Reaction with methanol

With aldehydes, primary alcohols readily form acetals, RCH(OR )2. Acetone also forms acetals (often called ketals), (CH2)2C(OR)2, in an exothermic reaction, but the equiUbrium concentration is small at ambient temperature. However, the methyl acetal of acetone, 2,2-dimethoxypropane [77-76-9] was once made commercially by reaction with methanol at low temperature for use as a gasoline additive (5). Isopropenyl methyl ether [116-11-OJ, useful as a hydroxyl blocking agent in urethane and epoxy polymer chemistry (6), is obtained in good yield by thermal pyrolysis of 2,2-dimethoxypropane. With other primary, secondary, and tertiary alcohols, the equiUbrium is progressively less favorable to the formation of ketals, in that order. However, acetals of acetone with other primary and secondary alcohols, and of other ketones, can be made from 2,2-dimethoxypropane by transacetalation procedures (7,8). Because they hydroly2e extensively, ketals of primary and especially secondary alcohols are effective water scavengers. 

The / f/-butanol (TBA) coproduct is purified for further use as a gasoline additive. Upon reaction with methanol, methyl tert-huty ether (MTBE) is produced. Alternatively the TBA is dehydrated to isobutylene which is further hydrogenated to isobutane for recycle ia the propylene oxide process. 

The dimethyl acetal (94) is readily prepared from the 22-aldehyde (93) by direct reaction with methanol in the presence of hydrogen chloride. Ena-mines (95) are formed without a catalyst even with the poorly reactive piperidine and morpholine.Enol acetates (96) are prepared by refluxing with acetic anhydride-sodium acetate or by exchange with isopropenyl acetate in pyridine.Reaction with acetic anhydride catalyzed by boron trifluoride-etherate or perchloric acid gives the aldehyde diacetate. 

Allylic A" -3-hydroxyls are particularly reactive, although some difficulty arises because this system is prone to acid-catalysed dehydration to the 3,5-diene. A" -3-Methyl ethers are readily prepared by direct, p-toluenesulfonic acid-catalysed reaction with methanol. 

The oxazolone 43, prepared by reaction of 0-methylcaprolactim (42) with compound 1, undergoes a ring-opening reaction with methanolic HCl and cyclizes in alkaline medium to 1,5-pentamethyl-ene-2-phenylimidazole-4-carboxylic acid (44), which can be decar-boxylated easily. 

Methylamines can be synthesized by alkylating ammonia with methyl halides or with methyl alcohol. The reaction with methanol usually occurs at approximately 500°C and 20 atmospheres in the presence of an... 

The intermediate o-bromo acid bromide undergoes a nucleophilic acyl substitution reaction with methanol to give an a-bromo ester. 

Similarly, 17/-1,4-benzodiazepinc-2,5(3//,4//)-dione (3) is cleaved to 2-aminobenzoic acid by hot 70% sulfuric acid the reaction with methanolic methylamine provides /V-methyl-o-aminohippuramide.209... 

Organoaluminium derivatives with the formuia RxAIZ3 x (Z = OR, OH, X) give rise to explosive reactions with methanol and ethanol. With very strong bases, the reaction can be written down as ... 

The formation of 151 from the phosphonate 171 could be proved only by indirect means. Electron-rich aromatic compounds such as N,N-diethylaniline and N,N,N, N -tetraethyl-m-phenylenediamine U0 1I9> and N-methylaniline 120> are phosphorylated in the para- and in the ortho- plus para-positions by 151. Furthermore, 151 also adds to the nitrogen lone pair of aniline to form the corresponding phosphor-amidate. Considerable competition between nucleophiles of various strengths for the monomeric methyl metaphosphate 151 — e.g. aromatic substitution of N,N-diethylaniline and reaction with methanol or aromatic substitution and reaction with the nitrogen lone pair in N-methylaniline — again underline its extraordinary non-selectivity. 

Reaction with methanol may be vigorously exothermic. A mixture of bromine (9 ml) and methanol (15 ml) boiled in 2 m and in a previous incident such a mixture had erupted from a measuring cylinder [1], The exotherm with industrial methylated spirits (ethanol containing 5% methanol) is much greater, and addition of 10 ml of bromine to 40 ml of IMS rapidly causes violent boiling [2], A further case of ejection of a methanol solution of bromine from a measuring cylinder was described [3],... 

The nC-methyl iodide co-reaction with methanol was also carried out to follow the... 

These compounds are thermally stable, but sensitive to oxidation. The boron atom is not very reactive, due to conjugation of its vacant orbital with the nitrogen lone electron pair, resulting in the absence of intermolec-ular coordination. However, these compounds undergo reactions with methanol, giving methoxy derivatives (172). The latter interact with lithium alkylides, and form, depending on their nature, borates (173) or 13-alkyl derivatives (174) [Eq. (131)]. 

