Dimethanol

Ferrocene-1,1,-dimethanol [ 1291-48-1 ] M 246.1, m 107-108°. Obtained from the diacid with LiAlH4 reduction and recrystd from Et20-pet ether. [J Am Chem Soc 82 4111 7960.]... 

In 1975, Weber and Vogtle showed that open-chained polyethers, 2,6-pyridine-dimethanol, and ortho-xylene derivatives terminated in an 8-quinolinyl group could form stable, 1 1, crystalline complexes with a variety of metal salts. The podands were prepared from 8-hydroxyquinoline and the corresponding dihalides. A typical example is shown in Eq. (7.10). 

Several titanium(IV) complexes are efficient and reliable Lewis acid catalysts and they have been applied to numerous reactions, especially in combination with the so-called TADDOL (a, a,a, a -tetraaryl-l,3-dioxolane-4,5-dimethanol) (22) ligands [53-55]. In the first study on normal electron-demand 1,3-dipolar cycloaddition reactions between nitrones and alkenes, which appeared in 1994, the catalytic reaction of a series of chiral TiCl2-TADDOLates on the reaction of nitrones 1 with al-kenoyloxazolidinones 19 was developed (Scheme 6.18) [56]. These substrates have turned out be the model system of choice for most studies on metal-catalyzed normal electron-demand 1,3-dipolar cycloaddition reactions of nitrones as it will appear from this chapter. When 10 mol% of the catalyst 23a was applied in the reaction depicted in Scheme 6.18 the reaction proceeded to give a yield of up to 94% ee after 20 h. The reaction led primarily to exo-21 and in the best case an endo/ exo ratio of 10 90 was obtained. The chiral information of the catalyst was transferred with a fair efficiency to the substrates as up to 60% ee of one of the isomers of exo3 was obtained [56]. 

Trimethoxybenzoic acid Thionyl chloride Pyridine-2,6-dimethanol... 

A solution comprising 3,24 kg (23.3 mols) of pyridine-2,6-dimethanol in 35 liters of pure pyridine was added to the residue and the mass was heated to 80°C for 2 /a hours. The reaction mass became brown in color. The chlorhydrate of pyridine so formed was cooled and crystallized. The resulting reaction mass was then poured into water. The precipitate obtained was filtered, repeatedly rinsed with water, and dissolved in 400 liters of methanol. The resulting solution was filtered with activated charcoal. From this filtration 50 liters of methanol were distilled at normal pressure and then crystallized. 8.35 kg (15.8 mols) of pyridine-2,6-dimethanol trimethoxybenzoate were obtained, which represented a yield of 68%. 

The principal solvolysis reactions for PET are methanolysis with dimethyl terephthalate and ethylene glycol as products, glycolysis with a mixture of polyols and BHET as products, and hydrolysis to form terephthalic acid and ethylene glycol. The preferred route is methanolysis because the DMT is easily purified by distillation for subsequent repolymerization. However, because PET bottles are copolyesters, the products of the methanolysis of postconsumer PET are often a mixture of glycols, alcohols, and phthalate derivatives. The separation and purification of the various products make methanolysis a cosdy process. In addition to the major product DMT, methanol, ethylene glycol, diethylene glycol, and 1,4-cyclohexane dimethanol have to be recovered to make the process economical.1... 

CniHifiN205 138681-67-1) see Zafirlukast a -(nitromethyl)-3-(phenylmethoxy)-2,6-pyridine-dimethanol... 

Synonym(s) 6,7,8,9,10,10-Hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzo(e)-dioxathiepin-3-oxide Endosulfan technical 5-Norbornene-2,3-dimethanol-1,4,5,6,7,7-hexachlorocyclic sulfite HSDB 1999 IRIS 2000 Budavari 1996... 

FIGURE 2 Glass transition temperature of a polymer prepared from 3,9- bis ( ethylidene- 2,4,8,10-tetraoxaspiro [ 5,5 ] undecane ) and mixtures of trans-cyclohexane dimethanol and 1,6-hexanediol as a function of mol% 1,6-hexanediol. (From Ref. 13.)... 

FIGURE 8 Cumulative release of methylene blue (o), [1,4 - 14c] succinic acid (a), and polymer weight loss ( ) from polymer discs prepared from 3,9-bis(ethylidene-2,4,8,10-tetraoxaspiro[5,5Jundecane) and a 50 50 mole ratio of trans - cyclohexane dimethanol and 1,6-hexanediol at pH 7.4 and 37°C. Polymer contains 0.1 wt% [1,4 — [succinic anhydride and 0.3 wt% methylene blue. (From Ref. 

FIGURE 13 Cumulative release of -nitroacetanilide (PNAC) from polyester discs prepai ed from 3,9-bis(ethylidene-2,4,8,10-tetraoxas-piro[5,5]undecane) and a 60 10 30 mole ratio of trans-cyclohexane dimethanol, 1,6-hexanediol, and triethylene glycol at pH 7.4 and 37 C. PNAC content 2 wt% (o) 0 mol%, ( ) 0.25 mol%, ( ) 0.50 mol% 9,10-dihydroxystearic acid. (From Ref. 23.)... 

FIGURE 25 HPLC chromatograms of polymer samples hydrolyzed to cleave all ortho ester bonds. Samples were prepared at either 130, 145, or leO C. Polymer prepared from 3,9-bis(ethylidene-2,4,8,10-tetraoxaspiro)5,5]undecane) and a 25 75 mole ratio of trans-cyclohexane dimethanol and 1,6-hexanediol and contained 3 wt% phthalic anhydride and 7.5 wt% cyclobenzaprine hydrochloride (CBP). 

The a,a,a,a-tetraaryl-l,3-dioxolane-4,5-dimethanol (TADDOL) chiral ligands have also been the basis of enantioselective catalysis of the D-A reaction. In a study using 2-methoxy-6-methylquinone as the dienophile, evidence was found that the chloride-ligated form of the catalysts was more active than the dimeric oxy-bridged form.117... 

The starting material was trans-cyclopropane-1,2-dimethanol. The contiguous cyclopropane units were added by two iterative sequences of oxidation-Wadsworth-Emmons reduction-cyclopropanation. 

Theobromine was determined by GC in various foods (bitter chocolate, milk chocolate, chocolate cake, cocoa powder, chocolate milk), and results are given in graphs and tables.27 Homogenized samples were boiled in alkaline aqueous media, then fat was extracted with n-hexane. The aqueous layer was acidified with diluted HC1 and NaCl was added. Theobromine was extracted from this treated aqueous solution with dichloromethane and the extract was evaporated to dryness. The residue was redissolved in dichloromethane containing an internal standard. GC analysis was performed on a column packed with 1% cyclohexane dimethanol succinate on Gaschrom Q, with FID. Average recoveries were 99 to 101%, coefficient of variation was less than 3% and the limit of detection for theobromine in foods was about 0.005%. 

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