Alcohol dihydric

Polyhydric alcohols are compounds containing two or more hydroxyl groups in the molecule. The two most important are ethylene glycol HOCHjCHjOH (a dihydric alcohol) and glycerol HOCHjCH(OH)CH. OH (a trihydric alcohol). Ethylene glycol may be obtained by the hydrolysis of ethylene dibromide or ethylene dichloride with dilute aqueous sodium hydroxide or sodium carbonate solution ... 

Dihydric alcohols give normal or cycHc alkoxides. Amino alcohols react similarly (57) ... 

Polyester—any long-chain synthetic polymer composed of at least 85% hy weight of an ester of a dihydric alcohol and terephthalic acid (p—HOOC—C6H4—COOH). 2.2-7.8 E-G G G-F G G 1.38 300... 

Higher alcohols have more than three carbon atoms. Examples are the dihydric alcohol, ethylene glycol used for antifreeze, brake fluids and as derivatives in resins, paints " " osives, and polyester fibers. Reactions with propylene make propylene glycol, a moistening ag foods and tobacco. 

LELOBINE AND LOBININE GROUPS. These include the minor alkaloids of lobelia isolated from factory residues accumulated during the manufacture of lobeline. Their isolation and separation involve complicated processes of fractionation for which the original paper should be consulted. Their inter-relationships (Table A, p. 23 and general formula, I, p. 24) are similar to those among members of the lobeline group, but the effect of the presence of three or more asymmetric carbon atoms is more evident, thus there are already known six forms of the basic dihydric alcohol, lelobaiiidine. 

Oxidation by Chromic Acid. Under mild conditions, e.g., in acetic acid at atmospheric temperature this converts the dihydric alcohol or keto-alcohol bases to diketo-bases, e.g., the lelobanidines, Ci3H2902N, to lelobanines, C13H25O2N. Under more vigorous action the keto-alcohol and the diketo-bases are oxidised to benzoic acid (side-chain, Ph. CO. ), acetic and i iropionic acids (side-chain, C2H5. CO. ) and either scopolinic acid l-methylpiperidine-2 6-dicarboxylic acid (IV)) or methylgranatic acid (l-methylpiperidine-2-carboxylic-6-acetic acid) or both, these being from the methylpiperidine nucleus with residues of the two side-chains. 

Lobinine, CjgHggOgN. First isolated by Wieland, Ishimasa and Koschara who, on the evidence then available, regarded it as 2-phenacyl-l-methyl-7-)3-hydroxypropylhexamethyleneimine, CjgHjjOjN (XXI), which was modified to (XX) in 1989. It furnishes an oxime (B. HCl, m.p. 182°) and a benzoyl derivative (B. HCl, m.p. 146-7°). On reduction by sodium in acetic acid it is converted into the unsaturated dihydric alcohol for which th original name lobinol has been changed to /3-lobinanidine,... 

Dihydric alcohol or glycol (two hydroxyl groups) CH2OHCH2OH... 

Dihydro-2-formyl-2H-pyran, 1 279 Dihydrazides, 13 574, 599 Dihydric alcohols, dispersants, 8 710t Dihydroabietyl alcohol, in eye makeup,... 

The reactions of the simplest dihydric alcohols, the 1 2-glycols, may be illustrated by means of the initial member of the series. 

Because PET has a melting point Tm of 240 C, it is difficult to mold. The difficulty in processing and the low ductility of PET have been overcome by the production of terephthalic acid esters with higher-molecular-weight dihydric alcohols, such as butylene glycol. 

Otto Bayer produced PUs in the 1940 s by reacting diisocyanates, such as tolyl diisocyanate, with dihydric alcohols, such as ethylene glycol. In another experiment he added a diisocyanate to cure synthetic rubber (SR) containing hydroxyl groups. The rubber was cured (vulcanized), but it stuck to the mold. Variations of products from these two experiments are now used as two-component adhesives for bonding footwear and automotive plastic parts. 

Alicyclic hydroxylation. Hydroxylation of saturated rings yields monohydric and dihydric alcohols. For instance, cyclohexane is metabolized to cyclohexanol, which is further hydroxylated to frcms-cyclohexane-l,2-diol (Fig. 4.11). With mixed alicyclic/aromatic, saturated and unsaturated systems, alicyclic hydroxylation appears to predominate, as shown for the compound tetralin (Fig. 4.12). 

