Unsaturated Halogen Compounds

For a long time, it was considered that unsaturated halogen compounds could not be hydroformylated. It was reported that the cobalt catalyst would be halogenated and also that the dehalogenated product could not be hydroformylated. 

Vinyl chloride a-Cl-propionaldehyde, acrolein, propionaldehyde, ethyl chloride 85-90 [291, 292] 

Recently, some halogenated materials have been found which can be reacted with synthesis gas. These are compounds which have the halogen relatively tightly bound chlorinated aromatics [289], perfluoro olefins [290] or vinylic chloride compounds [291, 292] (table 22). 

---

Unsaturated halogenated compounds with a central C = C or C = C bond undergo cleavage on oxidation in the middle of the molecule and form two carboxylic acids without loss of a carbon atom. The reaction mechanism of the oxidation of internal fluoroalkenes by potassium permanganate includes hydroxylation of the C = C bond in 2 by permanganate, accompanied by dehydrofluorination of the geminal fluoroalkane-1,2-diol 3 and formation of an intermediate fluorocarbonyl compound 4 oxidative cleavage of the C-C bond in 4 leads to the final products 5.1... 

Table VH. Hydroformylation of Unsaturated Halogen Compounds Table VIH. Hydroformylation of Un.saturated Nitrogen Compounds Table IX. Hydroformylation of Other Functionalized Alkenes. ...

TABLE VIL HYDROFORMYLATION OF UNSATURATED HALOGEN COMPOUNDS (Continued)... 

When acetone is treated with phosphorus pentachloride, the oxygen atom is replaced by two halogen atoms. An unsaturated halogen compound is also formed as the result of the elimination of hydrogen chloride —... 

Under these conditions nearly all olefins and a great number of dienes, unsaturated carboxylic acid esters, unsaturated and saturated alcohols and diols, reactive cycloparaffins, saturated and unsaturated halogenated compounds, N-tertiary alkyl acyl amines, carboxylic acid esters and saturated... 

Carboxylic acids are also formed starting with saturated instead of unsaturated halogenated compounds if severe reaction conditions are applied [591]. 

Unsaturated Polyesters. There are two approaches used to provide flame retardancy to unsaturated polyesters. These materials can be made flame resistant by incorporating halogen when made, or by adding some organic halogen compound when cured. In either case a synergist is needed. The second approach involves the addition of a hydrated filler. At least an equal amount of filler is used. 

It is only in relatively recent years that the interaction of indole Grignard reagents with unsaturated aliphatic halogen compounds has... 

Despite the increasing information on the photochemistry of 2,4-dienones and other unsaturated ketones, as well as on the ring-chain valence isomerism of halogen-substituted pyran and dihydi opyran systems,the data are still very scarce. The intermediate formation of pyrans valence-isomeric with unsaturated carbonyl compounds in the pyridine syntheses based on reactions of ammonia with aldehydes or ketones, advocated by various authors (cf. Section II,B,2,f), is still rather speculative. (See also Section II,B,2,e for the valence isomerism of 5-chloro-2,4-dienones with pyrylium chlorides.)... 

Other important applications for organoboranes" include the Michael-like addition reaction to a ,/3-unsaturated carbonyl compounds, and the alkylation of a-halogenated carbonyl compounds. 

Hell-VoLhard-Zelinskii (HVZ) reaction, in which an acid is treated with Bc2 and PBr3. The a-halogenated products can then undergo base-induced E2 elimination to yield a,j6-unsaturated carbonyl compounds. 

Little is known about the tolerance of 1 with unsaturated (poly)halogen compounds. Hydrozirconation of chloroalkenes can lead to competitive cycUzation, and simple reduction of both C=C and C-Cl bonds [98, 222], However addition of 1 to an alkenyl- or propargyl bromide led to the expected product as the sole product of the reaction in excellent yield (Scheme 8-30) [134, 223]. 

Like aldehydes and ketones, the a-hydrogens of acid and acid derivatives are acidic and can be abstracted with base to generate the carban-ions, which can then react with various electrophiles such as halogens, aldehydes, ketones, unsaturated carbonyl compounds, and imines, to give the corresponding products. Many of these reactions can be performed in aqueous conditions. These have been covered in related chapters. 

Dissociation of Halogen-Containing Compounds. Halogenated compounds, particularly those containing bromine or iodine, are likely to undergo photoelimination of the halogen atom. p-Bromobutyrophenone (7) yields butyrophenone, HBr, and butyrophenones with unsaturated alkyl side chains when irradiated in toluene.25,44 The quantum yield for butyrophenone... 

The /S-bromodihydropyran (652) on halogen-metal exchange with f-butyllithium affords a useful organometallic (653) that can function as the equivalent of a 5-hydroxy aldehyde enolate (Scheme 151) (79TL67). The vinyllithium species adds to ketones and aldehydes at -110 °C in good yield and also reacts in a conjugate mode with a,/S-unsaturated carbonyl compounds in the presence of copper(I) ions. On hydrolysis and oxidation, the dihydropyran component (654) can be transformed into a substituted 5-lactone (655). 

There has been a growing interest in applying high performance liquid chromatography, to the determination of the not only volatile compounds, such as aliphatic and polyaromatic hydrocarbons, saturated and unsaturated aliphatic and polyaromatic hydrocarbons, saturated and unsaturated aliphatic halogen compounds, haloforms and some esters, phenols and others but also non volatile components of water. 

---