Polymers, hydroxy substituted

Platinum-group metals (qv) form complexes with chelating polymers with various 8-mercaptoquinoline [491-33-8] derivatives (83) (see Chelating agents). Hydroxy-substituted quinolines have been incorporated in phenol—formaldehyde resins (84). Stannic chloride catalyzes the condensation of bis(chloromethyl)benzene with quinoline (85). 

Because of their completely saturated heterocycle, leucoanthocyanidins, together with flavan-3-ols are referred to as flavans. Examples of flavan-3-ols are catechin (1.39) and gallocatechin (1.40). The gallo in the latter compound refers to the vic-tri-hydroxy substitution pattern on the B-ring. Unlike most other flavonoids, the flavans are present as free aglycones or as polymers of aglycones, i.e. they are not glycosylated. 

Furfural-resorcinol oligomers have been known for many years (15,16). The reaction velocity of furfural with resorcinol is the fastest compared to other hydroxy substituted aromatics. Furfural-resorcinol polymers, when heat cured, give excellent bonding strengths, especially under conditions of high humidity. Their oligomers, even in the presence of acids, show good shelf life until reacted with a suitable methylene donor. 

The nickel-mediated polymerization of p-hydroxy-substituted phenyl isocyanide 60 (R=H) afforded the corresponding poly(isocyanide) 65 in a 43% yield after 65 h at room temperature [81]. The polyhydroxylated polymer 65 was oxidized with NaOCl in THF (Scheme 43). The resultant black solid 66,... 

Quinone Cleavage and Resistance to Peroxide Treatment Hydrogen peroxide readily oxidizes o- and p-quinones via ring cleavage, forming colorless, open-chain carboxylic acids [21]. This is the predominant reaction, however, colored products may also be formed, particularly at high alkali concentrations. There is firm evidence for the formation of hydroxy-substituted quinones. In addition, the formation of quinone polymers has also been proposed. The hydroxy-quinones are probably formed... 

Other o-nitrophenol-containing resins have been prepared with the aim of increasing the distance between the reactive center and the macromolecular backbone, which should accelerate the active ester formation by achieving an easier approach of the reagents. Thus, the Friedel-Crafts alkylation of styrene-divinyl-benzene copolymer with 4-hydroxy-3-nitrobenzyl chloride promoted by aluminium trichloride gave 4-hydroxy-3-nitrobenzylated polystyrene (70) (approximately 30% of the aromatic rings of the polymer were substituted according to elemental... 

A short review of photo-oxidation of a range of polymers by Faucitano and co-workers [30] summarised the understanding at the time of PET photolysis as a splitting of C-0 bonds in the ester gronps, with formation of acyl and carboxyl radicals, which themselves can lose carbon oxides to produce phenyl or alkyl radicals, or abstract hydrogen to produce aldehydes and carboxylic acids. When oxygen is present, the authors state that the autoxidation chain reaction will lead to formation of anhydrides and aldehydes, and to hydroxy-substituted phenyl species. 

Another newer version of HALS is exemplified by hydroxy-substituted N-alkoxy hindered amines, i.e., molecules with at least one active moiety of the structure >N-OR-(OH). A very wide range of such additives has been covered in a family of patents assigned to Ciba Speciality Chemicals [193-198], and claims for applications include aromatic polyesters. These additives are said to have as good as or better UV stabilising ability and antioxidant properties as the earlier HALS. The hydroxyl group(s) is said to impart additional advantages not possible with the NOR types, e.g., antistatic attributes, and better pigment dispersion in polar polymers. 

The advantage of this one-pot preparation method is that the ehromophores are attached to the polymer backbone at the last stage using a very mild condensation reaction between die hydroxy substituted polyimide and a hydroxy-substituted chromophore. This avoids the harsh imidization process and the necessity of preparing the chromophore-containing diamine monomers. The method also allows a wide variety of polyimide backbones. 

Oxidative Eiectropoiymerization of Poiypyridyi Compiexes. Oxidative electropolymerization of suitably substituted [M (bipy)3l + complexes offers an alternative approach to the preparation of electrochromic redox active polymer films. Oxidative eiectropoiymerization has been described for iron(II) and ruthenium(II) complexes containing amino-substituted (31) and pendant aniline-substituted (32) 2,2 -bipyridyl ligands, and amino- and hydroxy-substituted 2,2 6, 2"-terpyridinyl ligands (33) [ligand structures (4) and (5)]. Analysis of IR spectra suggests that the eiectropoiymerization of [Ru(L )2l + [L = (4)], via the pendant aminophenyl substituent, proceeds by a reaction mechanism similar to that of aniline (33). The resulting metallopolymer film reversibly switches from purple to pale pink on oxidation of Fe(II) to Fe(III). For polymeric films formed from [Ru(L )2l + [L = (5)], via polymerization of the pendant hydroxyphenyl group, the color switch is from brown to dark yellow (see Electropolymerization). 

