Halogen compounds alicyclic

Hexafluoroacetone has been a popular compound for further photochemical study" " Majer et al. have reported on the photolysis of alicyclic perfluoroketones and of chloropentafluoroacetone other work on fluorinated ketones has been reported by Pritchard et a/. - , by Phillips and Trotman-Dickenson , and by Schuster and Patel . Intramolecular elimination reactions in the photolysis of fluoroaldehydes have been discussed by Morris and Thynne and by Pritchard and Perona . Photolytic studies on other oxygen-containing halogen compounds have included chloroacetic acids , acetyl chloride , perfluoroacyl fluorides , CF3OF and CF3OOCF3 . 

Halogenated derivatives of the same kind are much more radiation resistant for aromatic than for alicyclic compounds. The resulting order is aromatic > ionic > alicyclic. Even when the... 

Kishi, H., Kogure, N., Hashimoto, Y. (1990) Contribution of soil constituents in adsorption coefficient of aromatic compounds, halogenated alicyclic and aromatic compounds to soil. Chemosphere 21, 867-876. 

As revealed in the following three sections, work dealing with the electrochemical oxidation of halogenated organic compounds is centered largely on the behavior of alkyl, alicyclic, and aryl halides. A review by Becker [4] provides an especially good perspective of developments in these areas. 

Usually, 3- and 4-substituted thianes are prepared from the 3- and 4-oxothians by the common techniques applicable to alicyclic chemistry. Reduction affords alcohols which may be etherified or halogenated, while oximation and reduction produces the amino derivatives, which are also accessible via the halo compounds. 2-Alkoxy and 2-alkylthio compounds are made by acid catalyzed addition of alcohols and thiols to 3,4-dihydro-2H-thiopyran (75MI22502) in a reaction analogous to the use of dihydropyran for protection of alcohols as THP ethers. 

Removal of ring halogen atoms resulting in fluoroaromatic compounds has recently been reviewed.172 Most dehalogenations of halogenated alicyclic compounds are carried out at pyrolytic temperatures (330-600 C) in the gas phase over iron or iron oxides,126 128,130-132 while arynes are often synthesized by dehalodefluorination of o/7/to-halofluorobenzenes. Table 5 lists examples of dehalogenations which provide fluoroaromatic compounds. 

Table 5. Formation of Fluoroaromatic Compounds by the Dehalogenation of Halogenated Alicyclic Compounds...

The halogenated acyclic marine monoterpenes are often considered to be the biogenetic precursors of the alicyclic monoterpenes that are presented in this section. Many of the preceding algae species also contain cyclic monoterpenes. As was the case in preceding sections only newly characterized compounds are numbered and the reader is referred to the first survey for structures of previously isolated compounds (7). 

The application of the displacement of halogen by nickel-aluminum alloy in aqueous alkali to the quantitative determination of halogens in organic compounds (115) is of considerable interest. Many of the above methods, when adapted for analysis, require the use of hydrogen gas, a prepared catalyst, and a hydrogenation apparatus of the conventional type. These requirements are obviated by the use of nickel-aluminum alloy in aqueous alkali, and the method is advantageously used for the quantitative determination of halogen in many aliphatic, aromatic, alicyclic, and heterocyclic compounds. 

Triazolium salts (49 Scheme 23), prepared from an acid chloride and the thiohydrazo compound (48), have been reduced to the hydro compound (50) and then hydrolyzed in dilute sulfuric acid to the aldehyde. - Overall yields of aldehyde are reported to be 46-90% and a variety of other functional groups can be supported such as alkene, halogen, nitro, ketone and ester there can be one or two side chains on the a-carbon or it can be part of an alicyclic system. 

As the number of carbon atoms at the fifth carbon position increases, the lipophilic character of the substituted barbituric acids also increases (44). Branching, unsaturation, replacement of alicyclic or aromatic substituents for alkyl substituents, and introduction of halogen into the alkyl substituents all increase the lipid solubility of the barbituric acid derivatives. A limit is reached, however, because as the lipophilic character increases, the hydrophilic character decreases. Although lipophilic character determines the ability of compounds to cross the blood-brain barrier, hydrophilic character also is important, because it determines solubility in biological fluids and ensures that the compound reaches the blood-brain barrier. Introduction of polar groups into the alkyl substituent decreases lipid solubility below desirable levels. Modifications at this position by variation of the alkyl substituents were of primary importance in the development of barbiturates with short (3-4 hours) to intermediate (6-8 hours) duration of action. These barbiturates were once extensively used as sedatives and hypnotics. 

As additive flame-retardants, low-molecular halogenated aliphatics are used, like hexachloroethane (CI3C—CCI3) or chlorinated paraffins. Brominated aliphatics, such as tetrabromoethane (Br CH - CHBrg) are preferably suggested for foams because of their lower processing temperature. Alicyclic compounds such as hexabromo-cyclododecane are readily compatible with polystyrene and efficient in relatively low proportions. 

Kishi, H., N. Kogure, and Y. Hashimoto. Contribution of Soil Constituents in Adsorption Coefficient of Aromatic Compounds, Halogenated Alicyclic and Aromatic Compounds to Soil, Chemosphere, 21(7) 867-876 (1990). 

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