Dialcoholate

Lipase-catalyzed intermolecular condensation of diacids with diols results in a mixture of macrocycUc lactones and liuear oligomers. Interestingly, the reaction temperature has a strong effect on the product distribution. The condensation of a,(D-diacids with a,(D-dialcohols catalyzed by Candida glindracea or Pseudomonas sp. Upases leads to macrocycUc lactones at temperatures between 55 and 75°C (91), but at lower temperatures (<45°C) the formation of oligomeric esters predorninates. Optically active trimers and pentamers can be produced at room temperature by PPL or Chromobacterium viscosum Upase-catalyzed condensation of bis (2,2,2-trichloroethyl) (+)-3-meth5ladipate and 1,6-hexanediol (92). 

Tanno, T. and Shibuya, L., Special behaviour of para tertiary phenol dialcohol in poly-chloroprene adhesives. Adhesives and Sealant Council Meeting, Spring 1967. 

A reaction between two different monomers. Each monomer possesses at least two similar functional groups that can react with the functional groups of the other monomer. For example, a reaction of a diacid and a dialcohol (diol) can produce polyesters ... 

Various alkali metal derivatives Various dialcohols and diacids 123,164)... 

Various organic derivatives Various dialcohols and diacids 36,49,56, 66,69, 142-147, 149-159, 332... 

The reaction is carried out with metallic sodium or sodium hydroxide in a solvent like toluene, xylene, or dioxane. The mono- or dialcoholate reacts with chloroacetic acid or the sodium salt. 

Before considering the role of the electrode material in detail, there is one further factor which should be pointed out. The product of an electrode process may be dependent on the timescale of the contact between the electroactive species and the electrode surface, particularly when a chemical reaction is sandwiched between two electron transfers in the overall process. This was first realized when it was found that ir E curves and reaction products at a dropping mercury electrode were not always the same as those at a mercury pool electrode (Zuman, 1967a). For example, the reduction of p-diacetylbenzene at a mercury pool was found to be a four-electron process, giving rise to the dialcohol, while at a dropping mercury electrode the product was formed by a two-electron process where only one keto group was reduced (Kargin et al., 1966). These facts were interpreted in terms of the mechanism... 

A further example is given in reference [88] Selective esterification of retronecine, the dialcoholic component of a pyrolizidine alkaloid, by the imidazolide method was found to be superior to the acid chloride/pyridine method. Acylation of the 9-position of retronecine with tiglic acid, pivalic acid, isobutyric acid, and propionic acid was investigated concerning the steric requirement of the carboxylic acid. 

In the reaction with steroidal dialcohols, activated azolides attack the less hindered OH-group with a high degree of preference [136]... 

Another example of the same building principle is found in the literature 89) for the /5-analogous dialcoholic spiro host 24, namely in its 1 1 inclusion compound with benzene (Fig. 26). The host molecules are bound into infinite zigzag chains by H-bonds and disordered benzene molecules appear interstitially placed between such chains. 

Transesterification -dialcohol + diester -dialcohol + dicarboxylic acid Polyesters... 

Polyesters form via a condensation reaction between a dicarboxylic acid and a dialcohol to create an ester linkage, as shown in Fig. 24.1. By far, the two most common polyesters are polyethylene terephthalate and polybutylene terephthalate, the chemical structures of which are shown in Fig. 24.2. These two polymers differ from one another by the length... 

In addition to the desired polymerization reaction, the dialcohol reactants can participate in deleterious side reactions. Ethylene glycol, used in the manufacture of polyethylene terephthalate, can react with itself to form a dialcohol ether and water as shown in Fig. 24.4a). This dialcohol ether can incorporate into the growing polymer chain because it contains terminal alcohol units. Unfortunately, this incorporation lowers the crystallinity of the polyester on cooling which alters the polymer s physical properties. 1,4 butanediol, the dialcohol used to manufacture polybutylene terephthalate, can form tetrahydrofuran and water as shown in Fig. 24.4b). Both the tetrahydrofuran and water can be easily removed from the melt but this reaction reduces the efficiency of the process since reactants are lost. 

