A Diols

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 ... 

Analysis The cychc ether is obviously made from a diol, and that gives us a 1,2-dioxygenated skeleton of the right kind ... 

A is simply made, but the synthesis of B is not straightforward and it turns out that it is best done not fiom a mono-alcohol, but fiom a diol ... 

Much of the chemistry of diols—compounds that bear two hydroxyl groups—is analo gous to that of alcohols Diols may be prepared for example from compounds that con tain two carbonyl groups using the same reducing agents employed m the preparation of alcohols The following example shows the conversion of a dialdehyde to a diol by... 

A diol (CgHig02) does not react with periodic acid Its H NMR spectrum contains three singlets at 8 1 2 (12 protons) 1 6 (4 protons) and 2 0 (2 protons) What is the structure of this dioH... 

Polyesters are a second class of condensation polymers and the principles behind their synthesis parallel those of polyamides Ester formation between the functional groups of a dicarboxylic acid and a diol... 

Uses. Butanediol is used to manufacture the insecticide Endosulfan, other agricultural chemicals, and pyridoxine (vitamin B ) (see Vitamins) (116). Small amounts are consumed as a diol by the polymer industry. 

Albright Wilson s Vircol 82 is a diol mixture obtained by the reaction of propylene oxide and dibutyl acid pyrophosphate (112). The neutral Hquid has an OH number of 205 mg KOH/g and contains 11.3% phosphoms corresponding to the formula shown where x y = 3.4. The product is a mixture of isomers. 

Other minor raw materials are used for specific needs. Eumaric acid [110-17-8] the geometric isomer of maleic acid, is selected to maximize thermal or corrosion performance and is the sole acid esterified with bisphenol A diol derivatives to obtain optimum polymer performance. CycloaUphatics such as hydrogenated bisphenol A (HBPA) and cyclohexanedimethanol (CHDM) are used in selective formulations for electrical apphcations. TetrahydrophthaUc anhydride [85-43-8] (THPA) can be used to improve resiUence and impart useful air-drying properties to polyester resins intended for coating or lining apphcations. 

The concept of functionaUty and its relationship to polymer formation was first advanced by Carothers (15). Flory (16) gready expanded the theoretical consideration and mathematical treatment of polycondensation systems. Thus if a dibasic acid and a diol react to form a polyester, assumiag there is no possibihty of other side reactions to compHcate the issue, only linear polymer molecules are formed. When the reactants are present ia stoichiometric amouats, the average degree of polymerization, follows the equatioa ... 

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). 

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). 

Selective formation of MOM ethers has been achieved in a diol system. ... 

The classical method for acetonide formation is by reaction of a diol with acetone and an acid catalyst. ... 

Compounds i, ii, and iii can be prepared by an acid-catalyzed reaction of a diol and the cycloalkanone in the presence of ethyl orthoformate and mesitylenesul-fonic acid. The relative ease of acid-catalyzed hydrolysis [0.53 M H2SO4, H2O, PrOH (65 35), 20°] for compounds i, iii, acetonide, and ii is C5 C7 > ace-... 

Zn(BH4)2, TMSCl, Et20, 25°, 45 min, 77-97% yield. In this case reduction takes place to form a monobenzyl derivative of a diol. 

Reuaction with (/-Bu)2AlH affords a diol with one hydroxyl group protecteu as a MOM group. The more substituted hydroxyl bears the MOM group. ... 

Cyclic g-haloacetals and -ketals have been prepared by variations on two basic methods. The most frequently used method involves the combination of an a,B-unsaturated carbonyl compound (acrolein, methyl vinyl ketone, croton-aldehyde, etc.) a diol, and the anhydrous hydrogen halide. All possible sequences of combining these three have been used. In most cases the... 

Plasticizers can be classified according to their chemical nature. The most important classes of plasticizers used in rubber adhesives are phthalates, polymeric plasticizers, and esters. The group phthalate plasticizers constitutes the biggest and most widely used plasticizers. The linear alkyl phthalates impart improved low-temperature performance and have reduced volatility. Most of the polymeric plasticizers are saturated polyesters obtained by reaction of a diol with a dicarboxylic acid. The most common diols are propanediol, 1,3- and 1,4-butanediol, and 1,6-hexanediol. Adipic, phthalic and sebacic acids are common carboxylic acids used in the manufacture of polymeric plasticizers. Some poly-hydroxybutyrates are used in rubber adhesive formulations. Both the molecular weight and the chemical nature determine the performance of the polymeric plasticizers. Increasing the molecular weight reduces the volatility of the plasticizer but reduces the plasticizing efficiency and low-temperature properties. Typical esters used as plasticizers are n-butyl acetate and cellulose acetobutyrate. 

In a second step, the prepolymer was then reacted with a low molecular weight difunctional alcohol, commonly referred to as a diol or a diamine, to connect the prepolymer oligomers into a high molecular weight polyurethane. This step was referred to as the chain extension , resulting in the use of the term chain extenders to describe the low molecular weight diols or diamines that reacted with the prepolymer oligomers. 

Krespan ° has prepared a number of macrocycles, having both aza- and oxa-linkages in them, based on the 3,3-dimethyleneoxetane unit (see also Sect. 8.4 and Eq. 8.12). Typically, 3,3-bis(chloromethyl)oxetane is treated with a diol as shown in Eq. (3.40), in the presence of base. Once the bicyclic system is formed, further treatment with other nucleophiles (e.g., ammonia) can lead to opening of the 4-membered ring. 

Pure, discrete diethylene, triethylene and tetraethylene glycols are all commercially available from a variety of sources. Pentaethylene glycol and longer polyoxyethylene glycols are generally prepared by condensation of two equivalents of a shorter glycol with a diol dichloride or ditosylate. Such methods have been reported by Pedersen", Cornforth , and Krespan . The approach is illustrated in Eq. (7.1), below. 

The reaction depends, on the one hand, on the fact that fuchsin is decolorized by oxidizing agents (e.g. lead(IV) acetate) and, on the other hand, on the fact that lead(IV) acetate is reduced by compounds containing a-diol groups. It is, therefore, no longer available to decolorize the fuchsin. The fuchsin undergoes a Schiff reaction with the aldehydes that are formed [2]. 

An oxirane formed by the direct epoxidation, which usually occurs from the sterically least hindered side of the molecule, can be converted into its stereoisomer by a reaction sequence which involves the diaxial opening (in acetic acid at 100° for 2 hr) of the epoxide to a diol mo noacetate. Subsequent mesylation followed by treatment with base gives the inverted oxirane, as shown for the sequence (69) (70) (71) (72). ... 

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