Aliphatic chloro-compounds

Kester [5] has discussed the application of the purge and trap gas chromatographic method to the determination of aliphatic chloro-compounds in soil. Following methanol extraction of the soil the extract is gas purged and the purge gases trapped on a Tenax silica gel/ charcoal trap followed by thermal desorption from the trap and examination by gas chromatography and mass spectrometry. Compounds that have been determined by this method are listed in Table 5.1. 

Alkali metal and other iodides are effective catalysts in reactions involving aliphatic chloro and bromo compounds, such as the preparation of cyclopropane from 1,3-dichloropropane and metallic zinc (141). 

The thienopyrimidin-4(3f/)-ones 135 were converted into the corresponding 4-chloro derivatives 136 almost exclusively by heating with phosphoryl chloride containing A,N-dimethylanilme as catalyst. The 4-chloro compounds 136 were then treated with a variety of aliphatic and aromatic amines to afford the corresponding 4-alkyl or aryl aminothieno... 

Fluorophosphoranes are derivatives of phosphorus (V) fluoride of the composition R PF6 , where n = 1 to 3 and R may be an aliphatic or aromatic hydrocarbon group. Unlike the formally analogous and long-known chloro compounds, R PCl6 , fluorophosphoranes are typical covalent... 

Aromatic chloro compounds cannot be used for reactions with aliphatic cuprous mercaptides. 

The reactions of a-halocyclohexanones have been most thoroughly studied, and the reaction shown in equation (10), carried out on the molar scale, is an example. In general the chloro compounds provide larger yields than the bromo and fluoro analogs, and branched-chain aliphatic alkoxides are claimed to be the most effective bases. ... 

Halogen in positions other than next to the carboxyl group of aliphatic acids is somewhat less reactive. For preparation of methyl 4-(diethylamino)-butyrate from the 4-chloro compound the detour through the 4-iodo compound was chosen, this being easily accessible by means of sodium iodide.521... 

Studies of the kinetics of the reaction have been concerned principally with the liquid-phase ammonolysis of esters and aromatic chloro compounds, presumably because the reactions are more cleancut and there is less tendency to form by-products. For example, in the ammonolysis of esters, the amide is essentially the only product, whereas with the reaction of aliphatic alcohols and ammonia an equilibrium mixture of mono-, di-, and trialkylainines is obtained. 

Another synthesis of an aliphatic diazo compound in a two-phase system was reported by Moore and Arnold (1983). 4-Diazo-5-alkynyl-A-hexyl-5-methoxy pyr-rolidine-2,3-diones (2.17) were synthesized by nitrosation of the corresponding 3-chloro-4-amino-5-alkynyl-5-methoxy-A-Az-hexyl-3,4-pyrrolidenine-2-ones (2.16) in a mixture of dichloromethane and aqueous HCl at 0 °C (2-6). The overall reaction is probably a diazotization followed by a hydroxy-de-chlorination and a hydroxy-de-protonation. 

O.l-l.O Aliphatic Alcohols, Ketones, Aldehydes, Amines, Nitriles Monofluoro- and Chloro- Compounds. -OH -NHz O -CN Halogens... 

Lower aliphatic chloro- and bromoethers can be injurious to lungs. Many of these are cancer-causing to lungs in animals or humans. It is the carcinogenicity that makes some of these haloethers compounds of primary health concern. 

Organic aliphatic amines may react rapidly with HOCl to form N-chloro compounds. Methylamine, for example, reacts nearly 100 times as fast as ammonia with HOCl (Morris, 1967). In general, the rates of these reactions parallel the basicities of the amines, although steric and other effects undoubtedly play important roles. Morris (1967) has shown excellent correlation of reaction rate with pKb over many orders of magnitude of the latter parameter (Figure 5.11). Tertiary amines were converted to secondary N-chloro compounds and carbonyl compounds derived from side-chain cleavage (Ellis and Soper, 1954). The mechanism of this reaction... 

Preparations.—a-Mercapto-a-amino-acids R NHCR (SH)C02H are obtained from corresponding chloro-compounds or from 4-chloro-oxazol-5(4H)-ones. Conventional methods are also used for synthesis of thio-resorcinols (from benzene-1,3-disulphonic acids via sulphonyl chlorides, reduced with red P-Ir-AcOH, or from resorcinols via Newman-Kwart rearrangement of O-dimethylaminothiocarbonyl-resorcinols followed by alkaline hydrolysis ). Dithiols are unexpectedly obtained from ethyl a-acetonylacetate by treatment with H2S in acid solution at -40 "C. Mercapto-ethylation of aliphatic amines is best achieved by a modificaticm of the well-established method using episulphides, in aqueous solution in the presence of a silver salt. Methyl sulphides ArSMe may be demethylated by chlorination to ArSCCh followed by acid methanolysis, while aryl diphenylmethyl sulphides are susceptible to electrolytic reduction to the thiophenol. ... 

The iodine atom in iodobenzene (unlike that in the corresponding aliphatic compounds) is very resistant to the action of alkalis, potassium cyanide, silver nitrite, etc. This firm attachment of the iodine atom to the benzene ring is typical of aromatic halides generally, although in suitably substituted nitio-compounds, such as chloro-2,4-dinitrobenzene, the halogen atom does possess an increased reactivity (p. 262). 

Preparation. Thermal elimination of HCl from l-chloro-l,l-difluoroethane (HCFC-142b) [75-68-3] is the principal industrial route to VDF covered by numerous patents (8—19). Dehydrohalogenation of l-bromo-l,l-difluoroethane (20), or 1,1,1-trifluoroethane (HFC-143a) (21—25), or dehalogenation of l,2-dichloro-l,l-difluoroethane (26—28) are investigated alternative routes (see Fluorine compounds, organic-fluorinated aliphatic compounds). 

Particularly the chlorinated compounds have enjoyed range of applications vinyl chloride (chloro-ethene) as monomer for the production of PVC, tetra- and trichloroethenes as solvents for degreasing, and the insecticides l,l,l-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and isomers of hexachlorocyclohexane (HCH) (benzene hexachloride). The biodegradation of fluorinated aliphatic compounds is generally different from the outlines that have emerged from investigations on their chlorinated, brominated, and even iodinated analogues. They are therefore treated separately in Part 4 of this chapter. 

Chloro- and sulfonamide-substituted aromatic amides showed decreased binding affinity and in vivo potency compared to the simple aliphatic amides. Side chains with an additional (CH2)i-2 linker between the amide and the phenylsulfonamide group resulted in partial or absent in vivo effects [113]. The (CH2)-linked compound, (153), showed around 80-fold selectivity for CB2 over CBi binding [107]. 

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