Long-chain halides

With the purpose of improvement and simplification of the synthesis of potential cosmetic compounds, alkylation of mono- and dihydroxybenzaldehydes with long-chain halides was efficiently realized under solvent-free MW + PTC conditions (Eqs. 16 and 17 and Tab. 5.9) [27, 28],... 

Long-chain halides undergo this reaction at 100°, no C-dialkylated products being formed. In alkylations with aryl-substituted alkyl halides, Ar(CH,) X, n= 1 to 3, yields are improved by performing the reaction rapidly in liquid ammonia (56-9S>%). Also, quinoline methylated in the 2-or 4-position reacts in the same way. A methyl group in the 3-position of pyridine or quinoline is unreactive. 

With very long-chain halides, the only working procedure is the solvent-free one [Eq. (49)]. 

This lactonic diol, byproduct of sugar beet, can be converted to acetals with crystal-liquid properties when treated with long-chain halides. 

Sodium sulfide reacts with aqueous alcoholic solutions of the halides to give good yields of the symmetrical sulfide. Halides containing fi-carboxy, hydroxyl, ethoxyl, or diethylamino groups are effective in this reaction. Long chain halides give cyclic sulfides. 

Alkyl halides are more easily identified than the dichloro halides. Figure 17.1 shows the mass spectra of two dichlorohexanes. Long-chain saturated halides may also lose an alkyl portion from the molecular ion, such as 15, 29, 43, 57, 71, 85, and 99 Daltons. These can be identified as halogenated compounds, but it is difficult to deduce their molecular weights without Cl or negative Cl. 

Their physical properties are essentially those of the alkanes. It is the unsaturated linkages that dominate the chemistry and the main reaction is one of addition (e.g. hydrogen, halogen, and hydrogen halides) across the double bond to produce saturated compounds. This reactivity is utilized in the manufacture of long-chain polymers, e.g. polyethylene and polypropylene. 

In addition to 1,2-hydride shifts, the 1,5-hydride shift is favoured [24] in the decomposition of radical-cations of long chain alkyl halide such as 10. 

Coupling of Grignard reagents with primary halides and tosylates can by catalyzed by Li2CuCl4.29 This method, for example, was used to synthesize the long-chain carboxylic acid 1 in >90% yield. 

Sodium salts of carboxylic acids, including hindered acids such as mesitoic, rapidly react with primary and secondary bromides and iodides at room temperature in dipolar aprotic solvents, especially HMPA, to give high yields of carboxylic esters.679 The mechanism is Sn2. Another method uses phase transfer catalysis.680 With this method good yields of esters have been obtained from primary, secondary, benzylic, allylic, and phenacyl halides.681 In another procedure, which is applicable to long-chain primary halides, the dry carboxylate salt and the halide, impregnated on alumina as a solid support, are subjected to irradiation by microwaves in a commercial microwave oven.682 In still another method, carboxylic acids... 

Long-chain alkylphosphonium azides and thiocyanates have been used as a source of anionic nucleophiles in the reaction of n-octyl halides and esters (n-octX X = Cl, Br, I, OTs, OMs) a substitution process is able to occur even in non-polar solvents909. 

Several approaches to artificial photosynthesis involve the mimicking of membranes to effect charge separation. An easy extension of the micellar effects described above to systems amenable to study as photosynthetic models can be encountered in the charge separation derived on synthetic vesicles or membranes (275). Sonic dispersal of long chain ammonium halides, phosphates, sulfonate, or carboxylates produces prolate ellipsoidal vesicles with long term stabilities which can entrain and trap molecules in their compartments. With donor-acceptor photosystems, four physical arrangements about the vesicle are important, Fig. 6. 

The quaternary ammonium compounds (qv) are manufactured by the reaction of an alkyl halide with a tertiary amine. The alkyl halide may be short-chain, long-chain, or benzyl. Selection of a long-chain alkyl group yields structures with variable composition and greatly adds to the chemical complexity inherent in this group. Investigation of structure-activity relationships has led to claims for superior efficacy or compatibility, most notedly with anionic surfactants in disinfectant-detergent cleaner systems, of closely related compounds in the family. 

Alkyl ethers of sucrose have been prepared by reaction with long-chain alkyl halides to provide mixtures of regioisomers and products of different degree of substitution.82,83 A similar reaction with chloromethyl ethers of fatty alcohols provides formaldehyde acetals.84,85 Alkenyl ethers of various carbohydrates, and notably of sucrose, can also be obtained by palladium-catalyzed telomerization of butadiene (Scheme 6).86 88 Despite a low-selectivity control, this simple and clean alternative to other reactions can be carried out in aqueous medium when sulfonated phosphines are used as water-soluble ligands. 

Ammonia present in the sample also contributes to COD. However, in presence of excess free Cl-, it is converted into HH4C1 and is not oxidized. Long chain aliphatic compounds are often difficult to oxidize. A catalyst, Ag2S04, is therefore added to promote such oxidation. Halide ions present in the sample may, however, react with Ag2S04 forming silver halide. Such halide interference may be partially overcome by adding HgS04. 

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