Polymers from hydroxy-substituted fatty acids or esters, derived from fats and oils and bifunctional compounds, have been reported [277]. The fat- and glyceridic oil-derived monomers used represent an inexpensive and readily obtainable monomer source for the preparation of condensation polymers from hydroxy- or amino-substituted fatty acids (e.g. 12-hydroxystearic acid) with difunctional compounds (e.g. diamines, polyamines, amino alcohols, diols, polyols, diacid chlorides, diisocyanates, phosgene, etc.). 

The electrochemical polymerization of Ti-electron-rich aromatics, such as aniline, pyrrole and thiophene, to obtain electrically conducting polymers is well-known. Some reports describe the polymerization of amino-, pyrrolyl- and hydroxy-substituted tetraphenylporphyrins and suitable substituted phthalocyanines (for reviews see [230,231]) (anodic electropolymerization of 2,9,16,23-tetraaminophthalocyanine (M = Co(II), Ni(II)) [231,232] and 2,9,16,23-tetra(l-pyrrolylalkyleneoxy)phthalocyanines (M = 2H, Zn(II), Co(II) [232])) under formation of polymers 53 and 54 shown as idealized structures. Depending on the reaction conditions the film thicknesses are between around 50 nm and several pm. The films remain electroactive at the electrochemical potential so that oxidation or reduction current envelope grows with each successive potential cycle. Electrochromism, redox mediation and electrocatalysis of the electrically conducting films are summarized in [230,231]. 

In addition to epoxy resins, MA has been investigated as a crosslinker for a variety of polymers. For example, poly(oxycyclohexene), polyary-lates, hydroxy-substituted polyspiro resins,and polymethyl-siloxanes have been crosslinked with MA to give thermoplastic adhesives, heat-resistant polyarylates, electrical insulating materials, and other composites. 

N-alkyl-3-azetidinols, obtained from epidilorohydrin and a primary amine, have been polymerized to low-molecular-weight hydroxy-substituted polyamines. Transesterification of an azetidinol with methyl acrylate or methacrylate leads to the corresponding azetidinyl esters which can be polymerized or copolymetized with other vinyl monomers to produce reactive, cross-linkable polymers (Scheme 18). 

II. B polyethylene glycol, ethylene oxide, polystyrene, diisocyanates (urethanes), polyvinylchloride, chloroprene, THF, diglycolide, dilac-tide, <5-valerolactone, substituted e-caprolactones, 4-vinyl anisole, styrene, methyl methacrylate, and vinyl acetate. In addition to these species, many copolymers have been prepared from oligomers of PCL. In particular, a variety of polyester-urethanes have been synthesized from hydroxy-terminated PCL, some of which have achieved commercial status (9). Graft copolymers with acrylic acid, acrylonitrile, and styrene have been prepared using PCL as the backbone polymer (60). 

Numerous substituted derivatives of chitin and chitosan are known [67] some important examples are shown in Scheme 10.9. The possibility of forming either anionic (5,7,8,11) or cationic (9,12) derivatives should be noted. The O-carboxymethyl (5) and N-carboxymethyl (11) polymers are of particular interest as they have stronger complex-forming capabilities with metal ions than either unsubstituted chitosan or EDTA [65]. In practice, derivatives formed by substitution via the 2-amino group of chitosan are more common than those substituted via the 6-hydroxy position of the glucopyranose grouping [65]. 

The enzymatic polymerization of lactones could be initiated at the hydroxy group of the polymer, which expanded to enzymatic synthesis of graft copolymers. The polymerization of c-CL using thermophilic lipase as catalyst in the presence of hydroxyethyl cellulose (HEC) film produced HEC-gra/f-poly( -CL) with degree of substitution from 0.10 to 0.32 [102]. 

Carboxymethyl cellulose is normally used at a degree of substitution of around 0.1 (i.e. the number of hydroxy groups substituted per glucose residue), which renders the polymer water soluble. Further water solubility can be obtained by increasing the degree of substitution. 

Lignin is a polymer built up of phenylpropane units substituted with hydroxy and methoxy groups, see Figure 48. Lignin is a three-dimensional molecule like a 3-D matrix, see Figure 48 [65]. 

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