Ethylene-1,2-diols

In rats, i.v. administration of benzylpenicil-lin-CDS with an ethylene 1,2-diol spacer gave an AUC-based brain-exposure enhancement factor for benzylpenicillin of around 11 (Table... 

From the several coupling possibilities investigated, diesters of methylene diol and ethylene 1,2-diol proved worthy of further investigation, but ester-amide combinations did not prove successful. Consequently, the diesters have also been investigated in rabbits and dogs (297). 

Pyrolysis process for poly(2-hydroxyethyl methacrylate) occurs similarly to that for other methacrylic acid esters. The formation of 2-methyl-2-propenoic acid 2-hydroxyethyl ester, the monomer, shows that unzipping is a significant part of the process. Some other compounds in the pyrolysate also are generated from the polymer cleavage, such compounds including 2-methyl-2-propenoic acid ethenyl ester, propanoic acid, 2-methyl-2-propenoic acid, ethanol, etc. On the other hand, some compounds are not expected in the pyrolysate and they can be impurities or additives. Examples of such compounds are the hydrocarbons (undecene, dodecane, 1-dodecene, etc.), the esters of ethylene diol and the free 1,2-ethandiol, etc. The initiator AIBN and its decomposition products 2-methyl-2-propenenitrile and 2-methylpropanenitrile identified in the pyrolysate show that the polymer was obtained using AIBN as initiator. 

Corey and Wat17 found that the method of forming cycloolefins from allylic dihalides and nickel carbonyl provides an unusually efficient route for the formation of large rings. Because it leads to cyclic 1,5-dienes, it makes available a variety of cyclic structures not obtainable in a practical way via the acyloin synthesis. Diacetylenic diols (10) were converted by selective reduction into the corresponding cis.cis- and owu,/ra -ethylenic diols followed by reaction with PBr3 to form the diallylic dibromides (12), which were then cyclized with nickel carbonyl. 

Another exemple of application in the field of agrochemicals can be found in the synthesis of ethylenic diol 25 (19)... 

We have already seen how different types of catalysts can be used to arrest the hydrogenation of a triple bond at the double-bond stage. A solvent or additive can also accomplish this by competitive chemisorption on the catalyst. An example (reaction 6.42) is the hydrogenation of dehydrolinalyl acetate (46) to linalyl acetate (47), a perfumery chemical, without further hydrogenation to the unwanted dihydrolinalyl acetate (48). Compound (48) should be present in less than 2% to preserve the perfumery quality of (47). This can be accomplished by using Pd/C as catalyst with pyridine as the additive or solvent (Gilbert and Mercier, 1993). A similar application can be found in the synthesis of ethylenic diol (Baillard et al., 1988) used in agrochemicals. 

Melt polycondensation is the most used procedure for the preparation of polyesters such as PBSu or PESu from butylene or ethylene diols and dicar-boxyllc acids. Poly(propylene alkylanedicarboxylate) polyesters can be also prepared by the two-stage melt polycondensation method (esterification and polycondensation) using proper amounts of aliphatic acids and 1,3-PD in a glass batch reactor using a procedure described in detail in Ref. [9]. The esterification reaction progress is monitored by measuring the amount of water produced as a by-product and removed by distillation. Other reaction conditions are included in Scheme 4.4. 

A carboxyl-terminated unsaturated polyester was esterified with poly(oxy-ethylene) diols [70]. Using poly(oxyethylene) diol with a munber average molecular weight of 2000, partly crystalline block copolymers were obtained. The unsaturated block copolyether ester contained predominantly one terminal polyether group per molecule. Block unsaturated copolyetheresters with shorter poly(oxyethylene) terminal groups of M = 350 and 550 were also obtained. The effect of the composition of those UPRs on the mechanical and thermal properties was investigated [70]. The block copolyetherester with Mn = 2000 can be dissolved in styrene monomer, thus forming a UPR with acceptable viscosity at as little as 20% styrene. 

Sodium me/aperiodate (NalO ) in cold aqueous solution readily oxidises 1,2-diols with splitting of the molecule and the consequent formation of aldehydes or ketones thus ethylene glycol gives formaldehyde and pinacol gives acetone. In the case of a 1,2,3-triol, the central carbon atom of the triol... 

Polymerisation of a diol with a dicarboxybe acid is exemplified by the production of a polyester from ethylene glycol and terephthabc acid either by direct esterification or by a catalysed ester-interchange reaction. The resulting polyester (Terylene) is used for the manufacture of fibres and fabrics, and has high tensile strength and resibency its structure is probably ... 

It is essential to apply both tests, since some symmetrically substituted ethylenic compounds (e.g., ilbene C4H5CH=CHCjHj) react slowly under tbe conditions of the bromine test. With dilute permanganate solution the double bond is readily attacked, probably through the intermediate formation of a cis diol ... 

Ethylene glycol and propylene glycol are common names for these two diols and are acceptable lUPAC names Aside from these two compounds the lUPAC system does not use the word glycol for naming diols... 

Diols that bear two hydroxyl groups m a 1 2 or 1 3 relationship to each other yield cyclic acetals on reaction with either aldehydes or ketones The five membered cyclic acetals derived from ethylene glycol (12 ethanediol) are the most commonly encoun tered examples Often the position of equilibrium is made more favorable by removing the water formed m the reaction by azeotropic distillation with benzene or toluene... 

