4,4 -Diphenyldicarboxylic acid

We have been working on the preparation of novel LCPs from substituted HQs and substituted l,2-bis(phenoxy)ethane-4,4/-dicarboxylic acids (PECs) [18], and substituted HQs and 4,4-diphenyldicarboxylic acid (BB) [19-21],... 

The Suzuki reaction97 allows tire coupling of two aromatic rings by reaction of an arylboronic compound with a iodo or bromo aryl derivative. The tetrakis (U iphenylphosphine) Pd is the catalyst working in the basic medium. This reaction was recently used98 in aqueous media for the preparation of different isomers of diphenyldicarboxylic acids (Fig. 5.21) but also for the synthesis of soluble rodlike polyimides99 by coupling the 3,6-diphenyl- V, V,-bis(4-bromo-... 

Similar observations were reported for tetrachloro-2,2 -diphenyldicarboxylic acid dichloride237 and 1,1 -binaphthyl-2,2 -dicarboxylic acid dichloride239-240. 

Diphenyldicarboxylic acid see Biphenyldicarb-oxylic acid 2 B125... 

Esterification. An esterifying reagent can be prepared easily by mixing boron trifluoride etherate in an alcohol. This reagent is both thorough and mild. Thus p,//-diphenyldicarboxylic acid, which is inert to diazomethane, is converted into the corresponding dimethyl ester in 40% yield when refluxed in 10% boron trifluoride etherate in methanol for three days. The very sensitive 1,4-dihydro-benzoic acid was successfully esterified by this method. The ethyl ester was obtained in 81% yield when the acid was refluxed for 20 hours in anhydrous ethanol containing boron trifluoride etherate.1... 

We expected that polyarylates derived from 4,4 -diphenyl-dicarboxylic acid(BB) would show increased stability of the liquid crystalline state compared with PEC due to the longer mesogen unit,but at the same time,we were afraid that melting temperatures(Tms) of these polyarylates would be very high because Tm of poly(ethylene 4,4 -diphenyldicarboxylate) was much higher than that of poly(ethylene terephthalate) and poly(methylhydroquinone terephtalate)(Me-HQ/TA) showed no liquid liquid crystallinity even at the temprature above 450 C. 

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