Bisphenols cleavage

The acetone supply is strongly influenced by the production of phenol, and so the small difference between total demand and the acetone suppHed by the cumene oxidation process is made up from other sources. The largest use for acetone is in solvents although increasing amounts ate used to make bisphenol A [80-05-7] and methyl methacrylate [80-62-6]. a-Methylstyrene [98-83-9] is produced in controlled quantities from the cleavage of cumene hydroperoxide, or it can be made directly by the dehydrogenation of cumene. About 2% of the cumene produced in 1987 went to a-methylstyrene manufacture for use in poly (a-methylstyrene) and as an ingredient that imparts heat-resistant quaUties to polystyrene plastics. 

Spivack J, TK Leib, JH Lobos (1994) Novel pathway for bacterial metabolism of bisphenol A. Rearrangements and stilbene cleavage in bisphenol A metabolism. J Biol Chem 269 7323-7329. 

Since poly(oxy-2,6-dimethy1-1,4-phenylene) has exhibited a high tendency to undergo cleavage, rearrangements and to crosslink in the presence of electrophilic reagents,21 our attention has been focused on modification of poly(arylene ether sulfone), 1, and phenoxy resin,4 The active sites in these polymers are the 3-positions of the bisphenol-A repeating units. We will report the extent of... 

The FTIR spectra of the gas mixture evolved in thermal decomposition of Bisphenol AF poly(formal) (7) at various temperatures suggest the existence of benzene rings, C—O—C bonds, and C=C bonds. In a pyrogram of pyrolysis gas chromatography (Py-GC) of Bisphenol A (3), a-methylstyrene, phenol, p-cresol, 4-hydroxy-amethylstyrene, and isopropyl phenol are observed as major peak products. The cleavage reactions shown in Scheme (5) is suggested for the formation of phenol and 4-hydroxy-a-methylstyrene from Bisphenol A (3). 

In a pyrogram of Bisphenol A poly(formal) (6), the peak products are identified as a-methylstyrene, phenol, 4-hydroxy-a-methylstyrene, and isopropyl phenol by Py-GC/MS. These products are identical with the degradation products from Bisphenol A. In addition to the decomposition products of Bisphenol A, 4-isopropenyl anisole is also identified as a product. The pyrograms of Bisphenol AF poly(formal) (7) contain only two major species, pentafluoroisopropenyl benzene (product T) and pentafluoroisopropenyl anisole (product 2 ). They correspond to a-methylstyrene, 4-hydroxy-amethylstyrene from Bisphenol A poly(formal) (6) and are produced by the cleavage of phenylene-oxy bonds and oxy-methylene bonds according to (Scheme 6). 

Wooley et al.1511 have described the creation of fullerene-bound dendrimers (Scheme 5.14). Reaction of C60 with bis(p-methoxyphenyl)diazomethane 54 and subsequent cleavage of the methyl ethers afforded a 6-6 methano-bridged fullerene (55) possessing two phenolic moieties, as the major product.1521 Treatment of the bisphenolic fullerene 55 with 2.7 equivalents of the activated dendron (52) afforded the desired substituted fullerene (56) possessing two dendritic arms. 

Pyrolysis in the presence of tetramethylammonium hydroxide (TMAH) at a lower temperature of 300° C was studied for both PES and PSF [11]. In this study, the main component for the thermally assisted hydrolysis and methylation of PES was dimethyl derivative of bis(4-hydroxyphenyl)sulfone. This compound was formed through selective cleavages of ether linkages maintaining intact the sulfone structures. For PSF thermally assisted hydrolysis and methylation at 300° C, the main constituents were dimethyl derivative of bis(4-hydroxyphenyl)isopropylidene (bisphenol A) and also dimethyl derivative of bis(4-hydroxyphenyl)sulfone. A partial decomposition of the sulfone groups in PSF during the THM reaction also was noted. The findings also were confirmed by matrix assisted laser desorption mass spectrometric measurements. 

Acetone and phenol can be recovered after the neutralization of the acidic mixture from the cleavage reactor with sodium hydroxide or phenolate solution. The neutralized mixture is then subjected to a series of distillations. Acetone is first distilled, then cumene is recovered, together with a-methylstyrene, which is either purified and marketed or hydrogenated back to cumene and recycled to the oxidation. Phenol is finally distilled with a purity up to 99.99%, suitable for the production of polycarbonate grade bisphenol A and other chemicals and polymers. 

Compound VIII, whose molecular ion peak appears at 228 could have been formed by the loss of the CH2 moiety (m/e = 14) from VII, and/or from the cleavage of a n-propyl moiety from VI. VIII does not appear to possess the isopropy1idene group as evidenced by large differences in the fragmentation patterns of VIII and bisphenol A. Although the structures indicate only one isomer other isomers are possible. 

A disproportionation reaction of the bisphenol A unit (Scheme 5.8d), with consequent polymer chain cleavage, accotmts for fhe formation of pyrolysis compounds with phenyl and isopropenyl end-groups, such as phenol (ion m/z 94, Figure 5.19d) and isopropenyl phenol. 

Linear and cyclic structures of polycarbonates from bisphenol-A, from bisphenol-Z, and from 4,4 -dihydroxydiphenyl-3,3-pentane, were determined by PSD MALDI-TOF experiments. It was foimd that the fragmentation behavior of these polycarbonates depends on the substituents boimd to the central carbon atom of the bisphenol unit. The cleavage of the polymer backbone is suppressed, and the spectra are dominated by the loss of side groups. PSD MALDl spectra of these polycarbonates could be acquired only from Li adduct ions, because the sodium or potassium cationized adduct ions yield only dissociation of the cation from the polymer. ... 

The effect of bisphenol structure on kinetic parameters of their high temperature reaction with terephthaloyl chloride has been evaluated and discussed. " In this field a new preparative process involving the interaction of a pre-formed polyester, a diacid, and bisphenol diacetates in the melt-phase has been described. Kinetic and mechanistic studies have indicated the reaction to occur via the simultaneous cleavage of the pre-formed polyester by the diacid, condensation polymerization of carboxy and bisphenol acetate groups, and equilibration through polyester cleavage by carboxyl polymer ends. 

Y. Ono, K. Terada, K. Mizuma and M. Shibasaki, Cleavage method of bisphe-nols, US Patent 6459004, assigned to Mitsui Chemicals, Inc., October 1,2002. G.R. Paler and M.J. Cipullo, Process for stabilizing a liquid crude Bisphenol A product stream, European Patent 0310925, assigned to General Electric Company, December 4,1989. 

Utilizing McGrath s method", we were able to synthesize the THP-protected disiloxane 5 in high yield. The deprotection of the bisphenol under acid conditions can lead to the predominant cleavage of the phenyl-Si bond, but if done with care, the... 

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