Peroxide alkyl and aryl

Acyl peroxides of structure (20) are known as diacyl peroxides. In this structure and are the same or different and can be alkyl, aryl, heterocychc, imino, amino, or fiuoro. Acyl peroxides of stmctures (21), (22), (23), and (24) are known as dialkyl peroxydicarbonates, 00-acyl O-alkyl monoperoxycarbonates, acyl organosulfonyl peroxides, and di(organosulfonyl) peroxides, respectively. and R2 ia these stmctures are the same or different and generally are alkyl and aryl (4—6,44,166,187,188). Many diacyl peroxides (20) and dialkyl peroxydicarbonates (21) ate produced commercially and used ia large volumes. 

TABLE 3. Silyl alkyl and aryl peroxides R R R Si—OOR 7 obtained according to equation 12... 

The other possible isomer, 1,4-dimethylpyrazole (and its other N-alkyl and -aryl analogues), reacted with chlorine in dichloroethane at 25-35°C to produce 5-chloro derivatives in around 70% yields (90EUP366329). 5-Aryl-3-methylpyrazoles were chlorinated by NCS at C-4 (86JHC459), as were a range of pyrazoles by chloroperoxidase in the presence of hydrogen peroxide and potassium chloride at pH 2.9. Yields of 68-83% make this latter process an improvement over some traditional chemical methods (87JHC1313). 

Alkyl and aryl peroxides display C—C—O absorption in the 1198-1176 cm-1 region. Acyl and aroyl peroxides display two carbonyl absorption bands in the 1818-1754 cm-1 region. Two bands are observed be-... 

Alkylation and Arylation of Aromatic Compounds by Peroxides Alkylation or Alkyl-de-hydrogenation... 

The parent 1,2-dithiolylium ion (4) is readily prepared by treatment of l,2-dithiole-3-thione (3b R = R = H) with hydrogen peroxide in acetic acid (65JCS32). The method may be applied to the alkyl and aryl derivatives with equal success. For cations with 3- and 5-substitution the acid catalyzed reactions of j8-dicarbonyl compounds with hydrogen disulfide or equivalent are best (80AHC(27)l5i), whereas the benzo-1,2-dithiolylium ion (172) and related compounds are best prepared by ring contraction of benzo-l,3-dithiins (171) (63LA(661)84>. 

Though oxidation with acidic hydrogen peroxide is rarely used, alkyl- and aryl-boronic acids are readily attacked with a migratory order of Bu PhCH2 > Bu > Bu" > Ph > vinyl Me. It tqqiears, therefore, that the reaction might be useful for selective oxidations as well as for oxidations of base lal e organoboranes. ... 

The effect of variation in the alkyl group of diacyl peroxides upon the rate of decomposition has been extensively investigated. For convenience the data are divided into decompositions of alkyl and aryl alkyl diacyl peroxides including benzoyl and phthaloyl peroxide for reference (Table 78), halogen containing diacyl peroxides (Table 79), unsaturated diacyl peroxides (Table 80), cycloalkyl diacyl peroxides (Table 81) and unsymmetrical diacyl peroxides (Table 82). The data pertain to first-order decompositions and the rate coefficients are represented as... 

EFFECT OF STRUCTURE ON THE THERMAL DECOMPOSITION OF ALKYL AND ARYL ALKYL DIACYL PEROXIDES (RCOjIj... 

They are especially important in the process of thermal and photodegradation of polymers. The primary photodissociation of alkyl and aryl peroxides takes place in the first absorption region. The weak RO-OR bond is disrupted ... 

Peroxides and Related Compounds.— Triphenylphosphine has been shown to react with the dioxetan (61) to give the quinquecovalent compound (62). This decomposes to give an epoxide on heating. Several peroxides and polyperoxides react with alkyl- and aryl-phosphines in the presence of water. Alcohols are... 

The dipole moments of a number of alkyl- and aryl-substituted furoxans have been recorded.139 The values fall in the range 4.6-5.5 D, for the isomers formerly assigned furoxan and peroxide structures alike. Auwers studied their optical properties,140 and other early publications detail some cryo-scopic141 and crystallographic142 measurements on furoxans and benzofuroxans. 

Amongst the simplest peroxidolytic antioxidants are the alkyl and aryl phosphites which also act as good melt stabilizers in PP (Table 1). Phosphites reduce hydroperoxides to alcohols with a 1 1 stoichiometry and are therefore referred to as stoichiometric peroxide decomposers (PD-s), Figure 5(a). In addition to their stoichiometric peroxidolytic activity, some phosphite esters also behave as catalytic peroxide decomposers (PD-c) in addition to having some chain-breaking (CB) activity ... 

---