Alkyl halides, primary, oxidation carboxylic acids

The catalytic system tranx-[Ru(0)2 (105(0H) 3] /K(I0 )/aq. KOH or aq. Aliquat converted primary alcohols [554, 555] and primary activated alkyl halides [555] to carboxylic acids, while secondary alcohols [554, 555], and secondary alkyl halides were oxidised to ketones [555]. As with catalytic oxidations by aqueous [RuO ] double bond cleavage occurs [555]. 

Several examples have been reported of the use of palladium-mediated oxidation reactions of alcohols and alkyl halides. Palladium(II) acetate in the presence of iodobenzene converts primary and secondary alcohols into carbonyl compounds under solid-liquid two-phase conditions [20], However, other than there being no further oxidation to carboxylic acids, the procedure has little to commend it over other methods. It is relatively slow with reaction times in the order of 2 days needed to achieve yields of 55-100%. 

This can be used for oxidations in aqneons base of primary alcohols, aldehydes, activated alkyl halides, ctT-diols and nitroalkanes to carboxylic acids, and of secondary alcohols and secondary halides to ketones. 

Primary alkyl halides (chlorides, bromides, and iodides) can be oxidized to aldehydes easily and in good yields with dimethyl sulfoxide.311 Tosyl esters of primary alcohols can be similarly converted to aldehydes,312 and epoxides313 give a-hydroxy ketones or aldehydes.314 The reaction with tosyl esters is an indirect way of oxidizing primary alcohols to aldehydes (9-3). This type of oxidation can also be carried out without isolation of an intermediate ester The alcohol is treated with dimethyl sulfoxide, dicyclohexylcarbodiimide (DCC),315 and anhydrous phosphoric acid.316 In this way a primary alcohol can be converted to the aldehyde with no carboxylic acid being produced. 

The typical reactions of the alcohol group include their conversion to ethers and esters by reaction with alkyl halides and with acid chlorides or anhydrides, respectively (Scheme 6.2). The benzyl ether group is readily cleaved by hydrogenolysis and is often used as a protecting group for alcohols. Primary alcohols are oxidized initially to the aldehyde and then to the carboxylic acid. 

The oxidation of primary alkyl halides to carboxylic acids is accomplished on incubation of long-chain aliphatic fluorides, chlorides, bromides, and iodides with the yeast Torulopsis gropengiesseri [1086,1087] (equation 200). The biooxidation starts at the terminal methyl groups and gives w-halogenoalkanoic acids, which are ultimately converted to a,oj-dicarboxylic... 

Nitriles are commonly available from aldoximes (aldehydes) and amides (carboxylic acids) by dehydration, from alkyl halides by nucleophilic substitution, and from primary amines by oxidation. It is therefore not surprising that these... 

Primary alkyl halides have also been oxidized to provide the corresponding carboxylic acids. On treatment with concentrated nitric acid, /raws-2,3-bis(iodomethyl)-p-dioxane provides trans-p-dioxane-2,3-dicarboxylic acid in 73% yield." ... 

Sulfonic esters are most frequently prepared by treatment of the corresponding sulfonyl halides with alcohols in the presence of a base. This procedure is the most common method for the conversion of alcohols to tosylates, brosylates, and similar sulfonic esters. Both R and R may be alkyl or aryl. The base is often pyridine, which functions as a nucleophilic catalyst, as in the similar alcoholysis of carboxylic acyl halides (16-61). Propylenediamines have also been used to facilitate tosylation of an alcohol. Silver oxide has been used, in conjunction with KI. Primary alcohols react the most rapidly, and it is often possible to sulfonate selectively a primary OH group in a molecule that also contains secondary or tertiary OH groups. The reaction with sulfonamides has been much less frequently used and is limited to A,A-disubstituted sulfonamides that is, R— may not be hydrogen. However, within these limits it is a useful reaction. The nucleophile in this case is actually RO . However, R may be hydrogen (as well as alkyl) if the nucleophile is a phenol, so that the product is RS020Ar. Acidic catalysts are used in this case. Sulfonic acids have been converted directly to sulfonates by treatment with triethyl or trimethyl orthoformate, HC(OR)3, without catalyst or solvent and with a trialkyl phosphite, P(OR)3. ... 

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