Hydroxyphenyl-valeric acid

Bis(4-hydroxyphenyl) sulfide, tl45 4,4-Bis(hydroxyphenyl)valeric acid, b203... 

Starting from a hyperbranched polyester based on 4,4 -bis(hydroxyphenyl)valeric acid, terminal -OH groups were derivatized to yield the hyperbranched macroinitiator. The Hgand precursor was introduced as the first block in the grafting from reaction, followed by 2-methyl-2-oxazoHne polymerization to give the second block and allow for water-soluble polymers. The triphenylphosphine-functionalized am-phiphihc star block copolymer was obtained after transformation of the iodoaryl... 

Other cyclic tetrapeptides have also been isolated by Japanese workers and AM toxins I, II, and III, isolated from Alternaria mail., are extremely toxic to certain plant species (9.10). These are constructed of L- i-hydroxyisovaleric acid, L-alanine, c-amino-acrylic acid and, in AM toxin I, L-6(-amino- -( .-methoxyphenyl)-valeric acid. The phenyl residue in AM toxin II is L-t(-amino-S-phenylvaleric acid, while in AM toxin III, it is L-ol-amino-( .-hydroxyphenyl)valeric acid (Figure 2), All the AM toxins produce leaf spot, or necrosis, in apple but as might he expected slight change in substitution (R-group) on the phenyl ring radically alters the specific activity of the molecule. Both AM toxin I and III induce interveinal necrosis in the "Indo" apple cultivar, which is also highly susceptible to A. mail. at concentrations as low as 0.1 pph within 18 h after treatment. In contrast, the resistant apple cultivar "Jonathan" is only affected by 1 ppm of AM toxin I and 10 ppm of AM toxin III. 

Bis(4 -hydroxyphenyl)valeric acid (15.1 g, 52.7 mmol) is a commercial monomer but has to be used in high purity (not colored). If the purity of the chemical as received is not sufficient it has to be purified by column chromatography. 

Example 4.3 Preparation of a Hyperbranched Polyester by Polycondensation of 4,4-bis(4 -hydroxyphenyl)Valeric Acid... 

Bis(4 -hydroxyphenyl)valeric acid and 3 drops of dibutyl tin diacetate are placed in a dry standard apparatus with mechanical stirrer connected to a vacuum line. The polycondensation is carried out in two steps in order to obtain high conversion and high molar mass First, the monomer is stirred in a nitrogen stream for 70 min at 200°C during this time period an increase in viscosity of the melt should be observed. After that, vacuum is applied at 225°C for 3 h with stirring and then for 1 h without stirring until a final vacuum of 0.010 mbar is reached. The crude product is dissolved twice in approximately 100-150 ml THF and precipitated into 500 ml water. After filtration the product is dried over phosphorus pentaoxide for several days. 

II and III are identical except for the L-a-amino-5-phenylvaleric acid and L-a-amino-5-(p-hydroxyphenyl)-valeric acid residues, respectively (Fig. 8). While all the AM toxins produce leaf spot and necrosis in susceptible apple varieties, as does the pathogen, even resistant varieties appear not to be immune to the toxin. For example, Indo which is very vulnerable to l. mali is also affected by toxins I and... 

The design of diiron complexes functionalized with methacrylate units was also achieved using complex 9. The synthesis of complex 9 was previously reported by the reaction of the 1,4-dichlorobenzene complex of cyclopentadienyliron with 4,4-to(4-hydroxyphenyl)valeric acid. Scheme 3 shows the synthesis of monomer 11 via condensation of an acid chloride complex (10) with 2-hydroxyethyl methacrylate (5). Monomer 11 was isolated as a yellow precipitate in excellent yield. 

A one-pot solution polymerization was performed at room temperature using partially aromatic monomers, namely 4,4-bis(4 -hydroxyphenyl)valeric acid as AB2 and 3-(4-hydroxyphenyl)propionic acid as AB [118] (see Table 1, entry 5 for monomer combination), in the presence of 4-(A, A dimethylamino) pyridinium 4-tosylate (DPTS) as catalyst and dicyclohexylcarbodiimide (DCC). The dependencies of the DB and the thermal properties of the polymers on the AB AB2 monomer ratio were studied. Polyesters with statistical dendritic topology, controlled DB, and > 35,000 g/mol were obtained. The DB was found to decrease with an increase in the amount of AB monomers and increasing comonomer ratio in the polymer (rp = ratio of AB to AB2) as shown in Fig. 1. Interestingly, the DB for hb homopolyester and branched copolyester at rp = 0.46 was similar (see Fig. la), because of the fact that on adding the small-sized linear AB to the more voluminous AB2 monomers in the reaction mixture, the steric effects decreased, which promoted the formation of dendritic units formed by the AB2 monomer. The thermal... 

Kricheldorf HR, Hobzova R, Schwarz G (2003) Cyclic hypta branched polyesters dtaived from 4,4-bis(4 -hydroxyphenyl)valeric acid. Polymer 44 7361-7368... 

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