Long chain polymers of ethylene-oxide with dihydric alcohols HOCHj (CH2 0CH2 )nCH2 OH Carbowaxes Carbide and Carbon Chem Co... 

GLYCOL. A dihydric alcohol (i.e.. a compound conlaining two alcoholic hydroxy] groups). The chemical properties are represented by those of the simplest members of the class, ethylene glycol, 1,2-ethanediol. CH-OH CHjOH. which is a colorless, viscous liquid, of sweetish taste. Odorless, boiling point I97°C. miscible in all proportions with water or alcohol, slightly soluble in ether. Like ethyl alcohol, ethylene glycol is often called by the class name. 

POLYESTER FIBERS. The principal characteristics of these fibers are described in the endy on Fibers. Polyester fibers are defined as synthetic fibers containing at least 80% of a long-chain polymer compound of an ester of a dihydric alcohol and terephthalic acid. T he first polyester fiber to be commercialized was prepared from the ester in which the dihydric alcohol was ethylene glycol this fiber is the material used in the largest quantity bv the textile industry. For some other commercial uses, the ester 1,4-dimethyldicyclohexyl terephthalate is also used... 

Long-cham polymers of ethylene oxide combined with a dihydric alcohol, namely polyoxyethylene glycol, ( Carbo-wax"). 

It is worth noting that if the aldol condensation takes place in the presence of magnesium amalgam, the aldehydic group is simultaneously reduced and a 1 3-dihydric alcohol is formed. 

Maleic and phthalic anhydrides and fumaric acid are mainly used for polyester resin synthesis. However, dihydric alcohols such as ethylene and propylene glycols, diethylene, dipropylene, triethylene and neopentyl glycols, and hydrided or oxypropylened diphenylolpropane are also used.5 7 Different combinations of dibasic acids with diols allow us to vary the composition and properties of the resulting polyester resins over a wide range. 

The purity of lanolin and standard tests have been described in the European Pharmacopoeia (EP), in The United States Pharmacopoeia (USP), and according to other national standards.13,14 Lanolin is a semisolid with a melting point of approximately 40 6°C and has a molecular weight in the range of 790 to 880 Da. Lanolin is a complex and variable mixture of mainly esters, diesters, hydroxy esters (87.0-93.5%, w/w),7 8 15 lanolin alcohols (6.0-12.5%, w/w), lanolin acids (<0.5%, w/w), and lanolin hydrocarbons (<1.0%, w/w). The latter are also called paraffins and petrolatum by the EP and USP, respectively.13,14 16-18 Approximately 40% of the esters are a-hydroxy esters. Due to the extremely complex nature of lanolin, the true number of different esters present is unknown. Barnett calculated the theoretical number of monoester combinations from random combinations of 69 aliphatic lanolin alcohols, 6 sterols, and 138 saturated lanolin acids to total 10,350.8 This is most probably an underestimate of the total number of esters, as dibasic acids and dihydric alcohols also occur naturally in lanolin.19 Further combinations of cyclic mono- and di-esters may be formed by dehydration and from inter- and intra-esterification due to heating during the manufacturing process.7 8... 

The study was further extended to investigate the effect of a range of dihydric alcohols (ethylene glycol, 1,3-propanediol, 1,2-butanediol and 1,3-butanediol). The addition of the dihydric alcohol improved the smoothness and color of the deposits and also increased the cathodic current efficiency at high current density. Of the four dihydric alcohols, ethylene glycol gave the best results. 

The GC separation of dihydric alcohols of natural origin may be carried out after their conversion into alkyl boronates. Methaneboronates of ceramides [44] were prepared by treatment with methaneboronic acid in pyridine solution. They offer excellent GC properties on stationary phases of the OV-1 and SE-30 types and are particularly suitable for GC-MS. 

Glycol. Ethylene glycol, HO—CH2—CH2—OH also a general term for dihydric alcohols, that is, dihydroxy derivatives of the aliphatic hydrocarbons. 

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