3.4- Methylene-2,5-dimethylphenol

TABLE 7.7 Percent Yield of Methylene and Ether Linkages of 2-Hydroxylmethyl-4,6-Dimethylphenol Self-reaction, 1 1 with 2,4-Xylenol, and 1 1 with 2,6-Xylenol... 

Carbon tetrachloride. Chloroform, 2-Chlorophenol, Cyclohexanol, Cyclopentene, 1,1-Dichloroethylene, irans-l, 2-Dichloroethylene, IV.yV-Dimethylaniline, lV,lV-Dimethylformamide, 2,4-Dimethylphenol, 2,4-Dinitrotoluene, 1,4-Dioxane, 1,2-Diphenylhydrazine, Ethyl formate. Formaldehyde, Glycine, Methanol, Methylene chloride. Methyl formate, 2-Methvlphenol. Monuron, 4-Nitrophenol, Oxalic acid, Parathion, Pentachlorophenol, Phenol, l idine. Styrene, Trichloroethylene, Vinyl chloride Formylacetic acid, see cis-l,3-Dichloropropylene, irans-1,3-Dichloropropylene IV-Formylcarbamate of 1-naphthol, see Carbaryl Formyl chloride, see Chloroethane, Chloroform, sym-Dichloromethyl ether, ds-1,3-Dichloropropylene, irans-ES-Dichloropropylene, Methyl chloride. Methylene chloride. Trichloroethylene, Vinyl chloride lV-Formyl-4-chloro-o-toluidine, see Chlornhenamidine. 

Solubility in Methylene Chloride. The methods described above can show the presence of blocks of DMP and blocks of DPP units, but they do not distinguish between block copolymers and blends of homopolymers. Gel permeation chromatograms of the copolymers are sharp and symmetrical, indicating that they are indeed copolymers rather than blends, but this alone is not conclusive as blends of the homopolymers do not produce binodal or badly skewed curves under the conditions used unless the two polymers differ considerably in molecular weight. A partial answer to this question is provided by the solubility behavior in methylene chloride. Dimethylphenol homopolymer dissolves readily in methylene chloride but precipitates quantitatively on standing for a short... 

Twenty percent solutions in methylene chloride of the two copolymers prepared by Procedures 1 and 2 were stable indefinitely, showing that no significant amount of dimethylphenol homopolymer was present and that the DMP blocks must be in the form of a block copolymer. Separate experiments using blends of DMP homopolymers with random copolymers or with DPP homopolymer showed that DMP homopolymer, even of very low molecular weight (DP 15), could be detected easily if present to the extent of 5% of the total polymer. 

Aqueous samples are extracted with methylene chloride. If the sample is not clean or if the presence of organic interference is suspected, a solvent wash should be performed. For this, the pH of the sample is adjusted to 12 or greater with NaOH solution. The sample solution made basic is then shaken with methylene chloride. Organic contaminants of basic nature and most neutral substances partition into the methylene chloride phase, leaving phenols and other acidic compounds in the aqueous phase. The solvent layer is discarded. The pH of the aqueous phase is now adjusted to 2 or below with H2S04, after which the acidic solution is repeatedly extracted with methylene chloride. Phenols and other organic compounds of acidic nature partition into the methylene chloride phase. The methylene chloride extract is then concentrated and exchanged into 2-propanol for GC analysis. For clean samples, abasic solvent wash is not necessary however, the sample should be acidified before extraction. It may be noted that basic solvent wash may cause reduced recovery of phenol and 2,4-dimethylphenol. 

Table III. Chemical Shift Values of Methylene and Methyl Protons of Benzyl Derivatives of 2,6-Dimethylphenol (13)...

The kinetic measurements were made in CS2 solution at 70°C in sealed NMR sample tubes. After completion of the prescribed reaction period, each sample tube was cooled quickly to room temperature and transferred to the NMR spectrometer for recording of the spectra. When a solution of 4-benzyl-2,6-dimethylphenol and BF3 (mole ratio 4.5/1.0) was used, the absorption under the methylene peak (3) at 3.80 ppm and the methylene peak (2) at 1.95 ppm increased from an initial value of zero, as the reaction advanced, showing the formation of 3,4-dibenzyl-... 

In contrast to the-self reaction of 27, the reaction of 27 with one and two molar equivalents of 2,4-dimethylphenol (21) gave three products (Scheme 16) the ether (28), the methylene compound (26) and a phenoxy compound (29). 

The behaviour of 2-hydroxymethyl-4,6-dimethylphenol (27) in the presence of 2,6-dimethylphenol (23) was virtually indistinguishable from the self-reaction of 2-hydroxymethyl-4,6-dimethylphenol thus the rates of formation of ether and methylene compounds are similar. No significant quantities of ortho—para linked methylene compound were generated over the timescale studied. A small quantity of the phenoxy derivative 30 was isolated. 

Three novel model compounds, bis(2-hydroxy-4,6-dimethylphenyl)methane (46), (2-hydroxy-4,6-dimethylphenyl-4 -hydroxy-2, 6 -dimethylphenyl)methane (47) and bis(4-hydroxy-2,6-dimethylphenyl)methane (48), were synthesized from 3,5-dunethylphenol. These were used to show that a resole-type resin formed from 3,5-dimethylphenol had a highly condensed, predominately linear structure, linked by ortho-ortho and ortho-para methylene bridges. This is quite unlike the behaviour of phenol-derived resole resins. 

It was concluded at the formation of a xanthene is a key step in the graphitization of 3,5-dimethylphenol resins. Xanthene formation is an efficient way of removing heteroatoms. This step would not be possible if the 3,5-dimethylphenol resin was not significantly ortho-ortho linked. However, the ortho-ortho methylene orientation, though essential, is not the only influencing factor. The methyl groups in the 3- and 5-positions also influence the xanthene formation process, as this reaction was not detectable in bis(2-hydroxyphenyl)methane under comparable conditions. 

Dimethylphenol was chosen as the reagent for deprotection because the OT z-positions on the aromatic ring are blocked and hence prevent seven-membered ring formation and promote the removal of methylene bridges <2005JOC10381>. 

Preparation by acyladon of 2,6-dimethylphenol with m-(tri-chloromethyl)phenyl m-(trichlo-romethyl)benzoate in methylene chloride in the presence of aluminium chloride at 0-5° over 1 h, then at r.L for 1 h, followed by alkaline hydrolysis of the resulting keto ester [325] (Japanese patent). 

Polymer II (a sample with [n] 0.35 dl/g) was used as a phenol for copolymerization with 2,6-dimethylphenol. The physical properties of the product (intrinsic viscosities as high as 0.68 dl/g no fractionation of VIII during methylene chloride complex-ation l no long range nmr effects) suggested a block copolymer structure for the product. Since it is likely that polymer II did not redistribute under the mild conditions of polymerization (Table I shows little equilibration with monomer even at 80 ), polymer II was functioning as a monofunctional consonant which did not readily co-equilibrate with the oth r oligomers. Polymer II can be viewed as a chain stopper for reaction (4) and the product can be represented by structure XIII. Colorless, hazy... 

Xylenol. Xylenols jdeld methylene bis- derh atives in much the same lanner as the isomeric cresols. In the ease of 3,5-dimethylphenol, in fhich none of the active positions are blocked methyl gioups, Morgan succeeded in prepai ing all thi-ee possible isomeric diphenyhnethanes by reaction with formaldehyde luader acidic conditions. 

Na ithols. Beta-naphtbol resembles 2,6-dimethylphenol in that it is readily converted to a methylene bLs derivative under alkaline conditions. 

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