Isomerization of betaines 20k, 1 to silylated phosphorus ylides was also confirmed by their reaction with methanol-Ji, which occurs rather rapidly at room temperature to give Me2Si(OMe)2 and mixtures of a-deuterated phosphonium salts 72k, 1 (Scheme 33). It is most probable that, in this case, the reaction occurs mainly through the intermediate formation of a-silylated... 

The compound 86 in which R = /-Pr and R = R" = Me181 decomposes and rearranges intramolecularly to product 89 which, upon reaction with methanol, gives 90. In the same way182, the reaction of bis(trimethylsilylethynyl)dimethyllead 91 with trialkylb-oranes gives 3-(dialkylboryl)-4-alkyl-2,5-bis(trimethylsilyl)-l,l-dimethylplumbole 93 via the intermediate 92 (Scheme 22b) ... 

In accordance with the different stabilities of 25, 26, and 33 toward hydrolytic, lactone ring-opening, on reaction with methanol catalyzed by weak bases, compounds 26, 33, and 25, in that order, afford110 decreasing proportions of the corresponding methyl D-glucofuranuronate derivatives 63, 64, and 65. All of these compounds... 

Moreover, one should mention that in spite of similar electronic structures, PBN and the isoquinoline nitrone (278) react in a different way. Under no circumstances does PBN give an oxidative methoxylation product, whereas nitrone (278) reacts readily to form a,a-dialkoxy-substituted nitroxyl radical (280) (517). Perhaps this difference might be due to the ability to form a complex with methanol in aldo-nitrones with -configuration. This seems favorable for a fast nucleophilic addition of methanol to the radical cation (RC), formed in the oxidation step. The a-methoxy nitrone (279), obtained in the initial methoxylation, has a lower oxidation potential than the initial aldo-nitrone (see Section 2.4). Its oxidation to the radical cation and subsequent reaction with methanol results in the formation of the a,a-dimethoxy-substituted nitroxyl radical (280) (Scheme 2.105). 

Adapted from Srivatsava et al. (248). Reaction conditions for reactions with methanol (3.2 g)— catalyst (TiMCM-41 Si/Ti = 46), 400 mg cyclic carbonate, 1.36 g temperature, 393 K, reaction time = 2 h. For reactions with phenol (4.7 g) reaction time = 17 h and rest all are the same. a Balance is phenyl ether. 

Nearly quantitative generation of l,3-bis(methylthio)allyllithium was proved, as this solution yielded l,3-bis(methyIthio)propene (88-89%) and l,3-bis(methylthio)-l-butene (89%) by reaction with methanol and methyl iodide, respectively. The checkers found that lithium diisopropylamide can be replaced by w-butyllithium without any trouble for the generation of l,3-bis(methylthio)allyllithium, simplifying the procedure considerably at least in this particular case. Subsequent reaction with propionaldehyde gave l,3-bis(methylthio)-l-hexen-4-ol in 85% yield, and no appreciable amount of by-product, such as the addition product of w-hutyllithium with propionaldehyde or with the intermediate 1.3-bis(methylthio)propene, was formed. 

Palladium(O) forms a complex with quinone that is now electron rich and can be protonated to give hydroquinone and palladium(II). The latter can start a new cycle via a carbomethoxy species after reaction with methanol and CO (c.f. reaction (6), Figure 12.4). Thus we have formally switched from a hydride initiator to a carbomethoxy initiator species. Addition of quinone to a nonactive or moderately active palladium system is a diagnostic tool that tells us whether zerovalent palladium is involved as an inactive state. Likewise, one might add dihydrogen to a system to see whether palladium(II) salts need to be converted to a hydride to reactivate our dormant catalyst. 

The large change of shapes of the base line and the very large negative peak around 1600 cm are due to the decrease in the amount of water between the window and the electrode. The decrease in water seemed to be caused partly by the reaction with methanol, but mainly by CO2 gas evolution because between the window and the electrode, there is not enou solution to dissolve all the CO2 formed on the electrode. Indeed, gas bubbles were seen in these high concentration methanol experiments, which were not foimd in 0.1 M methanol experiments. 

The silanol groups which had not been esterified on reaction with methanol did still react with thionyl chloride. Gok9ek (231) found that the sum of methoxy content (after reaction with methanol vapor at various temperatures) and chloride formation remained nearly constant. 

Isobutylene is the most chemically reactive of the butylene isopiers. If the objective is just to get the isobutylene out of the C4 stream, it can be removed by reaction with methanol (CH3OH) to make MTBE (methyl tertiary butyl ether), by reaction with water to make TBA (tertiary butyl alcohol), by polymerization, or by solvent extraction. After that, butene-1 can be removed by selective adsorption or by distillation. That leaves the butene-2 components, together with iso- and normal butane, which are generally used as feed to an alkylation plant. 

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