Sodium iodide bromides into alkyl iodides

In what appears, initially, to be a closely similar reaction, acid chlorides react with alkyl halides under solidtliquid two-phase conditions using sodium hydrogen carbonate in the presence of sodium iodide and tetra-n-butylammonium bromide [45]. Although the mechanism is not clear, it has been proposed that the acid chloride is initially converted into the carboxylate anion. It is also probable that the halogen interchange between the sodium iodide and the alkyl halides enhances their reactivity. Although the yields are high, the availability of the alkyl halides and alcohols are usually similar and there appears to be little to commend this process over the catalysed reaction of the acid chlorides with the alcohols. 

Sodium iodide in acetone is a reagent that converts alkyl chlorides and bromides into alkyl iodides by an SN2 mechanism. Pick the alkyl halide in each pair that is more reactive toward SN2 displacement. 

Dialkylation of malonic ester proceeds in most cases almost as readily as monoalkylation. Diethyl ethylmalonate is alkylated equally well by s-octyl and n-butyl halides. Di-n-propylmalonic ester is prepared in one step from malonic ester and n-propyl bromide. Methylmalonic ester is alkylated by /3-phenylethyl bromide, and even a-naphthyl-malonic ester may be further alkylated by n-alkyl iodides. Difficulty is encountered, however, in introducing two s alkyl groups into malonic ester. A 23% yield of diisopropylmalonic ester is obtained from iso-ptopylmalonic ester, sodium triphenylmethide, and isopropyl iodide. ... 

Aliphatic primary halides—chlorides, bromides, and especially iodides—are converted into aldehydes by treatment with dimethyl sulfoxide [998, 999, 1000] or trimethylaniine oxide [993], The reactivity of alkyl chlorides and bromides is increased by converting them in situ to alkyl iodides by the addition of sodium iodide into the reaction mixtures [999] (equation 188). 

A further synthesis of primary aliphatic amines was developed by Dele-pine 464 he alkylated urotropine to the monoquaternary salt and cleaved that by alcoholic hydrochloric acid. Chlorides and bromides often react very slowly with urotropine, but they can be converted in situ into the iodides by adding an equivalent amount of sodium iodide. 

Sodium cyanoborohydride in hexamethylphosphoramide selectively reduces alkyl iodides, bromides, and toluene-/ -sulphonates to the corresponding hydrocarbons aldehydes, ketones, etc., are not attacked. This allows the direct conversion of an alcohol into the corresponding hydrocarbon (Scheme 125) by hydride attack on the intermediate phosphite salt (197). 

Alkyl halide (10 — 25 mg) is mixed with 0.5 ml of a 2% acetonic thiourea solution and heated in a sealed glass ampoule in a water bath for various time intervals iodides, 1 hr bromides, 2 hr chlorides (if the mixture was additioned with 10 mg of sodium iodide as catalyst) 3 hr. After cooling, the ampoule is opened and the contents transferred into a small test tube, and the solvent is evaporated on a water bath. The residue is dissolved in two drops of water and mixed by dropwise addition and shaking with 1 ml 2% aqueous sodium 3,5-dinitrobenzoate solution. The separatedamo rphous product is dissolved by immersing the test tube into a hot water bath, and is then allowed to crystallize by slow cooling. The product is recrystallized from 0.5 — 1 ml of hot water. 

Homologues of ethoxyacetylene can be obtained by reaction of the metallated ethynyl ether in liquid ammonia with primary alkyl bromides and iodides 167]. Because of their better solubiliiy, the lithium compounds are preferred over their sodium and potassium analogues, lithium ethoxyacetylide is generated from the readily accessible 2-bromovinyl ethyl ether and two equivalents of lithium amide. This starting compound is obtained as a mixture of the E-and Z-isomer. When this mixture is heated with powdered KOH, only the Z-isomer is converted into ethoxyethyne. Alkali amides are able to conven both isomers into ethoxyethyne and its alkali compounds. A possible explanation for this violation of the "rule of... 

Alkyl azides. Sodium azide as such is of little use for preparation of alkyl azides by nucleophilic substitution reactions because of solubility problems. The reaction can be carried out under phase-transfer conditions with methyltrioctylam-monium chloride/NaN3.3 An even more effective polymeric reagent can be obtained by reaction of NaN3 with Amberlite IR-400.4 This reagent converts alkyl bromides, iodides, or tosylates into azides at 20° in essentially quantitative yield. The solvents of choice are CH3CN, CHC13, ether, or DMF. 

Conversion of phenols into their methyl or ethyl ethers by reaction with the corresponding alkyl sulphates in the presence of aqueous sodium hydroxide affords a method which avoids the use of the more expensive alkyl halides (e.g. the synthesis of methyl 2-naphthyl ether and veratraldehyde, Expt 6.111). Also included in Expt 6.111 is a general procedure for the alkylation of phenols under PTC conditions.38,39 The method is suitable for 2,6-dialkylphenols, naphthols and various functionally substituted phenols. The alkylating agents include dimethyl sulphate, diethyl sulphate, methyl iodide, allyl bromide, epichlorohy-drin, butyl bromide and benzyl chloride. 

Reissert compounds of the type 33 (n = 330,49 and 430) undergo an intramolecular alkylation on treatment with sodium hydride in dimethyl-formamide to give the tricyclic compounds (34). A similar reaction also takes place in the quinoline series.30 When 33 (n = 3) and isopropyl bromide are treated with sodium hydride, cyclization to 34 (n = 3) takes place rather than alkylation with the isopropyl bromide however, treatment of 33(n = 3) and carbon disulfide-methyl iodide with sodium hydride gives 35 rather than cyclization.30 Alkaline peroxide converts the nitrile 34 (n = 3) into an amide, and acid or base hydrolysis gives 4-(l-isoquinolyl)butyric acid.30... 

Reactions. A few of the useful transformations carried out with (1) are formulated. These depend on the fact that (1) is converted into the relatively stable carbanion, CH3SOCHCOOC2H5, by sodium hydride in DMSO at 25°. The carbanion is readily alkylated by primary alkyl bromides or iodides in satisfactory yields. Although (1) is very stable, the alkylated derivatives on heating are converted into a, 3-unsaturated esters. In this way RCH2X can be converted... 

Preparation. Tetraalkylammonium borohydrides can be prepared by addition of a slight excess of sodium borohydride to a solution or suspension of a tetraalkylammonium hydrogen sulfate in an aqueous solution of NaOH. The resulting tetraalkylammonium borohydride is extracted with methylene chloride. The solid salt can be obtained by evaporation of the methylene chloride and crystallization from ethyl acetate. These salts are mild reducing agents. They are converted into diborane and a tetraalkylammonium halide by treatment in methylene chloride with an alkyl halide (methyl iodide, ethyl bromide). The advantage of generation of diborane in this way is that anhydrous methylene chloride is easily obtained. 

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