Neopentyl alcohol, alkylation with

Alkyl sulfates, tosylates, and other esters of sulfuric and sulfonic acids can be converted to alkyl halides with any of the four halide ions.979 Neopentyl tosylate reacts with Cl, Br, or I without rearrangement in HMPA.980 Similarly, allylic tosylates can be converted to chlorides without allylic rearrangement by reaction with LiCl in the same solvent.981 Inorganic esters are intermediates in the conversion of alcohols to alkyl halides with SOCl2, PC15, PC13, etc. (0-67), but are seldom isolated. 

The effect of catalysts on product distribution is shown in case of alkylation of benzene with neopentyl alcohol 194195... 

Alkyl cyanates. Kauer and Henderson found that an alcohol such as neopentyl alcohol can be converted into the corresponding cyanate, if in low yield, by successive treatment with sodium hydride and cyanogen chloride. 1,4-Dihydroxybicyclo-[2.2.2]octane afforded the dicyanate, m.p. 155-156 , in reasonable yield. The... 

Direct preparation of an alkyl iodide by reaction (a) neopentyl iodide, (CH3)3CCH2I 957,958 Methyl iodide (1.4 moles), triphenyl phosphite (1 mole), and neopentyl alcohol (1 mole) are heated in a bath for 24 h, whereby, owing to continuing consumption of methyl iodide, the internal temperature rises from 75° to 130°. The crude iodide and the phenol are distilled off in a vacuum and the distillate is washed with ice-cold, dilute NaOH solution, and water until free from phenol. The product contains about 6% of te/7-pentyl iodide,958 to remove which it is shaken for 5 h with three times its volume of water which is then discarded. The organic layer is next shaken with its own volume of O.lN-aqueous AgN03, washed with water, dried, and fractionated. This gives a 53-57% yield of iodide of b.p. 71°/100 mm. 

Alkyl chlorides.Alcohols react with hydrogen chloride in HMPT at 50-85° to form alkyl chlorides in 65-90% yield. The reaction of primary alcohols is rapid (30 min.) longer reaction times are required for secondary and tertiary alcohols (about 1 hr.). Neopentyl alcohol reacts without formation of rearranged products. Racemic product was obtained from 2-octanol. 

The mechanism and kinetics of the sulfation of the lower alcohols with sulfuric acid have been studied. The reaction proceeds by a bimolecular displacement mechanism like that of the acid-catalyzed esterification of alcohols with carboxylic acids no oxygen-alkyl fission occurs. Neopentyl alcohol sulfates at a rate comparable to other secondary alcohols these results indicate that within the groups of primary and secondary alcohols steric effects are minor. However, primary alcohols sulfate at a rate ten times that of secondary alcohols. The experimentally determined rate law... 

Sulfuric acid reacts with primary and secondary alcohols by a bimo-lecular displacement reaction with no alkyl-oxygen fission. The mechanism of the reaction is similar to the acid-catalyzed esterification of carboxylic acids. Sulfation of optically active 2-butanol gives a sulfate ester with complete retention of configuration. In addition, neopentyl alcohol sulfates without rearrangement. 

Reaction of tris(neopentyl) complexes of titanium, zirconium and hafnium with molecular oxygen furnishes the corresponding tris(neopentoxy) complexes [42, 43, 51]. A peroxo complex is an intermediate in this reaction, being relatively stable in the case of titanium [42]. The alkoxide species can also be formed upon reaction with alcohols under mild conditions [42, 52]. The alcoholysis reaction is fast, with a low dependence on the steric hindrance of the alkyl chain [42]. Hydrolysis leads to ](=SiO)M(OH)3] or ](=SiO)2M(OH)2], depending on the precursor species. Deu-... 

