Phenylenediamine antioxidant

Mixed diaryl—y -phenylenediamines, antioxidant of The Goodyear Tire Rubber Co. Accelerator of Monsanto Co. 

Hindered phenol and phenylenediamine (PDA) compounds are commonly used and quite effective at preventing free-radical oxidative degradation of fuel. They can be used in gasoline, kerosene, jet fuel, and certain distillates and lubricants. Often, a synergistic effect can be obtained by using a combination of a hindered phenol and a phenylenediamine antioxidant in the same application. 

Perform as an effective substitute for a hindered phenol or phenylenediamine antioxidant in inhibiting free radical reactions in gasoline or jet fuel. 

Anilinophenyl methacrylamide N,N -Di (n-octyl)-p-phenylenediamine antioxidant, brewing Erythorbic acid antioxidant, cancer Thioctic acid... 

Di-t-butyl-4-hydroxybenzoic acid, n-hexadecyl ester antioxidant, mastic adhesives Phenol, styrenated antioxidant, meat Citric acid monohydrate antioxidant, mech./molded rubber goods Phenol, styrenated antioxidant, mercaptans N,N -Di (n-octyl)-p-phenylenediamine antioxidant, metal-catalyzed breakdown Disodium EDTA antioxidant, metals Hydrogen... 

BHT Bisphenol A, polybutylated Diphenylamine-acetone Distearyl thiodipropionate Nickel dibutyidithiocarbamate Zinc diisobutyidithiocarbamate Zinc 2-mercaptotoluimidazole antioxidant, SR rubber food-contact Cyclohexyl-N -phenyl-p-phenylenediamine antioxidant, stabilized polymers Perchloropentacyclodecane antioxidant, staining carpet backcoating latex foams... 

N,N -Diphenyl-p-phenylenediamine antioxidant/antiozonant, flex-resistant rubber N,N -Diphenyl-p-phenylenediamine antioxidant/antiozonant, footwear... 

Oxidation of LLDPE starts at temperatures above 150°C. This reaction produces hydroxyl and carboxyl groups in polymer molecules as well as low molecular weight compounds such as water, aldehydes, ketones, and alcohols. Oxidation reactions can occur during LLDPE pelletization and processing to protect molten resins from oxygen attack during these operations, antioxidants (radical inhibitors) must be used. These antioxidants (qv) are added to LLDPE resins in concentrations of 0.1—0.5 wt %, and maybe naphthyl amines or phenylenediamines, substituted phenols, quinones, and alkyl phosphites (4), although inhibitors based on hindered phenols are preferred. 

Antidegradants. Amine-type antioxidants (qv) or antiozonants (qv) such as the phenylenediamines (ppd) can significantly decrease scorch time. This is particulady tme in metal oxide curing of polychloroprene or in cases where the ppd had suffered premature degradation prior to cure. 

Solubility. Another desirable property of a degradant is its high solubihty in mbber but poor solubihty in water and solvents that come in contact with mbber. Poor solubihty in the mbber means that only small quantities of antioxidants can be dissolved without producing a bloom. As an example, N,lSf-diphenyl- phenylenediamine (DPPD) has limited use because of its poor solubihty in mbber. On the other hand, phenohc and phosphite antioxidants have high solubihty and bloom is not a problem. 

Stability. In order to have maximum effectiveness over long periods of time, an antioxidant should be stable upon exposure to heat, light, oxygen, water, etc. Many antioxidants, especially in the presence of an impurity when exposed to light and oxygen, are subject to oxidation reactions with the development of colored species. Alkylated diphenyl amines are least susceptible and the -phenylenediamine derivatives the most susceptible to direct oxidation. 

As in dry compounding, acid acceptors must be incorporated into neoprene latices because of the wide use of these latices in coating fabrics and metals. The hydrochloric acid that forms during service life has a particularly destmetive effect on coated cotton fabrics that are not adequately protected. High zinc oxide concentration (ca 15 parts) and use of 0.4 parts AJ-phenyl-AT(p-toluenesulfonyl)-/)-phenylenediamine (Aranox, Uniroyal) as an antioxidant provides adequate protection. 

