Low boiling ketone

The most commonly used protected derivatives of aldehydes and ketones are 1,3-dioxolanes and 1,3-oxathiolanes. They are obtained from the carbonyl compounds and 1,2-ethanediol or 2-mercaptoethanol, respectively, in aprotic solvents and in the presence of catalysts, e.g. BF, (L.F. Fieser, 1954 G.E. Wilson, Jr., 1968), and water scavengers, e.g. orthoesters (P. Doyle. 1965). Acid-catalyzed exchange dioxolanation with dioxolanes of low boiling ketones, e.g. acetone, which are distilled during the reaction, can also be applied (H. J. Dauben, Jr., 1954). Selective monoketalization of diketones is often used with good success (C. Mercier, 1973). Even from diketones with two keto groups of very similar reactivity monoketals may be obtained by repeated acid-catalyzed equilibration (W.S. Johnson, 1962 A.G. Hortmann, 1969). Most aldehydes are easily converted into acetals. The ketalization of ketones is more difficult for sterical reasons and often requires long reaction times at elevated temperatures. a, -Unsaturated ketones react more slowly than saturated ketones. 2-Mercaptoethanol is more reactive than 1,2-ethanediol (J. Romo, 1951 C. Djerassi, 1952 G.E. Wilson, Jr., 1968). 

Reduced pressure should not be used when low-boiling ketones are reduced and only a small excess of aluminum isopropoxide is used, since some of the product may be liberated from its aluminum derivative and lost through an exchange with the exoess isopropyl alcohol. 

In general, the yields in aluminum isopropoxide reductions range from 80 to 100%. With a few low-boiling ketones difficulty may be experienced in separating the resulting alcohol from isopropyl alcohol thus the yields of reduction products from diethyl ketone and methoxyacetone are reported to be 60% and 40%, respectively. Di-n-propyl ketone, on the other hand, gives a 92% yield of the carbinol. As would be expected, side reactions are more significant and the yields are consequently lower when extremely sensitive compounds, such as unsaturated aldehydes and the carotenoids, are reduced. 

Diethylene glycol dimethyl ether ( diglyme, bp 161°) is an excellent water-miscible solvent. It is, for example, one of the few solvents other than water in which sodium borohydride is reasonably soluble. Its high boiling point is often a convenience for example, a low-boiling ketone or aldehyde may be reduced in this solvent by lithium aluminum hydride, a high-boiling alcohol (such as butyl... 

Solvents used for paint removal are able to dissolve or considerably swell physically drying binders (e.g., vinyl chloride copolymers, cellulose nitrate, polyacrylates) and chemically cross-linked coatings (e.g., oil-based paints, dried alkyd resins, cross-linked polyester-melamine resins, cross-linked epoxy and isocyanate coatings) [14.237]. A combination of dichloromethane with low-boiling ketones or esters is particularly suitable. Small amounts of high-boiling solvents with a low volatility (e.g., tetrahydronaphthalene, solvent naphtha, methyl benzyl alcohol, or benzyl alcohol) are added to these mixtures to retard evaporation and increase the solvency. Modern paint removers do not contain chlorinated hydrocarbons, they are formulated on the basis of high boilers (e.g., dimethylformamide, dimethyl sulfoxide, propylene carbonate, and yV-methylpyrrolidone) in combination with alcohols and aromatics, or consist of aqueous, frequently alkaline or acidic systems. 

Low boiling solvents like alcohols or low boiling ketones may be added to lower the surface tension of the PEDTPSS dispersion, thereby increasing the wetting of substrates. These additives... 

