Acetone from propyne

To a solution of ethylnagnesium bromide in 350 ml of THF, prepared from 0.5 mol of ethyl bromide (see Chapter 11, Exp. 6) was added in 10 min at 10°C 0.47 mol of 1-hexyne (Exp. 62) and at 0°C 0.47 mol of trimethylsilylacetylene (Exp. 31) or a solution of 0.60 mol of propyne in 70 ml of THF (cooled below -20°C). With trimethyl si lylacetylene an exothermic reaction started almost immediately, so that efficient cooling in a bath of dry-ice and acetone was necessary in order to keep the temperature between 10 and 15°C. When the exothermic reaction had subsided, the mixture was warmed to 20°C and was kept at that temperature for 1 h. With 1-hexyne the cooling bath was removed directly after the addition and the temperature was allowed to rise to 40-45°C and was maintained at that level for 1 h. 

We have also observed competition between products resulting from C-C and C-H bond activation in reactions of Y with propene,138 propyne,143 2-butyric,143 four butene isomers,138 acetaldehyde,128 acetone,128 ketene,144 and two cyclohexadiene isomers,145 as well as for Zr, Nb, Mo, and Mo with 2-butyne.143 In this chapter, we use the term C-C activation to describe any reaction leading to C-C bond fission in which the hydrocarbon reactant is broken into two smaller hydrocarbon products, with one hydrocarbon bound to the metal. It is important to note, however, that C-C activation does not necessarily require true C-C insertion. As will be shown in this chapter, the reaction of Y, the simplest second-row transition metal atom, with propene leads to formation of YCH2 +C2H4. The mechanism involves addition to the C=C bond followed by H atom migration and C-C bond fission, rather than by true C-C insertion. 

The catalytic propargylic alkylation was investigated in the presence of thiolate-bridged diruthenium complexes as catalysts generated in situ from reactions of [Cp RuCl(p2-Cl)]2 with optically active thiols prepared from the corresponding optically active alcohols [27]. Typical results for the reaction of 1-phenyl-2-propyn-l-ol with acetone in the presence of a variety of catalysts are shovm in Scheme 7.19. 

Acetone dibutyl acetal has been prepared from isopropenyl acetate and butanol, from butanol and isopropenyl butyl ether obtained from the reaction of butanol with propyne, and by orthoformic ester synthesis. ... 

Bos and coworkers have developed several applications of alkyne-ketone photoadditions to organic synthesis. 2 Irradiation of a solution of acetone and 1-methylthio-l-propyne gives as a major product the cycloadduct (67) this results from selective oxetane formation due to radical stabilization by the methyl-thio group, followed by electrocyclic ring opening. Similarly, photoreaction of benzil and 1-t-butylthio-1-propyne gave the adduct (68) in 45% yield, which was transformed in 90% yield to the furan (69). 

The exact mechanism of propylene glow discharge polymerization is not known. The presence of a terminal acetylene (presumable propyne) in the gaseous products of propylene polymerization was indicated by the interaction of the cold trap gaseous condensates with 1% alcoholic or ammonlacal AgNO sol.(22) after the polymerization was over. An immediate formation of an explosive silver acetyllde was detected. Intermediate formation of propyne is also indicated by the IR spectra of the yellow relatively less volatile liquid left in the cold trap after the polymerization was over. Sharp but weak absorptions at 3310 cm l and 1270 cm are indications of a substituted acetylenic compound. The IR spectra of the yellow liquid also points to the presence of mono, dl- and trl-substituted aromatic compounds in the mixture (i.e. sharp absorption bands at 3080 cm l, 1640 cm l, 920 cm , 810 cm and a multiple band in the 1000-1120 cm l region are observed). The NMR spectra in deuterated acetone indicated the presence of an aromatic nucleus in the yellow liquid obtained from the cold trap. The formation of aromatic compounds can be explained if a propynyllc Intermediate is involved. 

Ethylenic and acetylenic alcohols can be converted into ketones or aldehydes by a mild reaction at room temperature, which consists of shaking them in an inert solvent such as petrol, chloroform, benzene, or acetone with a synthetic Mn02 H20.446 The reaction is highly recommended for oxidation of hydroxyl groups in sensitive compounds l-phenyl-2-propyn-l-one is thus obtained in 67.6% yield from l-phenyl-2-propyn-l-ol.447... 

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