqueous solution to crystallise in a vacuum overP20s. The crystals are collected, dried out in vacuo at 80°/P2Os... 

Another type of dissolution reagents is represented by concentrated chaotropic salt solutions like hthium bromide (LiBr) (Ambrose et al., 1951), lithium thiocyanate (LiSCN) (Sridhara et al., 1973), calcium chloride (CaCl2) (Ajisawa, 1998) based on either only water or alcohol—aqueous solutions such as CaCb—ethanol—H2O (Ajisawa, 1998 Chen et al.,... 

Figure 19 Association degree of lithium thiocyanate in several nonaqueous solvents (0.1 M solution). Abbreviations AcOEt = ethyl acetate BusO = butyl ether DEC = diethyl carbonate DMA = A, A-dimethylacetamide DMC = dimethyl carbonate DMM = dimethoxymethane HMPT = hexa-methylphosphotriamide i-Pr20 = isopropyl ether MeN02 = methylene nitrate TBP = tributyl phos-pate TMP = trymethyl phosphate TMU = tetrametylurea. (Adapted from Ref. 204.)...

HCl [134b,c]. The 7-form is converted into the a-form by treatment with a saturated aqueous solution of lithium thiocyanate [134c]. These transformations appear to be irreversible. P- and 7-Chitin occur where the properties of the polysaccharide require flexibility and toughness [134d]. 

The first reported synthesis of acrylonitrile [107-13-1] (qv) and polyacrylonitrile [25014-41-9] (PAN) was in 1894. The polymer received Htde attention for a number of years, until shortly before World War II, because there were no known solvents and the polymer decomposes before reaching its melting point. The first breakthrough in developing solvents for PAN occurred at I. G. Farbenindustrie where fibers made from the polymer were dissolved in aqueous solutions of quaternary ammonium compounds, such as ben2ylpyridinium chloride, or of metal salts, such as lithium bromide, sodium thiocyanate, and aluminum perchlorate. Early interest in acrylonitrile polymers (qv), however, was based primarily on its use in synthetic mbber (see Elastomers, synthetic). 

Aqueous salt solutions such as saturated 2inc chloride [7646-85-7] or calcium thiocyanate [2092-16-2] can dissolve limited amounts of cellulose (87). Two non-aqueous salt solutions are ammonium thiocyanate [1762-95-4]— uoamonia. and lithium chloride /744Z-4/A/—dimethyl acetamide [127-19-5]. Solutions up to about 15% can be made with these solvents. Trifluoroacetic acid [76-05-17—methylene chloride [75-09-2] and /V-methy1morpho1ine N-oxide [7529-22-8]—(92—94) are two other solvent systems that have been studied (95). 

Most linear celluloses may be dissolved in solvents capable of breaking the strong hydrogen bonds. These solutions include aqueous solutions of inorganic acids, calcium thiocyanate, zinc chloride, lithium chloride, ammonium hydroxide, iron sodium tartrate, and cadmium or copper ammonium hydroxide (Schweitzer s reagent). The product precipitated by the addition of a nonsolvent to these solutions is a highly amorphous, regenerated cellulose. 

A solution or suspension of 0.22 mol of the lithium or sodium alkynylide in 300 ml of liquid ammonia is prepared as described on p. 20. The disulfide, thiosulfonate or thiocyanate (0.20 mol, diluted with 50 ml of Et20, is added dropwise over 10 min with efficient stirring. In many cases a rather thick suspension is formed an additional volume of-100 ml of liquid... 

The, S n2 reaction between lithium isothiocyanate ion pair and methyl fluoride has been calculated at the MP2(full)/6-31H-G //HF/6-311- -G level of theory in the gas phase and in acetone using the PCM model.108 Both the gas phase and acetone reactions occur with inversion, rather than retention, of configuration. However, the transition states and products are different in the gas phase and in solution methyl thiocyanate is formed in the gas phase by transition state (72) whereas methyl isothiocyanate is formed much more slowly in acetone via the looser transition state (73). 

Silver nitrate forms double salts with the halides, cyanide, and thiocyanate of silver.5 It also yields with silver sulphide a compound containing equimolecular proportions of the two salts, prepared as a yellowish-green precipitate by the action of hydrogen sulphide on a concentrated solution of silver nitrate. It forms other double salts with the nitrates of lithium and sodium,8 potassium,7 ammonium,8 and thallium.9 The solution of silver nitrate in ammonium hydroxide yields rhombic prisms, AgN03,2NH3, isomorphous with silver nitrate.10... 

Aqueous salt solutions such as saturated zinc chloride or calcium thiocyanate can dissolve limited amounts of cellulose [131]. Two nonaqueous salt solutions with a lengthy history are ammonium thiocyanate/ammonia and dimethylacetamide/lithium chloride (DMAc/LiCl). Solutions up to about 15% can be prepared with these solvents. DMAc-LiCl has been used for molecular weight determinations of cotton [135] (see Section 1.5.2). 

When it is not possible to employ potassium chloride solution, e.g., if one of the junction solutions contains a soluble silver, mercurous or thallous salt, satisfactory results can be obtained with a salt bridge containing a saturated solution of ammonium nitrate the use of solutions of sodium nitrate and of lithium acetate has also been suggested. For non-aqueous solutions, sodium iodide in methyl alcohol and potassium thiocyanate in ethyl alcohol have been employed. 

The properties of irans-RhCl(CO)(PPh3)2 (m.p. 195-197°) and /mns-RhCl(CO)(AsPh3)2 (m.p. 242-244°) have been given. The chlorides can be rapidly converted to the corresponding bromides, iodides, or thiocyanates by the interaction in acetone solutions at room temperature with lithium bromide, sodium iodide, or potassium thiocyanate, respectively. Alternatively, rhodium (III) chloride can first be converted to the bromide or iodide by boiling the ethanolic solution with a ca. fivefold excess of lithium bromide or iodide. 

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