Chlorophenyl groups

Sihcone oils are good hydrodynamic lubricants but have generally poor frictional lubricating properties (352—354). The latter can be improved by incorporating chlorophenyl groups into the polymer side chains (355). For steel on steel, the coefficient of friction is about 0.3—0.5. The load-bearing capacity of PDMS (Almen-Wieland machine) is only 50—150 kg, compared with - 1000 kg for polychlorophenyLmethylsiloxane and up to 2000 kg for mineral oil. 

Cleavage of the bromophenyl group is achieved with Cu(OAc)2 in Pyr, H2O. The 2-chlorophenyl group is stable to these conditions. ... 

The present synthesis10 consists of two simple steps, uses readily available and inexpensive starting materials, and produces pure material in high overall yield. It is based on two observations that nonenolizable ketones may be cleaved to carboxylic acids by potassium ferf-butoxide-water,2 and that aryl 2 chlorophenyl ketones may be cleaved with loss of the 2-chlorophenyl group to give only one of the two possible acids.11 Other compounds prepared by this route include carboxycyclopentadienyltriearbonylmanganese [Manganese, tricar-bonyl[(l, 2,3,4,5- )-l-carboxy-2,4-cyclopentadien-l-yl]-] (79%)10 and... 

The p-chlorophenyl group is in fact itself a protecting group which was not removed until a late stage in the synthesis. 

Ethyl substitution at the imidazole 5-position (469) was found to increase potency over the unsubstituted analogue (468), while methyl substitution (470) had a slightly deleterious effect on binding (Table 6.41). Chloro (491), bromo (492), cyano (493) and fluoromethyl (494) substitution at this position were all well tolerated (Table 6.43). Introduction of a chloro-substituted pyridine (475) in place of the more usual / -chlorophenyl group (470) resulted in a slight loss of affinity for the CBi receptor, as did replacement of the p-chloro group of (470) with bromo (471), fluoro (472) and in particular, met-hoxy (473). Trifluoromethyl substitution (474) however, was well tolerated. 

The enantioselective photoreaction of 50 to 52 in the complex (57) can be interpreted as follows disrotatory [2 + 2]-photoreaction of 50 in 51 occurs only in the A direction according to a steric hindrance of the o-chlorophenyl group of 2a (Scheme 4)29 30). This interpretation was determined as reasonable by X-ray crystal structural study of 51b (Fig. 12)32). 

Bedard et al. [245] reported that PCB dechlorination was stimulated by adding 2,5,3, 4 -tetrachlorobiphenyl (25-3 4 -CB) to slurries (incubated under methanogenic conditions) of sediments contaminated with Aroclor 1260 from Woods Pond (MA). The 25-3 4 -CB was converted stoichio-metrically to 25 - 3 -CB and stimulated a selective para-dechlorination which decreased the penta- through heptachlorobiphenyls containing 234-, 245-, or 2345-chlorophenyl groups by up to 83% in 12 weeks. 

It was postulated that the interactions between the bulky 3-chlorophenyl group and the methyl substituents at C2 and C5 would generate significantly higher energy conformations for the (U.S)- and (S,JJ)-enantiomers. Hence, steric constraints and... 

The stereochemistry of the reaction depended on the substrate in some favourable cases a single stereoisomer was formed, whereas in others mixtures of a,/ -isomers were obtained. An increase in yield was noted when the phenyl group of the thioglycoside was replaced by the 4-chlorophenyl group. Another useful fluorination involved xanthate esters, ROCSSMe, readily obtained from alcohols these upon reaction with 4-(difluoroiodo)toluene were converted into alkyl fluorides in 48-75% yield [54],... 

Adsorbed films of ethykriethoxysilane and vinyltriethoxy-silane were formed on silica and alumina by retraction from hydrocarbon solution and their wettabilities and water-stabilities determined. The vinyltriethoxysilane films were generally more oleophobic, more hydrophobic and more resistant to contact with water than the films formed by the ethyl analog. Neither adsorbate formed stable films on a-alumina. The addition of low molecular weight organic acids or bases to the adsorbate solution resulted in both the ethyl and vinyl compound forming hydrophobic and water-stable films on silica and ot-alumina. Films of p-chloro-phenyl-ft-ethyltrichloro, -trimethoxy, and -triethoxysilane were also studied and found to be water-stable and to have wettabilities characteristic of a surface comprised of closely-spaced p-chlorophenyl groups. 

---