Synthetic methyl acetone

A product known as synthetic methyl acetone is prepared by mixing acetone (50%), methyl acetate (30%), and methyl alcohol (20%) and is used widely for coagulating latex and in paint removers and lacquers. 

If the small proportion of acetone present in synthetic methyl alcohol is objectionable, it may be removed when present in quantities up to... 

Absolute methyl alcohol. The synthetic methanol now available is suitable for most purposes without purification indeed, some manufacturers claim a purity of 99 85 per cent, with not more than 0 1 per cent, by weight of water and not more than 0 02 per cent, by weight of acetone. Frequently, however, the acetone content may be as high as 0 1 per cent, and the water content 0-5-1 per cent. 

Methyl ketones are important intermediates for the synthesis of methyl alkyl carbinols, annulation reagents, and cyclic compounds. A common synthetic method for the preparation of methyl ketones is the alkylation of acetone derivatives, but the method suffers limitations such as low yields and lack of regioselectivity. Preparation of methyl ketones from olefins and acetylenes using mercury compounds is a better method. For example, hydration of terminal acetylenes using HgSO gives methyl ketones cleanly. Oxymercuration of 1-olefins and subsequent oxidation with chromic oxide is... 

As a symmetrical ketone, acetone is a reactive compound with many synthetic uses. Among the important chemicals based on acetone are methylisobutyl ketone, methyl methacrylate, ketene, and diacetone alcohol. 

Several of the synthetic efforts outlined in Section II were motivated partially by the necessity of increasing the processability of polyanhydrides. Solubilities of the 20 80 copolymers of P(CPP SA) and P(FAD SA) are compared by Domb and Maniar (1993). They reported improved solubility of the later over former in several organic solvents including (in order of decreasing solubility) THF, 2-butanone, 4-methyl-2-pentanone, acetone, and ethyl acetate. 

Pentaerythritol tetranitrate (PETN) is a colorless crystalline solid that is very sensitive to initiation by a primary explosive. It is a powerful secondary explosive that has a great shattering effect. It is used in commercial blasting caps, detonation cords, and boosters. PETN is not used in its pure form because it is too sensitive to friction and impact. It is usually mixed with plasticized nitrocellulose or with synthetic rubbers to form PBXs. The most common form of explosive composition containing PETN is Pentolite, a mixture of 20 to 50% PETN and TNT. PETN can be incorporated into gelatinous industrial explosives. The military has in most cases replaced PETN with RDX because RDX is more thermally stable and has a longer shelf life. PETN is insoluble in water, sparingly soluble in alcohol, ether, and benzene, and soluble in acetone and methyl acetate. 

The ACH process has recently been improved, as stated by Mitsubishi Gas. Acetone-cyanohydrin is first hydrolized to 2-hydroxyisobutylamide with an Mn02 catalyst the amide is then reacted with methylformiate to produce the methyl ester of 2-hydroxyisobutyric acid, with coproduction of formamide (this reaction is catalyzed by Na methoxide). The ester is finally dehydrated with an Na-Y zeolite to methylmethacrylate. Formamide is converted to cyanhydric acid, which is used to produce acetone-cyanohydrin by reaction with acetone. The process is very elegant, since it avoids the coproduction of ammonium bisulphate, and there is no net income of HCN. Problems may derive from the many synthetic steps involved, and from the high energy consumption. 

Photolytic. When synthetic air containing gaseous nitrous acid and 2-methylbutane was exposed to artificial sunlight (X = 300-450 nm), acetone, acetaldehyde, methyl nitrate, peroxy-acetal nitrate, propyl nitrate, and pentyl nitrate were formed (Cox et al, 1980). 

Photolytic. When synthetic air containing gaseous nitrous acid and 4-methyl-2-pentanone was exposed to artificial sunlight k = 300-450 nm), photooxidation products identified were acetone, peroxyacetal nitrate, and methyl nitrate (Cox et al, 1980). In a subsequent experiment, the OH-initiated photooxidation of 4-methyl-2-pentanone in a smog chamber produced acetone (90% yield) and peroxyacetal nitrate (Cox et al, 1981). Irradiation at 3130 A resulted in the formation of acetone, propyldiene, and free radicals (Calvert and Pitts, 1966). 

The bicyclic tropane ring of cocaine of course presented serious synthetic difficulties. In one attempt to find an appropriate substitute for this structural unit, a piperidine was prepared that contained methyl groups at the point of attachment of the deleted ring. Condensation of acetone with ammonia affords the piperidone, 17. Isophorone (15) may well be an intermediate in this process conjugate addition of ammonia would then give the aminoketone, 16. Further aldol reaction followed by ammonolysis would afford the observed product. Hydrogenation of the piperidone (18) followed then by reaction with benzoyl chloride gives the ester, 19. Ethanolysis of the nitrile (20) affords alpha-eucaine (21), an effective, albeit somewhat toxic, local anesthetic. 

The synthetically most useful method for the preparation of dioxiranes is the reaction of appropriate ketones (acetone, trill uoroacetone, 2-butanone, cyclohexanone etc.) with Caroate, commercially available as the triple salt of potassium monoperoxysul-fate (KHSOs). The catalytic cycle of the dioxirane formation and oxidation is shown in Scheme 1 in general form. For acetone as the ketone, by simple distillation at a slightly reduced pressure ca 100 torr) at room temperature ca 20 °C), Jeyaraman and Murray successfully isolated dimethyldioxirane (DMD) as a pale yellow solution in acetone (maximally ca 0.1 M). This pivotal achievement in 1985 fomented the subsequent intensive research activity in dioxirane chemistry, mainly the synthetic applications but also the mechanistic and theoretical aspects. The more reactive (up to a thousandfold ) fluorinated dioxirane, methyl(trifluoromethyl)dioxirane (TFD), was later isolated in a similar manner by Curd, Mello and coworkers". For dioxirane derived from less volatile ketones, e.g. cyclohexanone, the salting-out technique has been developed by Murray and coworkers to obtain the corresponding dioxirane solution. 

Figure 1. Separation of selected solvents spiked into a synthetic sample at TLV levels (A) aqueous phase, (B) carbon disulfide phase 1, ethanol, 2, acetone, 3, carbon disulfide, 4, 2-propanol, 5, 1-propanol, 6, methyl ethyl ketone, 7, ethyl acetate, 8, 1-butanol, 9, isopropyl acetate, 10, n-hexane, 11, n-propyl acetate, 12, methyl isobutyl ketone, 13, toluene (19)...

The largest offtake of acetone is its conversion into solvents, used mainly in lacquers and other synthetic resin applications. These solvents include diacetone alcohol, methyl isobutyl ketone, methyl isobutyl carbinol (methyl amyl alcohol), and methyl amyl acetate. The following equations (22), in each of which the raw material is the product of the previous reaction, show a possible procedure by which these solvents may be made ... 

Treatment of a 5-methoxy-2-furyl carbinol (106) with zinc chloride in acetone-water converts it into two products, the 4-ylidenebutenolide (111) and the 4-oxo-2-enoic acid methyl ester (112) in approximately 3 1 ratio (80T3071). The key step in this conversion is the formation of carbonium ion (107) which subsequently adds water to furnish (108). Intermediate (108) is in prototropic equilibrium between (109) and (110). The latter then break down to furnish the final products (Scheme 26). The overall scheme provides a new synthetic route to the 4-ylidenebutenolides, a class of compound that includes many natural substances of biological importance. 

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