Hydroxy-diphenylmethanes

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. 

NovolakS. Novolak resins are typically cured with 5-15% hexa as the cross-linking agent. The reaction mechanism and reactive intermediates have been studied by classical chemical techniques (3,4) and the results showed that as much as 75% of nitrogen is chemically bound. More recent studies of resin cure (50-53) have made use of TGA, DTA, GC, IR, and NMR (16). They confirm that the cure begins with the formation of benzoxazine (12), progresses through a benzyl amine intermediate, and finally forms (hydroxy)diphenylmethanes (DPM). 

For uniformity with the stmctures given in the Colourindex the ammonium radical (9) is used for the amino-substituted xanthenes and the keto form for the hydroxy derivatives. The xanthene dyes may be classified into two main groups diphenylmethane derivatives, called pyronines, and triphenylmethane derivatives (eg, (4)), which are mainly phthaleins made from phthaUc anhydride condensations. A third much smaller group of rosamines (9-phenylxanthenes) is prepared from substituted ben2aldehydes. The phthaleins may be further subdivided into the following fluoresceins (hydroxy-substituted) rhodamines (amino-substituted), eg, (6) and mixed hydroxy/amino-substituted. 

Although treated as separate classes in the Colour Index, these structural types are closely related and the few diphenylmethane dyes such as auramine (1.28 Cl Basic Yellow 2) are now of little practical interest. Commercial usage of the triarylmethane dyes and pigments has also declined considerably in favour of the major chemical classes. They were formerly noteworthy contributors to the acid, basic, mordant and solvent ranges, primarily in the violet, blue and green sectors. Numerous structural examples are recorded in the Colour Index. The terminal groupings can be amine/quinonimine, as in auramine and crystal violet (1.29 Cl Basic Violet 3), hydroxy/quinone, or both. The aryl nuclei are not always benzenoid (section 6.5). 

The question may arise whether diphenylmethane derivatives—e.g., bis-4-hydroxy-3,5-dimethoxyphenylmethane and diguaiacylmethane, are realistic lignin models. Pertaining to this study, the models are realistic if they occur in lignin in situ or if they are artifacts formed in any of the various alkaline pulping processes. 

A number of different hindered diamines have been investigated as a substitute for MOCA (1). In addition to diamine curing agents, which are used most frequently with elastomers based on polyether polyols and toluene diisocyanate (TDI), prepolymers based on polyether or polyester polyols and 4,4 -diphenylmethane diisocyanate (MDI), can be cured with diols to yield elastomers with similar properties to those of diamine-cured polyester-TDI elastomers. The most common chain extender is butanediol. However, to achieve improved mechanical properties, especially at elevated temperatures, aromatic diols are often used. The most common one is hydroquinone di-(beta-hydroxy-ethyl) ether (HEQ). 

Welch et al., 1969 Cecil et al., 1971). After the discovery of the oestrogen action of o,p -DDT, Bitman and Cecil (1970) established in their comparative investigations that those diphenylmethane and diphenylethane derivatives have an oestrogen action in which at least one of the two p-positions is unsubstituted or carries a hydroxy or a methoxy substituent. A further factor connected with bioactivity is that o,p -DDT has two enantiomeric forms (McBlain et al., 1976 1977). 

Diisocyanates are an important class of chemicals of commercial interest, which are frequently used in the manufacture of indoor materials. such as adhesives, coatings, foams and rubbers (Ulrich, 1989). In some types of particle board, the diisocyanates have replaced formaldehyde. Isocyanates are characterized by the electrophilic -N=C=0 group, which can easily react with molecules containing hydroxy groups, such as water or alcohols. On hydrolysis with water, primary amines are formed, while a reaction with alcohols leads to carbamates (urethanes). Polyurethane (PUR) products are then obtained from a polyaddition of diisocyanate and diol components. Compounds commonly used in industrial surface technology are 4,4 -diphenylmethane diisocyanate (MDI) and hexamethylene diisocyanate (HDI). The diisocyanate monomers are known as respiratory sensitizers and cause irritation of eyes, skin and mucous membrane. Therefore, polyisocyanates such as HDI-biuret and HDI-isocyanurate with a monomer content <0.5 % are used for industrial applications, and isocyanate monomers will not achieve high concentrations in ambient air. Nevertheless, it is desirable to measure even trace emissions from materials in private dwellings. 

