Halides isothiouronium salts

Thiourea Alkyl halide Isothiouronium salt Urea Thiol... 

Before the synthesis of the pseudoureas was published, Bernthsen and Klinger [6] reported a pseudothiourea synthesis involving the reaction of thioureas with alkyl halides. This reaction was briefly reviewed by Dains [16] and Stieglitz [49, 50], and it found many commercial applications [51-53]. The preparation of isothiouronium salts by the direct action of thiourea and halogen acids on alcohols (primary, secondary, and tertiary) was reported by Stevens [8] and further developed by Johnson and Sprague [54, 55] (Eq. 25). 

Thiols may be prepared from the corresponding alkyl halide by reaction with thiourea followed by treatment of the isothiouronium salt with base. 

The analysis of isothiouronium salts, which are conveniently formed by reacting alkyl halides with thiourea, provide a way to study alkyl halides . The H NMR spectrum of s-butylisothiouronium chloride and bromide exhibited enantiomeric discrimination in the presence of [Eu(tfc)3(fod)] The enantiomeric purity of several alkyl methyl phenyl sulfonium ions (73) under conditions of slow inversion was determined using either [Eu(tfc)3(fod)] or [Eu(tfc)4] It was possible to study the inversion barrier by variable-temperature studies in the presence of the shift reagent. 

The preparation of thiols involves nncleophilic snbstitntion of the Sn2 type on alkyl halides and nses the reagent thiourea as the sonrce of snlfnr. Reaction of the alkyl halide with thionrea gives a compound known as an isothiouronium salt in the hrst step. Hydrolysis of the isothiouronium salt in base gives the desired thiol (along with urea) ... 

Section 15.13 Thiols, compounds of the type RSH, are prepared by the reaction of alkyl halides with thiourea. An intermediate isothiouronium salt is formed, which is then subjected to basic hydrolysis. 

Sulfonic acid chlorides from halides via isothiouronium salts s. 18, 562 Hal SO2GI... 

The sulfur atom of thiourea is a better source of a sulfur nucleophile in a reaction that will convert a alkyl halide to a thiol. Thiourea reacts with alkyl halides to give an isothiouronium salt. Subsequent hydrolysis of this salt in the same reaction vessel yields a thiol. 

The reaction of halides and subsequent alkaline hydrolysis without isolation of the intermediate isothiouronium salt has been used for the synthesis of thiols. aa -Dimercapto-o-xylene has been obtained from the corresponding bromide in 97% yield. ... 

Tetrakis chelate anions formed when either a silver or potassium P-diketonate is mixed with a lanthanide tris P-diketonate are effective shift reagents for organic-soluble salts. Adding an organo-halide or fluoroborate salt leads to precipitation of silver halide or potassium fluoroborate, resulting in an organic-soluble ion pair. These reagents have been used to enantiomerically resolve the spectra of chiral isothiouronium and sulfonium ions. 

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