Chain branching esters

Secondary and branched-chain alkyl esters isopropyl [689-12-3] 52 13.7 1.4060 0.8932... 

It is also possible to prepare them from amino acids by the self-condensation reaction (3.12). The PAs (AABB) can be prepared from diamines and diacids by hydrolytic polymerization [see (3.12)]. The polyamides can also be prepared from other starting materials, such as esters, acid chlorides, isocyanates, silylated amines, and nitrils. The reactive acid chlorides are employed in the synthesis of wholly aromatic polyamides, such as poly(p-phenyleneterephthalamide) in (3.4). The molecular weight distribution (Mw/Mn) of these polymers follows the classical theory of molecular weight distribution and is nearly always in the region of 2. In some cases, such as PA-6,6, chain branching can take place and then the Mw/Mn ratio is higher. 

Several ester-based oils are suitable as lubricants [532,690], as are branched chain carboxylic esters [1588]. Tall oils can be transesterified with glycols [1536] or condensed with monoethanolamine [51]. 

The most common copolymer of this type is ethylene-vinyl acetate, which we normally refer to as EVA. This variety of polyethylene is illustrated in Fig. 18.2 e), in which the ester branches are indicated by the symbol VA This family of copolymers is commercially available containing vinyl acetate concentrations of up to approximately 25 mole %. In addition to the randomly distributed ester branches, these resins also contain the short and long chain branches that are characteristic of low density polyethylene. 

We can also incorporate branches by copolymerizing ethylene with vinyl esters and vinyl acids. In addition to their ester or acid side groups, these copolymers also contain the long and short chain branches, which are characteristic of low density polyethylene. 

It has been known for some time [see Ref. (176) for earlier work] that if poly(vinyl alcohol), produced by hydrolysis of poly(vinyl acetate) is reacetylated, the PVAc so obtained has a lower MW than the original PVAc prior to hydrolysis, though the MW of the material is not lowered any further by subsequent cycles of hydrolysis and reacetylation. Various explanations had been advanced for this phenomenon Wheeler explained it as a consequence of the presence of branches joined to the main chain through ester linkages which would be broken on hydrolysis and not re-formed on reacetylation. These branches were ascribed to chain transfer reactions with acetate groups, either in the polymer, or in monomer molecule subsequently polymerized at their double bonds. Transfer reactions by attack on hydrogen atoms other than those in... 

POLYHYDRO XYLIC BRANCHED-CHAIN ALCOHOL ESTERS... 

Co-polymerization of pentaerythritol and two other monomers—an unsaturated acid and benzene 1,3-dicarboxylic acid—gives a network of polymer chains branching out from the quaternary carbon atom at the centre of pentaerythritol. The reaction is simply ester formation by a carbonyl substitution reaction at high temperature (> 200°C). Ester formation between acids and alcohols is an equilibrium reaction but at high temperatures water is lost as steam and the equilibrium is driven over to the right. 

The influence of compound structure on CNs of fatty compounds was discussed (Harrington, 1986) and hypotheses confirmed by practical cetane tests (Freedman et al, 1990 Ladommatos et al, 1996 Klopfenstein, 1985 Knothe et al, 2003). CNs of neat fatty compounds are given in Table 1.1. In summary, CNs decrease with increasing unsaturation and increase with increasing chain length, i.e., uninterrupted CH2 moieties. However, branched esters derived... 

Knothe, G., Matheaus, A. C., and Ryan, T. W. III. 2003. Cetane Numbers of Branched and Straight-Chain Fatty Esters Determined in an Ignition Quality Tester. Fuel, 82, 971-975. 

Acetate esters Fatty acid ethyl esters Branched chain ethyl esters A Flowery, fruity, estery Yes Yes... 

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