It should be noted that dialcohols 486, 487, and 488, obtained during the synthesis are stereoisomers of 18-hydroxy-a-yohimbine, which has an al-... 

R. Taylor and C. F. Macrae, Rules governing the crystal packing of mono and dialcohols. Acta Cryst. B (Struct. Sci.) 57, 815 827 (2001). 

In theory, almost any comonomer diacid or dialcohol could lead to amorphous copolymers of PET. For example, incorporation of 20-80% of 2,6-naphthalate, or greater than 30% of isophthalate, will generate amorphous materials [9], Amorphous copolymers of PET, produced by the wholesale substitution of other monomers into the polymeric backbone, rarely possess desirable thermomechanical properties, unlike the Eastman PETG compositions. 

Polyesters are one of the most important classes of polymers in use today. In their simplest form, polyesters are produced by the polycondensation reaction of a glycol (or dialcohol) with a difunctional carboxylic acid (or diacid). Hundreds of polyesters exist due to the myriad of combinations of dialcohols and diacids, although only about a dozen are of commercial significance. 

Nylon-66 is made by the condensation polymerization of the dicarboxylic acid adipic acid, and 1,6-diaminohexane, an amine. (The number 66 comes from the fact that each of the two reactants contains six carbon atoms.) This reaction results in the formation of amide bonds between monomers, as shown in Figure 2.13. Condensation polymers that contain amide bonds are called nylons or polyamides. Condensation polymers that contain ester bonds are called polyesters. Polyesters result from the esterification of diacids and dialcohols. 

Thermoplastic polyesters result from the copolymerization of a diacid and a dialcohol under conditions that lead to formation of a linear macromolecule. 

Section III,B> ) The two methyl groups in 34 were formed from the corresponding methyl esters via reduction to the bis-hydroxymethyl compound followed by ditosylation and reduction with LAH. Both the intermediate diester and the derived dialcohol were separately cyclized to give the corresponding octahydrodibenzothiophenes (50% and 80%, respectively). However, no attempt to dehydrogenate these compounds to the dibenzothiophenes was made. This reaction obviously has considerable potential. 

Periodic acid oxidation has proved to be a very useful tool in enzymology since a wide variety of biochemicals contain hydroxyl groups on adjacent carbon atoms. For example, periodate-oxidized ATP (also called adenosine 5 -triphosphate 2, 3 -dialdehyde) has often been used as an alternative substrate or an irreversible inhibitor for a wide variety of ATP-utilizing enzymes. This compound, and many others, are now commercially available, even though they are readily synthesized e.g., periodic acid oxidized ADP, AMP, adenosine, P, P -di(adenosine-5 )pentaphosphate, P, P -di(adenosine-5 )tetraphos-phate, GTP, GDP, GMP, guanosine, CTP, CDP, CMP, etc. In the case of the nucleosides, commercial sources also can supply the dialcohol form of the nucleoside i.e., the nucleoside has first been oxidized with periodic acid and then reduced to the dialcohol with borohydride. 

The formation of polyesters from a dialcohol (diol) and a dicarboxylic acid (diacid) is used to illustrate the stepwise kinetic process. Polymer formation begins with one diol molecule reacting with one diacid, forming one repeat unit of the eventual polyester (structure 4.3) ... 

DuPont had trouble in finding a suitable polyester, because esters of most diacids and dialcohols hydrolyze too easily. Clothing that dissolves in the rain or washing machine is clearly not very satisfactory. However, Imperial Chemical Industries (ICI) in England, a company almost as old and large as DuPont, found the best one, polyethylene terephthalate, which they sold to DuPont, and PET is still the most important polyester. 

OE031 Ghimenti, G., and G. Taponeco. Ter- OE041 penic dialcohols in olive oil and their modification during the course of refining. Riv Soc Ital Sci Aliment 1974 ... 

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