Stabilization phenols

Because of its hardness and ability to be electroplated, together with good dimensional stability, phenolic mouldings are used in the manufacture of golf ball heads for typewriters. 

Organic acids convert the blue mesomerically stabilized phenolate anion to the red undissociated acid. Reductones (e.g. ascorbic acid) reduce the reagent to a colorless salt. 

Cured phenolic resins have outstanding heat resistance, resistance to cold flow, good electric (insulation) properties, and good dimensional stability. Phenolic resins have good adhesive properties and are employed in the production of sandpaper, abrasive wheels, and brake linings. These resins are also used as casting resins. 

The situation is different for phenols because of the inclusion of the carbon-carbon double bond into the aromatic ring and the associated aromatic stabilization. Phenol (benzenol) exists exclusively in the enol form ... 

This report was followed by a continuing report by Arny et al. in which they addressed the "Peculiarities of the Individual Chemicals" (26). As part of the study, these authors reviewed the literature and evaluated several photostabilizers suggested in the literature. All but one of these stabilizers gave satisfactory results in their hands. Tin compounds were found useful for stabilizing phenol and peroxides. Acetanilide was found to protect hydrogen peroxide. 

Used as a thermo/light-stabilizing phenolic antioxidant in the manufacture (compounding and end use) of white, light-colored, and transparent vulcanizates based on natural or synthetic rubber, PS, polyolefins, and pentaplast. Also used in POM and ABS thermoplastics because of its low volatility and migration properties. 

In many stabilizer formulations, different types of stabilizers are used. As processing stabilizer phenolic antioxidants and phosphites are applied, for long-term heat stability phenolic antioxidants and thioethers are used and for UV stability, combinations of HALS with other types of UV stabilizers can be applied. HALS stabilizers show interactions with these types of stabilizers that can lead to synergisms as well as antagonisms. 

Due to the free-radical character of both the y-radiation induced transformation and oxidation in the post-irradiation phase, free-radical scavenging stabilizers - phenols and amines - effectively protect PO [11,226,227]. This was confirmed by excellent antioxidant/antiradiant effects of DP A, PNA and PD in particular in the post-y-irradiation phase of PO and elastomers [11]. Oligomeric DHQ 21 or its combination with 9b efficiently stabilized EPDM or X-LPE used as insulation materials for electric cables exposed to irradiation doses up to 2MGy at a dose rate 300 Gy h 1 [242]. 

Hydroxy-3,5-di-(1,1-dimethyibenzyl) phenyi]-2H-benzotriazoie UV stabiiizer, pharmaceuticals Benzophenone-3 UV stabilizer, phenolics Benzophenone-8 UV stabilizer, photo Octrizoie... 

Later on, the same group also reported a series of cysteine-stabilized phenolic resin-based polymer and CS prepared by the modified Stdber method [77], They believe cysteine plays a very important role in the formation of such nanospheres, acting as a particle stabilizer and a source of heteroatoms (nitrogen and sulfur) that can be introduced into these spheres. The diameter of these spheres can be tuned in the range of 70-610 nm by adjusting the cysteine amount and reaction temperature. Since polymer spheres obtained in the presence of cysteine contain sulfur and nitrogen heteroatoms, they are promising in CO2 capture. 

An alternative explanation for the greater acidity of phenol relative to cyclohexanol can be based on similar resonance structures for the phenoxide ion. Unlike the structures for phenol, 2—4, resonance structures for the phenoxide ion do not involve charge separation. According to resonance theory, such structures should stabilize the phenoxide ion more than structures 2-4 stabilize phenol. (No resonance structures can be written for cyclohexanol or its anion, of course.) Greater stabilization of the phenoxide ion (the conjugate base) than of phenol (the acid) has an acid-strengthening effect. 

Costabilizers enhancing light stability phenolic antioxidant (e.g. DEOX10 and 76) and hindered amine (e.g.Chiguard 770 and 944) ... 

Costabilizers enhancing light stability phenolic antioxidants, phosphites and... 

Phosphor compounds are utilized for thermal-oxidative and thermal stabilization. Phenols, amines, and thio ethers are also used to stabilize polyesters. 

Chemical structures of several phenolic antioxidants are presented in Scheme 1. Hindered phenolic antioxidants (AO) are the chemically most diversified group of stabilizers. Phenolic moities also constitute an important part of UV light absorbers and metal chelators. 

The eombination of high moleeular mass phenolie antioxidants with phosphites or phosphonites confer adequate proteetion. They are now the state of the art for PP, HDPE, and LLDPE stabilization. Phenolic antioxidants can confer sufficient processing stability to Ziegler-type high density polyethylene (HDPE, Ti-based catalysts) used for tape manufacturing. However, with HDPE, as with PP fibers, the combinations of phenolic antioxidants with phosphites or phosphonites yield improved processing stability. These combinations are characterized by good extraction resistance, low volatility, and positive influence on substrate color [6, 7]. 

HAS light/UV stabilizers, phenolic antioxidants, benzophenone stabilizers, antioxidants, phosphite antioxidants, bis(tribomophenoxy)ethane... 

Although molds made with clay or sodium silicate binders are inexpensive, they have low dimensional tolerance and low stability. Phenolic resins used as binders have many good properties such as excellent dimensional stability, fast curing times, and excellent storage of cores and shells. In some applications furfuryl alcohol and urea formaldehyde resins are also used. - ... 

The addition of stabilizers such as zinc dibutyl dithiocarbamate (about 0.3 phr) improves high-temperature processing stability. Phenolic antioxidants such as 2,2 -methylene bis(4-methyl-6-rert-butyl phenol) and 2,2 -methyl bis(4-ethyl-6-rert-butyl phenol) are added with dilauryl thiodipropionate (DLTDP) into TPE compound. Dilauryl thiodipropionate (DLTDP) plays a synergistic effect with phenolic antioxidants. 

Tyrosine possesses a phenolic proton which is more readily deprotonated because deprotonation forms a resonance-stabilized phenolate ion. In contrast, deprotonation of the OH group of serine gives an aUcoxide ion that is not resonance-stabilized. As a result, the OH group of tyrosine is more acidic than the OH group of serine. 

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