Diphenyl-phenylenediamine

ASTM Standard E 440-72, "Standard Test Method for Traces of Peroxides in Organic Solvents With N,N -Diphenyl-/-Phenylenediamine," in Ref. 253. 

The second major route to diarylamiaes is the condensation of an aromatic amine with a phenol. Aniline [62-53-3] phenol [108-95-2] and 3.5% phosphoric acid at 325°C gives a 50% yield of DPA (23). Apparently, this reaction iavolves the addition of aniline to the keto form of the phenol. Thus, naphthols and hydroquiaone are more reactive and give higher yields of product. This is the preferred route to A/-phenyi-2-naphthyiamiQe, 4-hydroxydiphenyiamiQe, and diphenyl- -phenylenediamine (24). 

The N,]S7 - diphenyl- -phenylenediamine is prepared by heating hydroquiaone with aniline ia the presence of phosphoric acid (29). A[,Ar-di-2-naphthalenyl-/)-phenylenediamiQe is made from -phenylenediamine and 2-naphthol. 

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. 

In a hood, behind a safety shield, in a 250-ml flask fitted with a thermometer, a fine capillary tube connected to a drying tube for an air bleed, and a distillation column packed partially with copper cloth (see above) topped with a spray trap and a total reflux, partial take-off distillation head are placed 100 ml of glacial acrylic or methacrylic acid and 1 gm of A,N -diphenyl-/ -phenylenediamine or phenothiazine. 

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