Aliphatic diols

Among the vast number of naturally occurring or synthetic aliphatic polyalcohols, only a few have been used for the construction of phosphite ligands. Probably it is assumed that phosphites derived from simple diols, such as ethylene glycol, are 

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Boric acid esters provide for thermal stabilization of low-pressure polyethylene to a variable degree (Table 7). The difference in efficiency derives from the nature of polyester. Boric acid esters of aliphatic diols and triols are less efficient than the aromatic ones. Among polyesters of aromatic diols and triols, polyesters of boric acid and pyrocatechol exhibit the highest efficiency. Boric acid polyesters provide inhibition of polyethylene thermal destruction following the radical-chain mechanism, are unsuitable for inhibition of polystyrene depolymerization following the molecular pattern and have little effect as inhibitors of polypropylene thermal destruction following the hydrogen-transfer mechanism. 

Depending on dieir structure, properties, and syndietic methods, degradable polyesters can be divided into four groups poly(a-esters), poly(fi-esters), poly(lactones), and polyesters of aliphatic diols and diacids. 

From the preceding discussion, it is easily understood that direct polyesterifications between dicarboxylic acids and aliphatic diols (Scheme 2.8, R3 = H) and polymerizations involving aliphatic or aromatic esters, acids, and alcohols (Scheme 2.8, R3 = alkyl group, and Scheme 2.9, R3 = H) are rather slow at room temperature. These reactions must be carried out in the melt at high temperature in the presence of catalysts, usually metal salts, metal oxides, or metal alkoxides. Vacuum is generally applied during the last steps of the reaction in order to eliminate the last traces of reaction by-product (water or low-molar-mass alcohol, diol, or carboxylic acid such as acetic acid) and to shift the reaction toward the... 

Trifluoroacetic anhydride, which activates the polyesterification of 4-hy-droxybenzoic acid via the formation of a mixed anhydride,307 and 1,1 -carbonyldiimidazole308 were the first reported activating agents. The reaction between 1,1 -carbonyldiimidazolc and carboxylic acids proceeds through the formation of N-acylimidazolcs, which react with aliphatic diols in the presence of sodium ethoxide catalyst (Scheme 2.28). 

Trinitrochlorobenzene (piciyl chloride) in pyridine-A -mcthylpyrrolidi-none (NMP) solutions were later used for the preparation of polyesters from dicarboxylic acids and diphenols or aliphatic diols,309 but better results have been obtained with sulfonyl chlorides and phosphorus compounds. 

Aliphatic dinitriles, such as adipodinitrile, react with aliphatic diols at low temperature (0-5°C) in the presence of HC1 and form poly(iminoesters) which... 

Aliphatic dinitriles, reaction with aliphatic diols, 87-88 Aliphatic diols, 77... 

Yang and coworkers did the most efforts on the development of network polyester based on citric acid. " They investigated the reaction of citric acid with a series of aliphatic diols (from 3-16 carbon chains) and polyether diols such as polyethylene oxide (PEG), in which 1,8-octanediol (POC) and 1,10 decanediol (PDC) have been studied the most. 

The enzymatic synthesis of polyesters from activated diesters was achieved under mild reaction conditions. The polymerization of bis(2,2,2-trichloroethyl) glutarate and 1,4-butanediol proceeded in the presence of PPL at room temperature in diethyl ether to produce the polyesters with molecular weight of 8.2 x 10. Vacuum was applied to shift the equilibrium forward by removal of the activated alcohol formed, leading to the production of high molecular weight polyesters. The polycondensation of bis(2,2,2-trifluoroethyl) sebacate and aliphatic diols took place using lipases BC, CR, MM, and PPL as catalyst in diphenyl ether. Under the... 

The reactions of the six-membered chlorocyclophosphazene were studied with a number of aliphatic diamines (169 175), aromatic diamines (176), aliphatic diols (177-179), aromatic diols (180,181) and compounds containing amino and hydroxyl functional groups (169,170,182). This subject has been reviewed (11,16,20). There are at least five different reaction products that are possible (Fig. 19). Replacement of two chlorine atoms from the same phosphorus atom produces a spirocyclic product. Replacement of two chlorine atoms from two different phosphorus atoms in the same molecule produces an ansa product. Reaction of only one end of the difunctional reagent, resulting in the substitution of only one chlorine atom, leads to an open-chain compound. Intermolecular bridged compounds are formed when the difunc-... 

With aliphatic diols, although mixtures of products are formed, the predominant products are spirocycles 11,177). The reactions with the sodium salts of etheroxy diols such as tetra- and pentaethylene glycols... 

Several novel biodegradable polyesters of different compositions have been developed during the last decade, e.g., an aliphatic copolymer of various glycols and dicarboxylic acids (Bionolle) or copolymers of aliphatic diols and aromatic monomers [119-121]. 

