Tert-Amyl peroxides

The most important radical initiators used for polymer polyol synthesis are azoderivatives, such as azoisobutyrodinitrile (AIBN) [1, 3,13, 22]. Other initiators used successfully are peroxides (tert-amyl peroxides are very efficient), hydroperoxides and percarbonates, but the half life has to be lower than two minutes, at the polymerisation temperature (115-125 °C) [23-28]. 

Di(tert-butyl) peroxide Di(tert-amyl) peroxide Dicumyl peroxide... 

Polymerisation Aryl-Alkylperoxides Di(tert.amyl)peroxide Liquid, techn. pure... 

Table 15 shows that peroxyester stabiUty decreases for the alkyl groups in the following order tert — butyl > tert — amyl > tert — octyl > tert — cumyl > 3 — hydroxy — 1,1 dimethylbutyl. The order of activity of the R group in peroxyesters is also observed in other alkyl peroxides. Peroxyesters derived from benzoic acids and non-abranched carboxyUc acids are more stable than those derived from mono-a-branched acids which are more stable than those derived from di-a-branched acids (19,21,168). The size of the a-branch also is important, since steric acceleration of homolysis occurs with increasing branch size (236). Suitably substituted peroxyesters show rate enhancements because of anchimeric assistance (168,213,237). 

Aldehydes are transformed into carboxylic acids by hydrogen peroxide and its derivatives. In the presence of selenium dioxide as a catalyst, acrolein is oxidized to acrylic acid in 90% yield on treatment with a 12% solution of hydrogen peroxide in tert-amyl alcohol at 40 C for 3 h [725]. Methacrolein is converted into methacrylic acid by 90% hydrogen peroxide in the presence of selenium dioxide at 60 °C [725] or by peroxysulfuric acid 200 (equation 346). 

Common initiators tert-octyl peroxyneodecanoate, dicyclohexyl peroxydicaibonate, tert-butyl peroxyneodecanoate, benzoyl peroxide, 2,2 -azobisbutylnitrile, tert-amyl per-oxypivalate, dilauroyl peroxide... 

Approximately 15% of the photolysed hydroperoxide groups are reported to undergo a )5-scission reaction [383]. Several low molecular peroxides such as tert-amyl hydroperoxide, di-tcrf-butyl peroxide, 1,1-dienonylethyl hydro-... 

Practically anhydrous hydrogen peroxide as a solution in tert-buty or /er/-amyl alcohol is prepared by azeotropic removal of water by distillation of a mixture of 35% hydrogen peroxide in the alcohol at 50 °C and 50 mm of Hg until no more water distills. A solution containing 12% of hydrogen peroxide in tert-amy alcohol is thus obtained [725]. 

Trivial name Acetaldehyde Acetamide Acetic acid Acetic anhydride Acetoacetic acid Acetone Acetonitrile Acetophenone Acetyl chloride Acetylene Acrolein Acrylamide Acrylic acid Acrylonitrile Adipic acid Amyl acetate Amyl alcohol tert-Amy alcohol Aniline Azelaic acid Benzoic acid Benzoyl peroxide Benzyl alcohol Bisphenol A... 

---