Trifunctional products

The ATPEs have a poly(propylene oxide) backbone widi amine endgroups, as shown in Scheme 4.4. There are several routes to such materials,25 but the only one in current commercial production is die direct amination of polyether polyols. A line of uretiiane-grade ATPEs is made by Huntsman under the tradename Jeffamine. Mono-, di-, and trifunctional products are available in molecular weights up to 5000 g/m. 

Various molecules are available, where n and m are varied systematically. Trifunctional products are also available where the starting material is glycerol these have the structure ... 

Trifunctional products (1.8) are also available where the starting material is glycerol. 

The second type of EO/PO copolymers are prepared by reaction of polyethylene glycol (difunctional) with PO or mixed EO/PO. These will have the structure (PO) (EO) j(PO)n and they are referred to as reverse Pluronics. Trifunctional products are also available where the starting material is glycerol. These have the structure... 

Another significant use of 3-methylphenol is in the production of herbicides and insecticides. 2-/ f2 -Butyl-5-methylphenol is converted to the dinitro acetate derivative, 2-/ f2 -butyl-5-methyl-4,6-dinitrophenyl acetate [2487-01 -6] which is used as both a pre- and postemergent herbicide to control broad leaf weeds (42). Carbamate derivatives of 3-methylphenol based compounds are used as insecticides. The condensation of 3-methylphenol with formaldehyde yields a curable phenoHc resin. Since 3-methylphenol is trifunctional with respect to its reaction with formaldehyde, it is possible to form a thermosetting resin by the reaction of a prepolymer with paraformaldehyde or other suitable formaldehyde sources. 3-Methylphenol is also used in the production of fragrances and flavors. It is reduced with hydrogen under nickel catalysis and the corresponding esters are used as synthetic musk (see Table 3). 

Products intermediate to the flexible and rigid foams may be obtained from castor oil (a trihydroxyl molecule), synthetic triols of moderate molecular weight and polyesters with a moderate amount of trifunctional hydroxyl compound in the strueture. Current practice, however, is to use tipped polyols of the type used for flexible foams with MDI. Semi-rigid foams are used for such purposes as crash pads, car steering wheels and packaging equipment. 

As explained earfier step polymerisations generally occur by condensation reactions between functionally substituted monomers. In order to obtain high molar mass products bifuncfional reactants are used monofunctional compounds are used to control the reaction while trifunctional species may be included in order to give branched or crosslinked polymers. A number of types of reaction may be involved, as described briefly in the following paragraphs. 

Flory (5) states that gelled, insoluble products are formed by the inter-molecular reaction of units which are trifunctional or higher. An infinite network structure is formed however, it is limited only by the volume of the reaction mixture. The monomer size controls the rate of reaction. 

The pyrolysis of the coammonolysis products was studied. The 6 CH3SiHCl2/l HSiCl3 ammonolysis product would be the least cross-linked since it contains the least amount of trifunctional component and, as expected, low ceramic yields were obtained on pyrolysis of these products. Pyrolysis of the 3 1 products gives increased ceramic yields, while pyrolysis of the most highly cross-linked 1 1 ammonolysis products gives quite good ceramic yields, 72% for the product prepared in Et20 78% for that prepared in THF. 

Double hydrophilic star-block (PEO-fo-PAA)3 copolymers were prepared by a combination of anionic and ATRP of EO and fBuA [150]. Three-arm PEO stars, with terminal - OH groups were prepared by anionic polymerization, using l,l,l-tris(hydroxymethyl)ethane, activated with DPMK as a trifunctional initiator. The hydroxyl functions were subsequently transformed to three bromo-ester groups, which were utilized to initiate the polymerization of f-butyl acrylate by ATRP in the presence of CuBr/PMDETA. Subsequent hydrolysis of the f-butyl groups yielded the desired products (Scheme 74). 

Collagen cross-links. Besides amide bonds between amino acids in the same a chain, bonds between amino acid side chains of different a chains can form "cross-links". These bonds originate from enzymatically-oxidized side chains of lysine and hydroxylysine residues. The oxidized residues react with other lysine and hydroxylysine residues, forming difunctional products. Reactions of such products with oxidized lysine or hydroxylysine yield trifunctional cross-links (Reiser et al., 1992). 

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