A slurry of 550 g. ethyl N-hydroxy-carbamate potassium salt, 642 g. bromo-diphenylmethane, and NaHCOg in di-methylformamide stirred vigorously at 60° during 1.5-2 hrs. until neutral to moist litmus -> 178 g. ethyl N-benz-hydryloxycarbamate. 

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... 

Suitable starting compounds are polyesters from poly(ethylene oxide) and adipic acid, also poly(propylene oxide) or poly(oxytetramethylene) with molecular weights around 2,000, whose hydroxy end groups can be reacted with very reactive diisocyanates such as 1,5-naphthalene diisocyanate, 1,4-phenylene diisocyanate, and diphenylmethane-4,4 -diisocyanate. 

MDI method For determination of 4,4 -diphenylmethane diisocyanate in the atmosphere, 5 litres of air should be drawn through 3 ml of 0-4n hydrochloric acid. After the addition of three drops of a 0-6% (w/v) sodium nitrite solution six drops of 10% (w/v) sulphamic acid should be added and the mixture transferred to a separating funnel containing 2 ml of 1 n sodium hydroxide solution and six drops of a suspension of 0-5 g of 2-hydroxy-3-naphthoic anilide (Brenthol AS) in 50 ml water. This mixture is then shaken and 1 ml of 6n sulphuric acid followed by 3 ml of chloroform are added. This is shaken and the chloroform layer separated off. The colour of this chloroform layer is then compared with standard colour solutions prepared by mixing a solution of cobaltous chloride (as above) with a solution of 32 g anhydrous ferric chloride, 25 ml concentrated hydrochloric acid (SG 20°C 1-18) and 975 ml water. The proportions of these two solutions equivalent to different levels of atmospheric diisocyanate are given in Table 11.3. 

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. 

This limitation is overcome when the elastomer is cast from a mixture consisting of a linear polyester or poly ether, diisocyanate and glycol or diamine. In this process, the hydroxy-terminated polymer (e.g., poly(ethylene adipate) or poly(oxytetramethylene) glycol) is treated with an excess of diisocyanate (e.g., naphthylene 1,5-diisocyanate, tolylene diisocyanate or diphenylmethane 4,4 -diisocyanate). The product is a pre-polymer which is, in effect, a mixture of isocyanate-terminated polymer and unreacted diisocyanate. The pre-polymer is then mixed with either a glycol (e.g., 1,4-butanediol or 1,6-hexanediol) or diamine (which is usually a deactivated amine such as 3,3 -dichloro4,4 -diamino-diphenylmethane (MOCA)). The mixture is poured into a heated mould where it quickly sets. After about 30 mins the casting is removed from the mould and cured at about 110°C for 24 hours. 

In -this paper, we will shortly discuss our approach to prepare hydroxy-terminated MDl/BDO-based urethane oligomers and their 4-diphenylmethane carbamates, 18 and describe in more detail the synthesis of monodisperse hydroxy-terminated oligo(oxy-tetramethylenes), their use for the investigation of the prepolymer formation, and the synthesis of linear PU-elastomers with narrow (monodisperse) soft and/or hard segment length distribution by using the hydroxy-terminated segment precursors. The chemical structures of the model systems studied in this... 

Obtained by heating 4-hydroxy-4 -nitro-diphenylmethane (SM), sulfur and sodium hydroxide in 50% ethanol in a boiling water bath for 7 h (60%) [112]. In this reaction, oxidation of the methylene group to a carbonyl group occurred together... 

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