Sulfonate esters alcohol conversion into

Conversion of the alcohol into a sulfonate ester followed by an SN2 substitution using a halide nucleophile is another method that is commonly employed. Examples are provided in the following equations ... 

The sulfonate ester method requires two steps for the conversion of an alcohol into an alkyl chloride. A reagent that can accomplish this transformation in one step is thionyl chloride, SOCl2. In a reaction very similar to the formation of sulfonate esters, this reagent replaces the hydrogen of the alcohol with a group that makes the oxygen a... 

Alcohols are important for organic s)mthesis, especially in situations involving alkenes. The alcohol might be the desired product, or the OH group might be transformed into another functional group via halogenation, oxidation, or perhaps conversion to a sulfonic ester derivative. Formation of an alcohol from an alkene is particularly powerful because conditions can be chosen to produce either the Markovnikov or non-Markovnikov product from an unsym-metrical alkene. 

MECHANISM FOR THE CONVERSION OF AN ALCOHOL INTO A SULFONATE ESTER... 

Sulfonylation of Alcohols. Primary and secondary alcohols could be mesylated, tosylated, or p-nitrobenzenesulfonylated in the presence of Ag20 and KI (eq 21). It was demonstrated that KI accelerates the reaction presumably by converting the sulfonat-ing reagent into a highly reactive sulfonyl iodide. Typically 1.5 mol equiv of Ag20 was sufficient for an efficient conversion, however, occasionally a twofold excess was required. It was noted that since the reaction does not require aqueous work-up, subsequent nucleophilic substitution of the sulfonate ester could be performed without the necessity of isolating the intermediates. 

Organic sulfonyl chlorides are important reagents in organic chemistry for the activation of alcohol groups by their conversion into the corresponding sulfonate esters 17 which are then easily displaced by nucleophiles since the sulfonate moiety is an excellent leaving group (Equation 14). ... 

The preparation of alkyl halides by substitution reactions usually starts from alcohols because alcohols are widely available. Hydroxide ion is a poor leaving group, so the OH must first be converted into a better leaving group, either by protonation in acid or by conversion to a sulfonate or similar ester (see Section 8.9), as illustrated in the following equations ... 

Air, the cheapest oxidant, is used only rarely without irradiation and without catalysts. Examples of oxidations by air alone are the conversion of aldehydes into carboxylic acids (autoxidation) and the oxidation of acyl-oins to a-diketones. Usually, exposure to light, irradiation with ultraviolet light, or catalysts are needed. Under such circumstances, dehydrogenative coupling in benzylic positions takes place at very mild conditions [7]. In the presence of catalysts, terminal acetylenes are coupled to give diacetylenes [2], and anthracene is oxidized to anthraquinone [3]. Alcohols are converted into aldehydes or ketones with limited amounts of air [4, 5, 6, 7], Air oxidizes esters to keto esters [3], thiols to disulfides [9], and sulfoxides to sulfones [10. In the presence of mercuric bromide and under irradiation, methylene groups in allylic and benzylic positions are oxidized to carbonyls [11]. 

Polymer-bound reagents for silylation have been reported. Murata and Noyori treated Nation, a perfluorinated resin-sulfonic acid, with trimethylsilyl chloride to afford a polymer-bound trimethylsilyl ester that functions as a polymer-bound equivalent of trimethylsilyl trifluoromethanesulfonate, converting alcohols, eth-anethiol and diethylamine into the corresponding silylated compounds in high yields (Scheme 6.16) [70]. Acetic acid could also be silylated, albeit with moderate conversion. The corresponding polystyrene-bound reagent is commercially available. 

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