2-Carboxy-6- phenol

Chemical Attachment. The initial step in chemically attaching enzymes to electrodes involves an activation (derivatization) of the support to introduce appropriate functional groups, such as carboxy, phenol, and quinone-like structures. This step is critical and must be controlled rigorously since the greater the number of functional groups, the higher will be the amount of immobilized enzymes attched and the better the final electrode activity. The electrode surface may be activated by different ways ... 

The olive mesocarp contains a number of phenolic and polyphenolic compounds and their esters, small amounts of which are present in olive oil (35, 43, 44). These include monohydroxy- and dihydroxy-phenylethanol, including tyrosol and other phenols and a series of carboxy-phenols, including caffeic, o-coumaric, p-coumaric, cinnamic, ferulic, gallic, p-hydroxybenzoic, protocatechuic, sinapic, syringic, and vanillic acids. Benzoic and cinnamic acids are produced by hydrolysis of flavonoids. The hydroxyphenyl-ethanols arise from hydrolysis of oleoeuropein. Their esters are responsible for the bitterness and pepperlike sensation occasionally dominant in the taste of olive oils. 

Members of this class are typified by saturated anacardic acid, (2-hydroxy-6-n-pentadecylbenzoic acid) which can be viewed as a fatty acid in which the carboxylic is now a carboxy phenolic or hydroxyphenolic group. The chemistry of these materials has been discussed in earlier reviews (ref. 2, 3) and the present review includes recent developments. 

In the context of multifunctionality, carbon black, a polycrystalline material, merits special mention. The surface layer of carbon black particles may contain quinones, phenols, carboxy phenols, lactones, etc. Therefore, apart from being a powerful UV absorber and a quencher of excited states (such as those of carbonyl groups), carbon black acts as a scavenger of free radicals in chain-breaking reactions and as a hydroperoxide decomposer [114, 115]. In polyethylene, carbon black forms a complex with macroradicals [115]. 

Phenolic compounds are weaker nucleophiles and better leaving groups than aliphatic alcohols. They do not yield polyesters when reacted with carboxylic acids or alkyl carboxy lates. The synthesis of polyesters from diphenols is, therefore, generally carried out through the high-temperature carboxylic acid-aryl acetate or phenyl ester-phenol interchange reactions with efficient removal of reaction by-product (Schemes 2.10 and 2.11, respectively). 

The lactone ring was then opened and the carboxy group converted to a hindered phenolic ester (Step F-4), providing the C(9)-C(16) intermediate. 

The functional groups of the enzyme involved in the chemical bonding are the TV-terminal and s-amino groups (from lysine) as well as the carboxy-(aspartic or glutamic acid), sulfhydryl- (cysteine), hydroxyl- (serine, threonine), indole (tryptophan), imidazole (hystidine) and phenolic (tyrosine) functions. 

The organic fraction composition may influence the exchange capacity. A key contribution to the exchange capacity of humus is given by the carboxyl and phenolic hydroxyl functional groups. Under appropriate pH conditions, uranic acids in polysaccharides or carboxy-terminal structures in peptides can contribute to the... 

Epichlorohydrin is reacted with a variety of hydroxy, carboxy, and amino compounds to form monomers with two or more epoxide groups, and these monomers are then used in the reaction with bisphenol A [Lohse, 1987]. Examples are the diglycidyl derivative of cyclohex-ane-l,2-dicarboxylic acid, the triglycidyl derivatives of p-aminophenol and cyanuric acid, and the polyglycidyl derivative of phenolic prepolymers. Epoxidized diolefins are also employed (Sec. 9-8). 

A number of studies on the fluorescence decay of tyrosine, tyrosine derivatives, and small tyrosyl peptides have been carried out. 36-38 Whereas the tyrosine zwitterion and tyrosine derivatives with an ionized a-carboxy group exhibited monoexponential fluorescence decay (x = 3.26-3.76 ns), double- or triple-exponential decay was observed in most other cases. As in the case of the tryptophan model compounds, the complex decay kinetics were again interpreted in terms of rotamer populations resulting from rotation around the C —Cp bond. There is evidence to indicate that the shorter fluorescence lifetimes may arise from rotamers in which the phenol ring is in close contact with a hydrated carbonyl group 36 37 and that a charge-transfer mechanism may be implicated in this quenching process. 39 ... 

Hydrazono-1-oxo- bzw. 2,6-Bis-[hydrazono]-l-oxo-cyclohexan werden durch Tetra-chlor-l,4-benzochinon zu 2-Hydroxy-azobenzol bzw. 2,6-Bis- phenylazo]-phenol dehy-driert. Die Methode kann auch auf in 4-Stellung mit Carboxy- oder Methyl-Gruppen substituierte Derivate angewendet werden2 ... 

Der Austausch einer Formyl- bzw. Carboxy-Funktion durch eine Nitro-Gruppe kann in 4-Formyl- bzw. 4-Carboxy-2-methoxy-phenol durch Reaktion mit Nitriersaure in 65%iger Ausbeute zum 2,4-Dinitro-6-methoxy-phenol erreicht werden1. Praparativ gesehen ist diese Methode aufgrund der extremen Nitrierbedingungen von geringem Interesse. 

The major functional groups in lignin are methoxy, phenolic hydroxy, aliphatic hydroxy, and carboxy groups. During reaction with alkylene oxide, most of the functional groups of lignin, besides methoxy groups, become... 

What about substituents that are groups other than HO, MeO or MDO (and of course the unsubstituted H) Homologues of MeO such as ethoxy and benzyloxy (EtO, BzO), alkyl groups such as methyl, phenyl, halides, carboxy or substituted carboxy groups, esters of phenols,... 

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