Acetone a-so- ton [Gr Azeton, fr. L acetum] (1839) (dimethyl ketone, 2-propanone) n. CH3COCH3. The simplest and most important member of the ketone family of solvents. All the cellulosics plastics and polyvinyl chloride, polyvinyl acetate, polymethyl methacrylate, epoxies, and some thermosetting resins are soluble in acetone. It is also an intermediate in the production of bisphenol. It is a typical low-boiling ketone. It is a liquid which flashes at ordinary room temperature, has a bp of 57.5°C, fp of-15°C and a Sp gr of 0.788 at 25°C. Ash M, Ash I (1996) Handbook of paint and coating raw materials trade name products - Chemical products dictionary with trade name cross-references. Ashgate Publishing Ltd., New York Weast RC Handbook of chemistry and physics. The Chemical Rubber Co., Boca Roton, FL. 

In typical processes, the gaseous effluent from the second-stage oxidation is cooled and fed to an absorber to isolate the MAA as a 20—40% aqueous solution. The MAA may then be concentrated by extraction into a suitable organic solvent such as butyl acetate, toluene, or dibutyl ketone. Azeotropic dehydration and solvent recovery, followed by fractional distillation, is used to obtain the pure product. Water, solvent, and low boiling by-products are removed in a first-stage column. The column bottoms are then fed to a second column where MAA is taken overhead. Esterification to MMA or other esters is readily achieved using acid catalysis. 

There are several side reactions which reduce the yield. There are always unchanged ketone and ester in the low-boiling fraction, and also some chlorocinnamic ester. 

The number average molecular weight of the PMMA sample was 24,000, and the amount of butyl lsopropenyl ketone unit in this polymer could be calculated to be 0.42mol% of MMA unit if a polymer molecule was assumed to contain one ketone unit. The amount of the ketone formed in the depolymerization reaction was 0.3mol% of MMA formed and corresponded to about 70% of the theoretical value. The depolymerization of the oligomer also gave low-boiling products in 53% yield, which contained about 9% of butyl lsopropenyl ketone. 

The fluorination of nitriles is successful only if the resulting trifluoromethyl derivatives are low-boiling compounds (bp < IOC). Butyronitrile and isobutyronitrile give a mixture of products. The same trend is observed in the fluorination of ketones. Acetone is converted into 2,2-difluoropropane (90%) but other ketones, such as ethyl methyl ketone, undergo fragmentation.126... 

Imines. Imines are usually prepared by acid-catalyzed condensation of aldehydes or ketones with primary amines with azeotropic removal of water. This method gives poor yields with low-boiling imines.2 A new method involves dehydrocyanation of a-cyanoamines with DCC and Dabco as catalyst (equation I).3... 

Turmeric owes its aromatic taste and smell to the oil present in the rhizome. Analysis of the oil, obtained by steam distillation of the powdered rhizome, followed by fractional distillation and derivatization, shows that the components are a mixture of predominantly sesquiterpene ketones and alcohols (Kelkar and Rao, 1933). The residue on steam distillation yields mainly sesquiterpene alcohols. Besides these major components, they have also identified a mixture of low-boiling terpenes, c/-sabinene, a-phellandrene, cineole, borneol and the higher-boiling sesquiterpene, zingiberene, in substantial amounts (25%). 

Simple distillation cannot separate aromatics from noD -aromatic, because the relative volatilities are very low, and many azeotropes are formed. Azeotropic distillation is based on the formation of an azeotrope betu een the non-aromatic hydrocarbons and a low boiling polar solveat It is select among the hrst terms of the series of alcohols, ketones, aldehydes and nitriles, and is employed pure or mixed with water. If the solvent forms a hetero-azeotrope, its recovery is accordbgly facilitated. The )aeld is not limited in principle. The impurity content of the feedstock and the composition of the azeotrope determine the amount of solvent required. Cuts rich in aromatics can be treated in this way fairly economically. However, any variation in the type of impurity to be removed, and consequently in the composition of the azeotrope, may lead to less perfect purification. Furthermore, this method can be applied only to a narrow cut which contains... 

The isolation of the major volatile compounds, i.e. low boiling point alcohols, and their relative aldehydes, Z ketones and one major sulfur compound was consistent with previous reports (2,3) Although alcohols remained the major constituents of headspace volatiles, dimethyl sulfide was present in greater proportion than in our earlier studies. 

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