Methyl halides, hydrolysis

Methylsuccinic acid has been prepared by the pyrolysis of tartaric acid from 1,2-dibromopropane or allyl halides by the action of potassium cyanide followed by hydrolysis by reduction of itaconic, citraconic, and mesaconic acids by hydrolysis of ketovalerolactonecarboxylic acid by decarboxylation of 1,1,2-propane tricarboxylic acid by oxidation of /3-methylcyclo-hexanone by fusion of gamboge with alkali by hydrog. nation and condensation of sodium lactate over nickel oxide from acetoacetic ester by successive alkylation with a methyl halide and a monohaloacetic ester by hydrolysis of oi-methyl-o -oxalosuccinic ester or a-methyl-a -acetosuccinic ester by action of hot, concentrated potassium hydroxide upon methyl-succinaldehyde dioxime from the ammonium salt of a-methyl-butyric acid by oxidation with. hydrogen peroxide from /9-methyllevulinic acid by oxidation with dilute nitric acid or hypobromite from /J-methyladipic acid and from the decomposition products of glyceric acid and pyruvic acid. The method described above is a modification of that of Higginbotham and Lapworth. ... 

The formation of ethyl cyano(pentafluorophenyl)acetate illustrates the intermolecular nucleophilic displacement of fluoride ion from an aromatic ring by a stabilized carbanion. The reaction proceeds readily as a result of the activation imparted by the electron-withdrawing fluorine atoms. The selective hydrolysis of a cyano ester to a nitrile has been described. (Pentafluorophenyl)acetonitrile has also been prepared by cyanide displacement on (pentafluorophenyl)methyl halides. However, this direct displacement is always aecompanied by an undesirable side reaetion to yield 15-20% of 2,3-bis(pentafluoro-phenyl)propionitrile. 

The Mobil process as discussed still uses syngas in its initial step. Olah has shown,79 however, that it is possible to convert methane directly by selective electrophilic halogenation to methyl halides and through their hydrolysis to methyl alcohol [Eq. (1.12)]. When bromine is used, the HBr byproduct of the reaction is readily reoxidized to bromine, allowing a catalytic process in which bromine acts only as a redox catalyst [Eq. (1.13)] ... 

Swain and Scott56 have measured the knC lkHF ratio in neutral or slightly acidic solutions for the hydrolysis of acetyl and benzoyl halides and compared them with those for triphenylmethyl halides. Values for the triphenyl-methyl halides are — 104 greater than those for acyl halides (Table 10) reflecting the tendency for C-X bond breaking to be more complete than O-C formation at the transition state of trityl hydrolysis and the opposite tendency with the benzoyl halides. The C-F bond is harder to break but the carbon atom is made more electropositive. 

We start by considering the hydrolysis of methyl halides since it is for this... 

Fig. 24 Evidence for the transition states in the hydrolysis of methyl halides from the different probes Marcus analysis, a 0.5 charge development, Z. Vi = 0.70, JZ, rjY = 0.46 solvent isotope effect, dotted lines (see Fig. 13) o-deuterium isotope effect, r 1.0 Hammett relations, shaded area (see Fig. 23)...

Fig. 27 Map of the transition states. The transition states are located as follows A, hydrolysis of methyl halides B, isopropyl transition states C, hydrolysis of t butyl chloride (or at D in Fig. 3) M, Menschutkin reactions...

Returning to the hydrolysis of methyl halides, we recognize that the deduction of structure from the deuterium isotope effect is sensitive to the choice at r = 1. If instead of (109) we write (128), then for the hydrolysis of methyl bromide we can calculate the values of r for different values of A. The... 

Indeed, this behaviour is observed for the hydrolysis of methyl halides, e.g., for MeCl, ACp = —205 J mol-1 K-1 (Robertson, 1967) and Cp3 = +180 J mol-1 K-1 (Glew and Moelwyn-Hughes, 1953). This close agreement and the general observation that, for hydrolysis of this class of solutes, ACp < 0 prompted the proposal that activation in hydrolysis required the breakdown of water-water interaction in the neighbourhood of the solute. 

The hydrolysis of methyl fluoride in water (Glew and Moelwyn-Hughes, 1952) requires more negative values of AO and AS than that of the other methyl halides (see also Chapman and Levy, 1952) but the comparison requires extrapolation over a large temperature interval and may therefore not be reliable (see SectionIIB2). The reactions of methyl nitrate (McKinley-McKee and Moelwyn-Hughes, 1952) and dialkyl sulphates (Robertson, 1966) with water show values of AG and AS which are similar to those found in the Su2 solvolysis of halides. 

Although Forster initially reported this reaction, it was Decker and Becker who investigated it in more depth and made this reaction an applicable route for the preparation of secondary amines. Therefore, this reaction is known as the Decker-Becker method or Forster reaction, but it is named the Decker-Becker secondary amine synthesis in this book. It is the synthesis of secondary amine by the condensation of primary amines with aldehydes to form an imine intermediate, which then reacts with alkyl halides via alkylation to Anally afford secondary amines after hydrolysis. This reacAon gives good results when methyl halides are used but works poorly and unstably when larger alkyl halides are applied. ... 

They also found that solid acid catalysts, such as Nafion-H, are also capable of catalyzing the hydrolysis of methyl halides and yielding dimethyl ether under the reaction temperatures of 150-170 °C (equation... 

Lau and Schollkopf 184) prepared a-mono- or disubstituted nitrone esters (195) (Scheme 42) by metalation of (191) with potassium / r/-butylate in THF and subsequent alkylation using alkyl halides. Hydrolysis of (195) then furnishes a,a-disubstituted N-hydroxyamino acids (67,196) and their methyl esters (76). 

Table 4.22 Hydrolysis of methyl halides over 7-alumina...

Most of the alkylations were carried out by adding a solution of 3,3-ethylenedioxypregna-5,16-dien-20-one in tetrahydrofuran to a solution of lithium in liquid ammonia to the point of color discharge. Treatment with the alkyl halide then furnishes the corresponding 17a-alkyl derivative (10). After hydrolysis of the 3-ketal group, 17a-methyl-, ethyl-, propyl-, butyl-, hexyl-, octyl-, allyl-, and benzylprogesterones are obtained. 

Electrochemical reduction of oxazolinium salts 36 gives the anions 37, which add efficiently to alkyl halides or, in the presence of McsSiCl, to methyl acrylate, methyl vinyl ketone, and acrylonitrile. Simple acid hydrolysis then gives the ketone products 38 and 39, and this method is quite general since the starting salts are readily prepared from carboxylic acids, R C02H (87TL4411). 

Acetoacetic ester synthesis (Section 22.7) The synthesis of a methyl ketone by alkylation of an alkyl halide, followed by hydrolysis and decarboxylation. 

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