Diphenyl carbonate, preparation

Diphenyl carbonate [102-09-0] M 214.2, m 80 . Purified by sublimation, and by preparative gas chromatography with 20% Apiezon on Embacel, and crystn from EtOH. 

These materials have the general structure shown in Figure 20.11 and are prepared by reaction of bisphenol A with iso- and/or terephthalic acid and a carbonate group donor (e.g. phosgene or diphenyl carbonate). 

Lexan, a polycarbonate prepared from diphenyl carbonate and bisphenol A, is another commercially valuable polyester. Lexan has an unusually high impact strength, making it valuable for use in telephones, bicycle safety helmets, and laptop computer cases. 

Preparation of a Polycarbonate from 4,4-lsopropylidenediphenol (Bisphenol A) and Diphenyl Carbonate by Transesterification in the Melt... 

Cyclic carbonates are not commercially available and have to be synthesized prior to use. As a result, commercially available carbonates such as diethyl carbonate [55-57] or diphenyl carbonate [93] were evaluated in polycondensation reactions with diols to prepare polycarbonates since they allow a broader spectrum of polymers to be accessed. Unfortunately, polymerizations employing diethyl carbonate require the use of an excess diethyl carbonate [55]. Nevertheless, polymers with molecular weight of 40kDa were achieved within 16 h. Also, the polymerization of diphenyl carbonate with butane-1,4-diol or hexane-1,6-diol via the formation of a cyclic dimer produced polymers with molecular weights ranging from 119 to 339kDa [93]. 

Carboxy-terminated oligomeric polyester compositions consisting of resorcinol, terephthalic isophthalic acid, diphenyl carbonate, and terephthalic acid catalyzed by titanium tetrabutoxide were prepared by Brunelle et al. (1) and used as thermosetting applications. 

TABLE 1. Physical Properties of Step 1 Products Prepared by Condensing Diphenyl Carbonate with Selected Thiols Prepared According to the Current Invention... 

Copolycarbonates, (I), consisting of isosorbide, bisphenol A, and diphenyl carbonate were prepared by Dhara et al. (4) and used as optical waveguides. 

Diphenyl carbonate is an important intermediate in the production of bisphenol-A-polycarbonate (BPA-PC). The technology shift from phosgene to DPC to produce BPA-PC on a commercial scale also allows the number of applications of this type of polymer to be increased for example, high-performance BPA-PCs utilized for information storage (e.g., DVDs) are prepared from high-purity DPC. The chemical route to this DPC brand is based on a two-step reaction, namely transesterification followed by disproportionation (Equations 7.4 and 7.5). 

Carbohydrazide has been prepared by the reaction between diphenyl carbonate and hydrazine hydrate1 and also by the action of dilute acid on tris(benzalamino)guan-idine.2 Curtius and Heidenreich3 synthesized carbohydrazide by long refluxing of a mixture of diethyl carbonate and hydrazine hydrate. Kesting4 increased the yield by distilling off volatile products and unreacted materials after the 48-hour reflux period. 

Howwjanz discovered that a large number of carbohydrates and poly-hydric alcohols can combine with carbon dioxide in the presence of excess milk of lime to form unstable acid carbonate salts, R—0—CO—0 M . Stable, neutral esters of carbonic acid with carbohydrates were first prepared in 1912 by Hochstetter, who patented a process involving reaction with diphenyl carbonate at about 130°. However, not one of the examples cited—derivatives of D-glucose, sucrose, D-mannitol, and starch—was completely characterized and, possibly on account of the rather drastic conditions used, Hochstetter s method has not received attention from later workers. 

Vator in 1935. Hochstetter reported the preparation of carbonates of D-glucose, D-mannitol, sucrose, and starch by heating the appropriate carbohydrate to 130° with diphenyl carbonate in a medium of molten resorcinol or catechol. The products, the first two of which were crystalline, were purified by removal of the liberated phenol in high vacuum, followed by repeated solvent extraction. No characterization appears to have been carried out, apart from noting that boiling water slowly hydrolyzes the derivatives to carbon dioxide and the original carbohydrate. 

Polycarbonate resins were prepared by reacting diphenyl carbonate with bisphenol A and isosorbide. These resins had light transmissions exceeding 90% with little or no haze. As a result of the favorable elastic modulus and hardness properties, these resins were scratch resistant. 

TABLE 1. Polycarbonates prepared by reacting diphenyl carbonate with isosorbide and bisphenol A. 

Optically active poly[(isosorbide-co-bisphenol A) carbonate)], (11), was also prepared and consisted of 90% isosorbide and 10% bisphenol A with diphenyl carbonate and had an optical rotation of 140° with excellent scratch resistance. 

Glasgow [1] prepared a blend consisting of the reaction product of bisphenol A and diphenyl carbonate with poly(caprolactone-b-dimethylsiloxane-b-poly-caprolactone) terpolymer that showed superior resistance to scratching and haze while having excellent transmittance properties. Food and medical articles derived from this blend were readily sterilized by steam at atmosphere pressure as taught by Chatteijee [2]. 

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)... 

Problem 30.18 Lexan can also be prepared by the acid-catalyzed reaction of diphenyl carbonate with bisphenol A. Draw a stepwise mechanism for this process. 

Among the numerous applications of diphenyl carbonate, the preparation and chemistry of dichlorodiphenoxy methane appears somewhat neglected. This phosgene derivative can be prepared in good yield by treatment of diphenyl carbonate with phosphorus pentachloride at high temperature (Ref. 35) according to scheme 37 ... 

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