Sulfur tetrafiuoride

Reaction of Carbonyl Compounds with Sulfur Tetrafiuoride-Hydrogen Fluoride... 

Sulfur tetrafiuoride is an important industrial fluorinating agent for... 

Caution This procedure should be conducted in a good hood to avoid exposure to sulfur tetrafiuoride. Protective gloves should be worn when handling diethylaminosulfur trifluoride since this material can cause severe HF burns. 

The recent discovery of a convenient synthesis of sulfur tetrafiuoride from sulfur dichloride and sodium fluoride in acetonitrile86 invited the application of this reagent in fluorination reactions. Hasek, Smith and Engelhardt87 showed that carboxylic acids and their derivatives can be converted into trifluoromethyl derivatives and that aldehydes and ketones are converted into em-difluoro compounds. They also observed that the reaction was acid... 

The stereochemical outcome of the overall reaction is interpreted as the consequence of a stepwise fluorination.4-5 The first fluorine comes in via an SN2-type substitution of the cyclic intermediate 4 with inversion. The second fluorine is introduced with retention from the intermediate 7, which is formed by the action of hydrogen fluoride and sulfur tetrafiuoride on intermediate fluorosulfite 5 via 6. 

Mild treatment of dimethyl (+ )-r.-tartratc with sulfur tetrafiuoride alone gives the isolable intermediate 2-fluoro-l, 2-bis(methoxycarbonyl)ethyl fluorosulfite (5) in 98% yield.4 This can be hydrolyzed to dimethyl (- )-(2.S,3.S)-2-fluoro-3-hydroxysuccinate (6) in 97% yield. Hence, by proper choice of the reaction conditions, one or two hydroxy groups can be selectively substituted by fluorine in dialkyl tartrates.4... 

Thereare a limited number of examples of the reaction of nitro alcohols with sulfur tetrafiuoride. In each case the reaction was performed with additional hydrogen fluoride present. With these modifications relatively drastic conditions must be used and yields are low to moderate, depending on the substrate (Table 1). 

Table 1. Fluorination of Nitro Alcohols with Sulfur Tetrafiuoride...

Polyfluorinatcd primary alcohols of the general formulae CF3(CF2)nCH2OH and CHF2(CF2)nCH2OH can be fluorinated with sulfur tetrafiuoride to give products 1 in one step in good yield.14... 

The standard enthalpy change for the formation of sulfur tetrafiuoride (SF4) from the gaseous elements at 298 K follows the thermochemical equation... 

Practice Exercise Write chemical formulas for the following molecular compounds (a) sulfur tetrafiuoride and (b) dinitrogen pentoxide. 

Hydrogen fluoride is produced worldwide in 10 ta by reaction of fluorspar with sulfuric acid (equation 1). The reaction is endothermic (AF/298 = 59kJmol ) and is carried out in rotary furnaces that produce up to 45td . The crude HF is scrubbed by H2SO4 and purified further by distillation as required. Silicon tetrafiuoride is a by-product from silicate impurities (equation 2) and is recovered as H2SiFe (equations). Another by-product, CaS04, is used in cement production and other applications. ... 

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