A similar reducing system is created by combining dilithium catecholate and trichlorosilane at —78° in tetrahydrofuran. It is speculated that the relatively unstable pentacoordinate bis(l,2-benzenediolato)hydridosilicate (61) is formed in situ and that it is this species that can reduce aldehydes and ketones, but not esters, to alcohols when they are added to the reaction mixture at 0° (Eq. 168).93 In a like manner, the dilithium salt of 2,2/-dihydroxybiphenyl, which forms a pentacoordinate intermediate that is stable enough to react at room temperature, can also be used to promote the reduction reaction. The alkoxides of aliphatic diols... 

Table 4.3 Specifications of high molecular weight aliphatic diols [11].

The introduction of any flexible molecular repeat units, such as long-chain aliphatic diols or diacids, large hydrocarbon phases, such as C36 dimer acid,... 

Surprisingly little information is available on simple furanic urethanes and only one investigation on thermoplastic polyurethanes containing the heterocycle (34). The latter made use of difurylic diisocyanates with aliphatic diols to amve at structures like ... 

LC diols (la-lg) were synthesized by reacting 4,4 -terephthaloyl-dioxydibenzoyl chloride (TOBC) with excess aliphatic diols H0(CH2)rPH, n = 4-12. The semi-rigid, rodlike TOBC segments are well known to impart LC character to high polymers(17). 

Completely aliphatic polyesters, made from aliphatic diacid and aliphatic diol components), are not of major industrial importance because of their low melting temperatures and poor hydrolytic stability. (Low-molecular-weight aliphatic polyesters are used as plasticizers and prepolymer reactants in the synthesis of polyurethanes see Secs. 2-12e, 2-13c-2). 

Solid czs-1,2-diols and pyrocatechols react quantitatively with phenyl-boronic acid to form the phenylboronic esters upon stoichiometric milling. The water of reaction is taken up by the crystals and can be removed in a vacuum [90]. Thus, the aliphatic diols 186 and 189 give the borolic esters 188 and 190 with 100% yield (Scheme 25). Equally successful is the reaction of pyrocatechol (191) and 187. The reaction mixture is heated to 80 °C after milling at 0 °C. 

In general, enantiomer analysis by complexation gas chromatography can be performed without substrate derivatization. Aliphatic diols, however, have been separated as boronates or acetonides151. 

Copolynaphthalene ester films were prepared by transesterification/esterifi-cation of dimethyl naphthalene dicarboxylate and dimethyl isophthalate with aliphatic diols by Hebrink et al. (1) and used in optical polarizing films with color shifts. 

We have previously synthesized a number of titanium polyethers of the following general structure (3,4). A variety of aromatic and aliphatic diols were successfully incorporated as the fundamental backbone units of the polyethers. These materials are insoluble and do not soften prior to thermal-induced degradation. 

Thermoplastic copolyester elastomers are generally block copolymers produced from short-chain aliphatic diols, aromatic diacids, and polyalkylene ether-diols. They are often called polyesterether or polyester elastomers. The most significant commercial product is the copolymer from butane-1,4-diol, dimethyl terephthalate, and polytetramethylene ether glycol [25190-06-1/, which produces a segmented block copolyesterether with the following structure. 

Regioselective Acylation of Hydroxy Compounds. Aliphatic diols can be selectively acylated at the primary and secondary positions by a number of lipases in nonaqueous solvents... 

For the manufacture of a transparent, tough, thermally stable polycarbonate, the bis(chloroformate)s of isosorbide and isomannide were copolymerized with such dihydroxy compounds as dihydroxybenzenes and aliphatic diols by using the interfacial condensation method.127... 

Regioselective Acylation of Hydroxy Compounds. Aliphatic diols can be selectively acylated at the primary position by a number of lipases in nonaqueous solvents. For example, PPL suspended in solutions of various diols in ethyl carboxylates catalyzes transesterification in a highly regioselective manner, producing primary monoesters in up to 97% yield (93). Similarly, chloramphenicol [56-75-7] (72) (R = N02) can be acylated by a number of lipases to produce optically pure, water-insoluble 3-O-palmitate in a highly selective manner (94). 

Diols such as 87 are converted in excellent yields [89] into acetoxy chlorides (88) by treatment with trimethyl orthoacetate and trimethylsilyl chloride [90] or into acetoxybromides (89) with trimethyl orthoacetate and acetyl bromide [91]. These reactions proceed through nucleophilic attack on an intermediate l,3-dioxolan-2-ylium cation [91] with inversion of configuration. In the presence of an aryl substituent as in 87, displacement occurs exclusively at the benzylic position. With aliphatic diols such as 90, the halide is introduced mainly at the less hindered position and acetoxybromides 91 and 92 are formed in a ratio of 7 1. Treatment of the acetoxy halides 88 or 89 under mildly alkaline conditions affords epox.de 93 in 84-87% yield while the mixture of 91 and 92 is converted to epoxide 94 in 94% yield. Because both... 

Maleic anhydride [R1 equals -CH=CH- in Eq. (2.7) cis isomer] is reacted with aliphatic diols to form low molar mass unsaturated polyesters, UP. For molar masses higher than 1000 g/mol, products are diluted with a liquid vinyl monomer, most often styrene. This reactive mixture, generally called unsaturated polyester, UP resin, can be transformed into crosslinked polymers through a free-radical chain polymerization (see Sec. 2.3). 

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