Lithium thiocyanate

Lithium thiocyanate (lithium rhodanide) [556-65-0] M 65.0. 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 soln to crystallise in a vac over P2O5. The crystals are collected, dried out in vacuum at 80°/P2O5 in a stream of pure N2 at 110°. [7C5 1245 1936]. 

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. 

The ring contraction of 1,2-cyclobutanediones is promoted either by acids or by bases in protic media". The reaction products are a-hydroxycyclopropanecarboxylic acids or the corresponding esters. Rearrangements of some 2-alkylidenecyclobutanols to cyclopropyl carbonyl compounds are also known. 1,2-Epoxycyclobutanes afford cyclopropanecarbal-dehydes or cyclopropyl ketones under the catalytic action of protic acids, lithium iodide or lithium thiocyanate (equation 107) . Under the latter conditions, the reaction... 

The use of aluminium chloride leads to some concomitant cyclobutanone formation, when possible. Lithium iodide and lithium thiocyanate have also been used as catalysts, and in these cases the reaction occurs stereospecifically with net retention of configuration at the migration terminus, presumably via the intermediacy of a lithium 2-iodocyclobu-toxide (equation 170) ... 

The first set of conditions used for ring contraction of a 1,2-epoxycyclobutane (sulfuric acid) also gave ring-opened products. Extensive studies have shown that careful use of protic acids or lithium iodide and lithium thiocyanate gives mainly cyclopropyl products. 

Reaction. with Lithium Thiocyanate. To LiSCN (153 mg, 2.3 mmol) in anhyd Et O (1 mL) was added exo-7,8-epoxybicyclo[4.2.0]octane (166 mg, 1.3 mmol). The flask was stoppered and stirred at 4L C for 34 h. Workup as described above gave the product yield 150 mg (90%), whose H NMR spectrum was consistent with that of known bicyclo[4.1.0]heptane-en<7o-7-carbaldehyde and displayed no cxo-aldchyde signal at 5 = 9.1. Air oxidation of the carbaldehyde gave an acid identical with authentic bicyclo[4.1.0]hep-tane-enrfo-7-carboxylic acid. ... 

An interesting formation of partially hydrogenated benzothiazoles involves the reaction between 1-trimethylsilylcyclohexene (and its 4-t-butyl derivative) and iodine/lithium thiocyanate. The reaction occurs in a highly regio- and stereoselective manner to give the adducts (100 R = H or CMca), which subsequently react with KOH in MeOH to give (101). ... 

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