Hydroquinone oligomers

It should be noted that one of these diols, the hydroquinone, did not provide any oligomer in the first step. This was due to the formation of the quinone structure which made it impossible to use hydroquinone directly in the substitution reaction. An alternate method was used to overcome this problem which involved the use of 4-methoxyphenol to obtain the sulfone product, followed by cleavage of the methyl ether to the diol (VIII) with boron tribromide. This set of reactions is outlined in Figure 5. 

The oxidation products of acrolein were analyzed mainly by gas chromatography (22). Peracrylic acid and peroxides were determined by the method of Greenspan and McKeller (16). The polymeric products of the oxidation were measured as follows. At the end of the reaction, the reactor was cooled rapidly and hydroquinone was added. Then insoluble polymers containing oligomers were collected on a filter, dried, and weighed. 

Various oligomeric and polymeric stabilizers containing PC units were synthesised. Oligomers prepared from phosgene and 4,4 -isopropylidenebis(2-re/ r-butylphen-ol), or 2,5-bis(2-hydroxyethyl)hydroquinone, from diphenyl carbonate and 4,4 -isopropylidenebisphenol,4,4 -butylidenebis(6-rcrt-butyl-3-methylphenol), or substituted monohydric and dihydric mononuclear phenols, e.g. l-(3,5-di-tert-butyl-4-hydroxyphenyl)-3,3-bis[(3-terr-butyl-4-hydroxyphenyl)butane] carbonate (155)... 

Photo-cross-linkable oligophenols were synthesized by the HRP-catalyzed polymerization of cinnamoyl-hydroquinone-ester and cinnamoyl-4-hydroxyanilide in an aqueous 1,4-dioxane.40 UV irradiation of the oligomer films induced the cross-linking by the photochemical [2+2]-cycloaddition of the cinnamoyl function. 

Yurteri et al. [164] suggested a different approach. The coupling of the oligomers is realized by using organic molecules such as hydroquinone in the presence of K2CO3 and DMF. They showed that a quantitative coupling rate required an exact stoichiometry (Scheme 27). 

Chlorophenol gave a variety of photoproducts, including hydroquinone, benzo-quinone, and several hydroxylated and/or chlorinated biphenyls (Boule et al., 1987). In addition, higher oligomers containing polyphenyls with up to 5 units were identified after prolonged irradiation. 

Hydroquinone Bisphenol A, and 4 -hydroxy phenyl-4-hydroxybenzoate 4,4 -Dihydroxybenzophenone PEEK oligomer Catechol (4-(4 -Trifluoromethyl)phenoxyphen-yl)hydroquinone and hydroquinone 4,4 -Difluorodiphenyl ketone 4,4 -Difluorodiphenyl ketone 4,4 -Dichlorodiphenyl sulfone" 1,5-Bis-(4-(4 -fluorobenzoyl)-phen-oxy)-naphthalene (1,5-BFPN) 4,4 -Difluorodiphenyl ketone 4,4 -Difluorodiphenyl ketone ... 

Cyclic oligomers formed in the synthesis of isomeric polyesters obtained by condensation of phthaloyl chloride and catechol (Polyester 1), resorcinol (Polyester 11), or hydroquinone (Polyester 111) (Scheme 7.3), respectively, were characterized by FAB-MS. ... 

Thermotropic polycarbonates have been prepared from mixtures of 4,4-dihydroxybiphenyl and various diphenols (12). Nematic melts were found for copolycarbonates prepared from methylhydroquinone, chlorohydroquinone, 4,4-dihydroxydiphenyl ether, and 4,4-dihydroxybenzophenone. Slightly crystalline polycarbonates have been prepared from mixtures of hydroquinone and BPA (14) [Tg = 154°C, Tm = 313°C, AiT = 11.0 J/g (2.63 cal/g)l, and ahighly crystalline, high heat polycarbonate has been prepared from methylhydroquinone (21) [Tg = 155°C, Tm = 289°C, AH = 31.0 J/g (7.41 cal/g)]. While the former (hydroquinone-BPA) copolymer has only been prepared via cyclic oligomers, the methylhydroquinone polycarbonate can be prepared via a melt process. 

Extended exposure of acetic anhydride solutions of monomer to UV light, in the presence of 1% biacetyl, gives polymeric material in about 15% yields/MA oligomers, containing aromatic residues, have also been obtained from the benzophenone-sensitized photopolymerization of MA in a variety of aromatic solvents/ These sunlight-induced polymerizations were not inhibited by hydroquinone or /-butylhydroquinone. 

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