Unsaturated compounds alcohol reactions with halides

In addition to allylic alcohols, other unsaturated alcohols react with halides to give carbonyl compounds. Although the reaction was slow (three days), the reaction of 10-undecen-l-ol (50) with iodobenzene afforded the aldehyde 52 in a high yield. In this... 

The Sn2 mechanism is ruled out for reaction between the tertiary halide, r-BuBr, and radical anions derived from the more easialy reduced compounds cinnamonitrile (9) ethyl cinnamate (12a), methyl styryl ketone (23a), and phenyl styryl ketone (20a). Reduction of the activated alkenes in the presence of an excess of r-BuBr leads to mixtures of products where a r-Bu group has been introduced in a- or j0-position or in the phenyl ring. For 9 and 12a small amounts of butylated hydrodimers were obtained in addition, and for the enone 23a formation of the unsaturated alcohol with introduction of the /-Bu group at C-1 was a major product [192]. In this case the mechanism is unambiguously reduction of the activated alkene followed by electron transfer to r-BuBr concerted with halide cleavage, in... 

Nitropropene (Scheme 14) undergoes a,a-double-deprotonation to give a dianion that reacts with carbonyl compounds at the a-nitro carbon to form nitro alcohols, whereas 4-nitro-l-butene (Scheme 15) produces an a,P-abstraction product that reacts with alkyl halides and carbonyl compounds to give a mixture of the P- and 8-adducts. The 8-isomer can be separated and converted to an a,P-unsaturated aldehyde by Nef reaction with TiCb (equation 9). 

The interest in functionalized ionic liquids is growing because ionic liquids bearing ether, amino or alcohol functionalities have been shown to display special properties, including the ability to dissolve a larger amoimt of metal halide salts and to extract heavy metal ions from aqueous solutions. Imidazolium-based ionic liquids with ether and hydroxyl (see Section 2.2.1), thiourea, thioether and urea (see Section 2.2.8) " have been prepared following the standard quatemization procedure. A straightforward approach has been described for the preparation of imidazolium (as well as pyridinium) cations with ester, ketone or cyanide functionalities 1-methylimidazole reacts with methanesulfonic acid to provide the imidazolium salt 11, which undergoes a Michael-type reaction with methyl vinyl ketone as a ,j8-unsaturated compound to produce the ionic liquid 12 (Scheme 5). ... 

Ethyne may be condensed first with the alkyl halide to give H3C [CH2]a C=CH or with the difunctional entity to give Hcic(CH2)yY. The carboxyl group can be generated by oxidation of an alcohol or by reaction of halide with cyanide and then with acidic methanol to give a methyl ester. Condensation with acetylene or an ethynyl compound requires the sodium or lithium derivative and is usually conducted in liquid ammonia. Modification of this approach is necessary when the unsaturated centre is close to either end of the molecule. 

In Scheme 1.2, all of the types of carbonylations that are discussed in the book are depicted. Alcohols, amines, ethers, carboxylic acids and halides can be converted to acids, amides, esters, ketones, alkynones, alkenones, anhydrides and acid halides with the assistance of transition metal catalysts in the presence of a CO source. The CO sources used can be carbon monoxide gas, Mo(CO)6, Co(CO>6, formic acid, aldehyde, etc. If the starting material is alcohols or amines, some additives for activation are needed, such as BuONO, TsCl, AcCl. If the substrate is (Hetero)ArH, additional oxidants will be necessary this is a so-caUed oxidative carbonylation. If an unsaturated compound is to be carbonylated, a nucleophile NuH that carries an acidic hydrogen has to be present. In the case of insertion reactions, this is not necessary. 

There is a wide variety of reactants in this reaction. Suitable unsaturated starting materials or unsaturated compound-forming components are acetylenes, olefins, alcohols, cyclic and non cyclic ethers, epoxides, acetals, esters, saturated aldehydes, lactones and halides. Water, alcohols, ammonia, amines, mercaptans and carboxylic acids, e. g. are used as nucleophilic compounds with mobile hydrogen atoms. 

Oligosilanyl halides are also very abundant and their treatment as a separate compound class would thus be too exhaustive. Silyl halides are of major importance for the generation of numerous silicon species. By reaction with nucleophiles including lithium alkyls, silyl anions, amines, amides, alcohols, and alkoxides, Si-X bonds are easily formed. They also serve as starting materials for Si-Si bond formation by Wurtz coupling or for the generation of unsaturated compounds such as disilenes, disilynes, or silylenes. 

Preparation of Alkyl Halides.—We have spoken of the formation of the alkyl halides by the direct action of the halogen upon the saturated hydrocarbon. In the case of chlorine this action takes place at ordinary temperatures as in the reaction between methane and chlorine in the sunlight. Bromine, however, does not act directly at ordinary temperatures but by heating in a sealed tube. Iodine does not act directly with the hydrocarbons. In any case the result is a mixture of several substitution products, and the method is not, therefore, of practical value. Where direct action does not occur the presence of iodine chloride or antimony chloride, which act as carriers, is necessary. The two reactions of most importance in the preparation of these compounds are those involving either alcohols or unsaturated hydrocarbons. These will be taken up when these compounds are studied. 

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