Antiozonants (qv) prevent or reduce polymer degradation by the active ozone molecule. Some antioxidant compounds, such as the /)i7n7-phenylenediamines, are excellent as antiozonants (36). The protection by these compounds is thought to be either a reaction with the ozone before it can react with the surface of the mbber or an aid in reuniting chains severed by ozone (37). 

A Vinyl-2-Pyrrolidinone. Commonly called vinylpyrrohdinone or VP, Al-vinyl-2-pyrrohdinone was developed in Germany at the beginning of World War 11. It is a clear, colorless Hquid that is miscible in all proportions with water and most organic solvents. It can polymerize slowly by itself but can be easily inhibited by small amounts of ammonia, sodium hydroxide (caustic pellets), or antioxidants such as N,lSf-di-j i -butyl- -phenylenediamine. It... 

Aromatic Amines. Antioxidants derived from -phenylenediarnine and diphenylamine are highly effective peroxy radical scavengers. They are more effective than phenoHc antioxidants for the stabilization of easily oxidized organic materials, such as unsaturated elastomers. Because of their intense staining effect, derivatives of -phenylenediamine are used primarily for elastomers containing carbon black (qv). 

Ai,Af-Disubstituted- -phenylenediamines, such as A/-phenyl-Af -(l,3-dimethylbutyl)-/)-phenylenediamine [793-24-8] (10), are used in greater quantities than other classes of antioxidants. These products protect unsaturated elastomers against oxidation as well as ozone degradation (see Antiozonants). 

Antioxidants resistant to extraction by lubricants and gasoline are preferred for the stabili2ation of elastomers used in automotive appfications such as gaskets and tubing. Aromatic amine antioxidants, such as A/-phenyl-Ar-(p-toluenesulfonyl)-A-phenylenediamine [100-93-6] (37), with low solubifity in hydrocarbons, are extracted slowly from elastomers and are used for these appfications. 

Chemical antiozonants comprise the second general class of commercial antiozonants. Of the many compounds reported to be chemical antiozonants, nearly all contain nitrogen. Compound classes include derivatives of l,2-dihydro-2,2,4-trimethylquinoline, A/-substituted ureas or thioureas, substituted pyrroles, and nickel or zinc dithiocarbamate salts (see also Antioxidants). The most effective antiozonants, however, are derivatives of -phenylenediamine... 

Paraphenylene-diamine derivatives A/,N -Diphenyl-p-phenylenediamine (IV) /V,A/ -Di-p-naphthyl-p-phenylenediamine (V) Yes Yes Powerful antioxidants. Have been used in a variety of plastics materials. Tendency to bloom, bleed and stain mitigates against more extensive use. Compound (V) now withdrawn by some suppliers. 

Amongst other materials sometimes used as deactivators are, l,8-bis(salicyli-deneamino)-3,6-dithiaoctane and certain p-phenylenediamine derivatives. It is interesting to note that the last named materials also function as chain-breaking antioxidants and in part as peroxide decomposers. 

Figure lO.U. Oxidation of polyethylene in air at 105°C, Effect of adding 0.1% antioxidant on power factor. A, blank. B, /V,/V -diphenyl-p-phenylenediamine. C, 4,4 -thiobis-(6-butyl-m-cresol). D, Nonox WSP. E, N./V -di-pl-naphthyl-p-phenylenediamine... 

In the 1950s it became recognised that one type of antioxidant also often behaved as an antiozonant. These were the branched alkyl, unsubstituted aryl-/7-phenylenediamines typified by A-isopropyl-A -/ -phenylenediamine (IPPD). The mechanism of their action is still not fully understood but it is to be noted that they are often improved by being used in conjunction with small amounts of hydrocarbon waxes. 

The beta-conidendrol is incorporated as an antioxidant and is frequently referred to in the patent literature, as is also di-P-naphthyl-p-phenylenediamine for this purpose. It is claimed that in the example given above the degradation rate at 222°C is only 0.09% per minute compared with typical values of 0.6-0.8% for unesterified polymer. 

For example, using hydroxy-terminated polybutadiene as the binder, RDX as the expl, toluenediisocyanate as a co-polymer, sym-di-(2-naphthyl)-p-phenylenediamine as an antioxidant, and poly butene as the plasticizer in a wt % ratio of 12.1/42.7/5/0.2/40, a castable expl is produced. 

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