Dihydroxy-diphenylmethane

Diglycidyl ether of bisphenol A (DGEBA, MW 340 Da) and 4,4 -dihydroxy-diphenylmethane (DHDPM, MW 200 Da) were analysed by SEC-MALS [784]. DGEBA and DHDPM are the basic oligomers of epoxy resins and phenol-formaldehyde condensates, respectively, which are widely used in the electronic and automotive industries. Excellent reproducibility ( 1 %) and good accuracy (better than 10%) were observed. SEC has also been used for the determination of mineral oil in extended elastomers [785] and in PS [178]. With heptane containing 0.05% isopropanol as the mobile phase, mineral oil is completely unretained and elutes before the solvent via SEC all other components in a PS extract are retained on silica and elute after the solvent peak. 

Dichloro-2,2 -dihydroxy diphenylmethane, m243 1,1-Dichlorodimethyl ether, d237 Dichlorohydrin, d264... 

G NMR Spectra. G spectra were obtained with a Varian Associates FT-80 spectrometer at 20,000 MHz under several conditions. Samples from 10-, 35-, 60-, and 120-min reaction times were examined in THF-dg in the presence of O.IM fm-(acetylacetonate)-chromium(IH) (Gr(acac)3) using 90° pulses and 1.4-sec recycle times with gated proton decoupling for Nuclear Overhauser enhancement (NOE) suppression (6). These parameters gave quantitative results for all carbons of 2,2-dihydroxy diphenylmethane as well as pyrene, whose innermost carbons (10b and 10c) exhibit Tj values of greater than 200 sec (7), Ladner has reported a 14.0-sec delay and a 0.3-sec acquisition time with 0.04M Gr(acac)3 (8) using a 35°... 

Dibromo-4-cyanophenol. See Bromoxynil 3,3-Dibromo-5,5-dichloro-2,2-dihydroxy-diphenylmethane 6,6-Dibromo-4,4-dichloro-2,2 -methylenediphenol. See Bromochlorophene 1,2-Dibromo-2,4-dicyanobutane. See Methyldibromo glutaronitrile Dibromodifluoromethane CAS 75-61-6 EINECS/ELINCS 200-885-5 UN 1941 (DOT)... 

In the course of the previous work we have prepared compounds for comparative purposes, one of which has been reported by Gierer. He and his co-workers 15) synthesized an unsymmetrical diphenylmethane by acid-catalyzed condensation of syringyl alcohol and 2-methoxy-4-methyl-phenol and assumed substitution in the 6-position of the guaiacol nucleus. We repeated this synthesis and prepared an isomeric material by base-catalyzed condensation of the same starting materials. Our interpretation of the modes of synthesis and the NMR spectra of the two compounds is that Gierer s compound most probably is 3, 4-dihydroxy-6 -methyl-3,4, 5-trimethoxydiphenylmethane and that the compound prepared under basic conditions is 2, 4-dihydroxy-5 -methyl-3,3, 5-trimethoxydiphenylmethane, the structure claimed by Gierer. We do not, however, have unequivocal structural evidence and our data are summarized under Experimental. 

In the presenee of coneentrated sulfuric acid, chromotropic acid (1,8-dihydroxy-naphthalene-3,6-disulfonic acid) reacts with formaldehyde to give a red-violet hydroxy-diphenylmethane derivative, as shown in Eq. (2) (Eegriwe, 1937), which is soluble in acid. In the second step of the reaction, a violet quinoid oxidation product is formed with atmospheric oxygen. The concentrated sulfuric acid behaves as a catalyst for dehydration and oxidation. The absorption maximum at 580 nm is used for colorimetric detection. 

Dihydroxy-3-(2H-benzotriazol-2-yl)-5-(1,3,3-tetramethylbutyl)-2 -n-octoxy-5 -benzoyl] diphenylmethane CAS 162245-07-0... 

Methanol, sodium salt. See Sodium methylate 2-Methanol tetrahydropyran. See Tetrahydropyran-2-methanol Methanone, [5-[[3-(2H-benzotriazol-2-yl)-2-hydroxy-5-(1,1,3,3- tetramethylbutyl) phenyl] methyl]-2-hydroxy-4-(octyloxy) phenyl) phenyl-. See [2,4 -Dihydroxy-3-(2H-benzotriazol-2-yl)-5-( 1,3,3-tetramethyl butyl)-2 -n-octoxy-5 benzoyl] diphenylmethane Methanone, (1,1 -biphenyl)-4-yl phenyl)-. Seep-Phenylbenzophenone... 

When a rigid and bulky diol is used as the chain extender, harder elastomers of higher modulus are produced. It can be seen in Table 3.14 that a toluene diisocyanate-based composition (A) from the bulky diol 1,4-dihydroxy-1,2,3,4-tetrahydronaphthalene is inferior in tensile properties to the diphenylmethane diisocyanate-based material (C), although composition (A) is superior to the elastomer from 1,4-butane diol (B). A similar situation can be seen with composition (E), where a,a -dihydroxyxylene was used, compared with composition (D) based on 1,4-butane diol. 

Despite the similar chemical nature, there is no evidence for cross-reactivity between phenol-formaldehyde resin and PTBP-FR (Geldof et al. 1989). Some authors have attributed test reactions to PTBP-FR to free formaldehyde however, most patients are actually not allergic to formaldehyde. Schubert and Agatha (1979) performed patch-test studies with the chroma-tographically extracted ingredients of commercially available PTBP-FR. They found two linear condensates named 2-hydroxy-5-tert.-butylbenzylalcohol and 2,2 -dihydroxy-3,3-di-(2-hydroxy-5-tertiary butyl)-benzyl-5,5-ditertiary butyl-diphenylmethan to be the real allergens. 

Zinke and his co-workers have postulated that the main reaction involved is the breakdown of ether links to give methylene links with loss of formaldehyde. This suggestion is supported by the isolation of diphenylmethane derivatives from the reaction mixtures obtained by heating dibenzyl ethers, e.g., 2,2 -dihydroxy-3,5,3, 5 -tetramethyldibenzyl ether ... 

In a typical manufacturing process a prepolymer is first produced by reacting a linear terminal dihydroxy polyester or polyether of molecular weight 800-2500 with an excess of diisocyanate (usually 4,4 -diphenylmethane diisocyanate) at about 80-120 C. The product at this stage is an isocyanate-terminated prepolymer plus free (unreacted) isocyanate. This blend is then reacted with a chain extender, usually a glycol such as 1,4-butane glycol, to give a chain with a hard... 

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