Thioethers (sulfides) can be prepared by treatment of alkyl halides with salts of thiols (thiolate ions).7S2 R may be alkyl or aryl. As in 0-35, RX cannot be a tertiary halide, and sulfuric and sulfonic esters can be used instead of halides. As in the Williamson reaction (0-12), yields are improved by phase-transfer catalysis.753 Instead of RS ions, thiols themselves can be used, if the reaction is run in benzene in the presence of DBU (p. 1023).754 Neopentyl bromide was converted to Me3CCH2SPh in good yield by treatment with PhS in liquid NH3 at -33°C under the influence of light.755 This probably takes place by an SrnI mechanism (see p. 648). Vinylic sulfides can be prepared by treating vinylic bromides with PhS in the presence of a nickel complex,756 and with R3SnPh in the presence of Pd(PPh3)4.757 R can be tertiary if an alcohol is the substrate, e.g,758... 

The nucleophilic displacement of halogens by fluorine can be successfully carried out by reaction with potassium fluoride under several conditions. Primary and secondary alkyl halides 1 are converted to the corresponding fluorides 2 by heating with a saturated aqueous solution of potassium fluoride in the presence of catalytic amounts of hexadecyltributylphosphonium bromide.56 Small amounts of the corresponding alcohol and the olefinic elimination product are formed as side products. While neopentyl bromide does not react at all, polyhaloalkanes give only products of elimination or hydrolysis. Chlorocyclohexane gives only the elimination product.56... 

The above-mentioned reactions for the introduction of bromine always involve an activation of the alcohol as the first step. In some cases it can be useful to isolate the activated intermediate. The reactions of alkyl mesylates or tosylates with MgBr2 give alkyl bromides under mild conditions with good yields (equation 20) Neopentyl tosylate with LiBr in HMPA gives neopentyl bromide in 67% yield (equation 21). Complete inversion with little or no rearrangement is observed in this difficult case. 

Displacements. Primary and secondary alkyl chlorides react rapidly and exother-mally with sodium cyanide in partial solution in dimethyl sulfoxide to give the corresponding nitriles in excellent yield. - The reactions are faster and the yields better than in the reactions of the corresponding bromides or iodides in aqueous alcohol. Neopentyl and neophyl halides can be converted by this method to... 

Michaelis and Kaehne isolated a product with saltlike properties from the reaction of triphenyl phosphite and methyl iodide. This observation has been confirmed by Arbuzov and Sazonova (30) and by Landauer and Rydon (206,284), who used this salt as a reagent for the preparation, in excellent yields, of alkyl halides, including neopentyl iodide, from the corresponding alcohols. The course of this reaction... 

Following a comparison of the behaviours of trialkyl phosphites, mixed alkyl phenyl phosphites and triphenyl phosphite towards iodomethane and, in the last case, the breakdown of the phosphonium salt when treated with an alcohol, Landauer and Rydon considered that all the reactions involve a stage identical with that of the normal Michaelis-Arbuzov reaction. The absence of any rearrangement during the decomposition of complexes from neopentyl phosphites, and the configurational inversion which occurs when optically active 2-halooctanes are produced from optically active phosphite triesters (themselves obtained from optically active octan-2-ol), suggest that the mode of breakdown of the intermediate complexes is of S 2 character. 

Alkyl radicals are oxidized by ion-oxidants to olefins and alcohols or esters. In many cases, carbocations are formed as intermediates, which proves the composition of the oxidation products. The oxidation of the neopentyl radical with copper acetate in acetic acid results in the formation of isomeric 2-methylbutenes and /ert-amyl acetate, which agrees with reactions involving intermediate carbocations... 

Photosensitized oxidation of ethers causes a-deprotonation in the case of methyl neopentyl ether, CC and CH fragmentation compete. The resulting radicals react with the sensitizer, viz. an aromatic nitrile or an iminium salt. As in the case of amines, a-trimethylsilyl ethers and thioethers are excellent precursors for the corresponding a-heteroatom-substituted alkyl radicals.The potassium salts of a-oxoalkyl and a-thioalkyl carboxylic acid decarboxylate upon photosensitization by phthahm-ides. Alcohols undergo, as expected, a-CH and no OH deprotonation, via the radical cation formed with sensitizers such as tetracyanobenzene (see Equation 4.24) and pyrrohnium salts. ... 

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