Thiocyanogen SCN

Ag" (precipitate of AgSCN) and (red colouration). Photographic sulphur sensitizers. With oxidizing agents (MnOj, Br ) give thiocyanogen, (SCN)2, which polymerizes above O C. 

Thiocyanogen [(SCN)2, 5°, 4 h, 40% yjeld] selectively oxidizes an 5-tri-phenylmethyl thioether to the disulfide (RSSR) in the presence of an 5-di-phenylmethyl thioether. ... 

The monothioacetal is also stable to 12 N hydrochloric acid in acetone (used to remove an TV-triphenylmethyl group) and to hydrazine hydrate in refluxing ethanol (used to cleave an A -phthaloyl group). It is cleaved by boron trifluoride etherate in acetic acid, silver nitrate in ethanol, and tiifluoroacetic acid. The monothioacetal is oxidized to a disulfide by thiocyanogen, (SCN)2- ... 

An S-2-tetrahydropyranyl monothioacetal is oxidized to a disulfide by iodine or thiocyanogen, (SCN)2- ... 

Draw two possible structures for thiocyanogen, (SCN)2, and comment on the relative stability of the structures you draw. 

The hydrolysis of thiocyanogen (SCN)2 in warm base yields sulfate, cyanide, and thiocyanate ions. Show how this hydrolysis is in conformity with the picture of the —SGN as a pseudo-halogen group. (Hint recall the hydrolysis of the halogens under similar conditions.)... 

The title compounds are usually obtain in a straightforward manner and in almost quantitative yields by alkane elimination process between a dialkylzinc compound ZnRs and the desired thiol R SH or selenol R SeH species (equation 18). This reaction works equally well in hydrocarbon solvent or neat solution. If thiocyanogen (SCN)2 is used as the reagent, then alkylzinc thiocyanate derivatives (RZnSCN) are obtained. ... 

Thiocyanogen, (SCN)2, is released by the action of bromine on AgSCN suspended in ether ... 

Also the trityl group was applied for the masking of SH functions. The sulfides were prepared by the reaction of the thiol with trityl chloride (75% yield) or from trityl alcohol and the thiol in the presence of anhydrous TFA (85-90% yield). The cleavage of this group can be carried out under several conditions (Scheme 58). It is sensitive to acids (e.g. trifluoroacetic acid/ethanethiol 1 1) and to heavy metals. Thiocyanogen (SCN)2 oxidizes 5-trityl ethers to the disulfides and iodine converts 5-tritylcy -teine derivatives to cystine structures. 

Phenols and primary, secondary, and tertiary aromatic amines with free ortho- and/or /wra-positions react readily with thiocyanogen, (SCN)2. SCN enters the position para to the OH or NR2 group, or, if that is occupied, into the orfAtf-position.11,12 In the later case subsequent ring closure may be easy.14,760 For instance, / -toluidine gives 6-methylbenzo[A]thiazole-2-amine, and etyhl / -aminobenzoate gives ethyl 2-aminobenzo[Z ]thiazole-6-carboxylate. 

Johnstone and Plimmer (1971) reviewed the constituents of tobacco and tobacco smoke in 1959 and listed CO, CO2, carbonyl sulfide (COS), NH3, carbon disulfide (CSj), cyanogen [(CN)2J, hydrogen cyanide (HCN), thiocyanogen [(SCN)2l, NO, and numerous small saturated and unsaturated... 

There exist three fundamental ways to prepare OSCN (1) hydrolysis of thiocyanogen, (SCN)2 in aqueous base (2) enz5une-catalyzed oxidation of SCN by H2O2 and (3) oxidation of SCN by electrophilic halogenating agents. The advantages and disadvantages of each of these methods will be discussed next. 

By analogy to halogens, thiocyanogen (SCN)2 is moderately stable. It can be prepared as colorless crystals by suspending AgSCN in SO2 at —20°C and oxidizing the coordinated SCN with Br2 or I2 48) ... 

The direct replacement of a hydrogen atom by a thiocyano group through the use of thiocyanogen, (SCN)2, is commonly termed thiocya-nation. This replacement reaction is limited practically to aromatic... 

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