Diol Components. Ethylene glycol (ethane 1,2-diol) is made from ethylene by direct air oxidation to ethylene oxide and ring opening with water to give 1,2-diol (40) (see Glycols). Butane-1,4-diol is stiU made by the Reppe process acetylene reacts with formaldehyde in the presence of catalyst to give 2-butyne-l,4-diol which is hydrogenated to butanediol (see Acetylene-DERIVED chemicals). The ethynylation step depends on a special cuprous... 

Poly(propylene oxide) [25322-69-4] may be abbreviated PPO and copolymers of PO and ethylene oxide (EO) are referred to as EOPO. Diol poly(propylene oxide) is commonly referred to by the common name poly(propylene glycol) (PPG). Propylene oxide [75-56-9] and poly(propylene oxide) and its copolymers, with ethylene oxide, have by far the largest volume and importance in the polyurethane (PUR) and surfactant industry compared to all other polyepoxides. Articles reviewing propylene oxide (1), poly(propylene oxide) (2—4), other poly(aIkylene oxides) (4), and polyurethanes (5—7) are cited to lead the interested reader to additional detail not in the scope of this article. 

Solubility. PPO polyols with a molecular weight below 700 are water soluble. The triol is slightly more water soluble than the diol. The solubihty in water decreases with increasing temperature. This inverse solubiUty causes a cloud point which is important in characteri2ing copolymers of propylene oxide and ethylene oxide. 

Diols, such as ethylene glycol, are usually not added during the alcoholysis step because their monoesters have only one remaining hydroxyl group, and would function as chain stoppers, thus severely limiting their utihty in the stmcture design of the resin molecules. 

Silver carbonate, alone or on CeHte, has been used as a catalyst for the oxidation of methyl esters of D-fmctose (63), ethylene (64), propylene (65), trioses (66), and a-diols (67). The mechanism of the catalysis of alcohol oxidation by silver carbonate on CeHte has been studied (68). 

Glycol Titanates. Primary diols (HOGOH), such as ethylene glycol and 1,3-propanediol, react by alkoxide interchange at both ends, yielding insoluble, white soflds that are polymeric in nature (18,61—63) ... 

The addition of one mole of a diol, such as ethylene glycol, 1,2-propanediol, or 1,4-butanediol, to bis-acetylacetone titanate complexes gives a complex that is stable on dilution with water and that can be used in aqueous printing inks (509). An excellent review of the use of organic titanates in printing inks is available (510). 

Polyurethane foams are formed by reaction with glycerol with poly(propylene oxide), sometimes capped with poly(ethylene oxide) groups with a reaction product of trimethylolpropane and propylene oxide or with other appropriate polyols. A typical reaction sequence is shown below, in which HO—R—OH represents the diol. If a triol is used, a cross-linked product is obtained. 

Polyester and polyether diols are used with MDI in the manufacture of thermoplastic polyurethane elastomers (TPU). The polyester diols are obtained from adipic acid and diols, such as ethylene glycol, 1,4-butanediol, or 1,6-hexanediol. The preferred molecular weights are 1,000 to 2,000, and low acid numbers are essential to ensure optimal hydrolytic stabihty. Also, caprolactone-derived diols and polycarbonate diols are used. Polyether diols are... 

Polyesters. Polyesters (qv) are widely used as the matrix for conventional composites. Two resins of particular importance because of the large amounts used are (poly(ethylene terephthalate) [25038-59-9] (PET) and poly(butylene terephthalate) [24968-12-5] (PBT). Although polyesters can be made from diacids and diols by direct condensation. 

Most polyesters (qv) are based on phthalates. They are referred to as aromatic-aHphatic or aromatic according to the copolymerized diol. Thus poly(ethylene terephthalate) [25038-59-9] (PET), poly(butyelene terephthalate) [24968-12-5] (PBT), and related polymers are termed aromatic-aHphatic polyester resins, whereas poly(bisphenol A phthalate)s are called aromatic polyester resins or polyarylates PET and PBT resins are the largest volume aromatic-aHphatic products. Other aromatic-aHphatic polyesters (65) include Eastman Kodak s Kodar resin, which is a PET resin modified with isophthalate and dimethylolcyclohexane. Polyarylate resins are lower volume specialty resins for high temperature (HDT) end uses (see HeaT-RESISTANT POLYAffiRS). 

Decan-l,10-diol [112-47-0] M 174.3, m 72.5-74 . Crystd from dry ethylene dichloride. 

The polyols used are of three types polyether, polyester, and polybutadiene. The polyether diols range from 400 to about 10,000 g/mol. The most common polyethers are based on ethylene oxide, propylene oxide, and tetrahydrofuran or their copolymers. The ether link provides low temperature flexibility and low viscosity. Ethylene oxide is the most hydrophilic and thus can increase the rate of ingress of water and consequently the cure rate. However, it will crystallize slowly above about 600 g/mol. Propylene oxide is hydrophobic due to hindered access to the ether link, but still provides high permeability to small molecules like water. Tetrahydrofuran is between these two in hydrophobicity, but somewhat more expensive. Propylene oxide based diols are the most common. 

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