DI ALKYL PEROXIDE

Explosives have also been prepd from alkylated compds by methods other than nitration. For instance, some explosive primary and secondary di alkyl peroxides were obtained by interaction of alkylmethane sulfonate and hydrogen peroxide(Ref 4,... 

CYCLIC PEROXIDES, DIACYL PEROXIDES DI ALKYL PEROXIDES, X/-DI(BENZOYLPEROXY)ARYL1ODINES DIFLUOROAMINO COMPOUNDS, DIFLUOROAMINOPOLYNITROAROMATIC COMPOUNDS... 

Solvent dependence of for di-/-alkyl peroxides is small when compared to most other peroxide initiators. " " For di-/-butyl peroxide, is slightly greater (up to two-fold at 125 C) in protie (/-butanol, acetic acid) or dipolar aprotic solvents than in other media (cyclohexane, trielhylamine, letrahydrofuran). 

For initiation and molecular weight control in free radical polymerization of ethylene, a combination of several substances can be applied. Typically used free radical initiators belong to the classes of di-alkyl peroxides, peroxy alkyl esters, peroxy-carbonates, or di-acyl peroxides. The choice of the initiator mainly depends on its half lifetime at application temperature. To generate a more or less constant radical concentration level over a wide range of temperatures (e.g., 150-300 °C), a combination of different initiators is commonly applied. A typical mixture consists of a low and high temperature decomposing peroxide dissolved in hydrocarbons. 

Chemical Properties. Acychc di-Z f/-alkyl peroxides efftciendy generate alkoxy free radicals by thermal or photolytic homolysis. 

Because di-/ fZ-alkyl peroxides are less susceptible to radical-induced decompositions, they are safer and more efficient radical generators than primary or secondary dialkyl peroxides. They are the preferred dialkyl peroxides for generating free radicals for commercial appHcations. Without reactive substrates present, di-/ fZ-alkyl peroxides decompose to generate alcohols, ketones, hydrocarbons, and minor amounts of ethers, epoxides, and carbon monoxide. Photolysis of di-/ fZ-butyl peroxide generates / fZ-butoxy radicals at low temperatures (75), whereas thermolysis at high temperatures generates methyl radicals by P-scission (44). 

In the presence of base, di-Z f/-alkyl peroxides are stable, however primary and secondary diaLkyl peroxides undergo oxygen—oxygen bond cleavage, forming alcohols, aldehydes, and ketones (44,66) ... 

Primary and secondary dialkyl peroxides react much mote readily than di-/ fZ-alkyl peroxides (66,76). Products derived from the free radical are also produced in these reactions. 

Such copolymers of oxygen have been prepared from styrene, a-methylstyrene, indene, ketenes, butadiene, isoprene, l,l-diphen5iethylene, methyl methacrjiate, methyl acrylate, acrylonitrile, and vinyl chloride (44,66,109). 1,3-Dienes, such as butadiene, yield randomly distributed 1,2- and 1,4-copolymers. Oxygen pressure and olefin stmcture are important factors in these reactions for example, other products, eg, carbonyl compounds, epoxides, etc, can form at low oxygen pressures. Polymers possessing dialkyl peroxide moieties in the polymer backbone have also been prepared by base-catalyzed condensations of di(hydroxy-/ f2 -alkyl) peroxides with dibasic acid chlorides or bis(chloroformates) (110). 

Mesityl oxide and hydrogen peroxide react initially to form the cycHc hydroxyalkyl alkyl peroxide, a 1,2-dioxolane. Prolonged equiUbration results in formation of the cycHc di(alkylperoxyalkyl) peroxide, 3,3 -dioxybis(3,5,5-trimethyl-l,2-dioxolane) [4507-98-6] (122,138) ... 

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. 

Other unsymmetrical peroxides can be prepared by this reaction by employing other acylating agents, eg, alkyl chloroformates, organosulfonyl chlorides, and carbamoyl chlorides (210). Unsymmetrical and symmetrical di(diacyl peroxides) also are obtained by the reaction of dibasic acid chlorides directiy with peroxycarboxyhc acids or monoacid chlorides directiy with diperoxycarboxyhc acids in the presence of a base (44,187,203). 

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). 

Dioxabicyclo[2.2.1]heptane naturally assumed the role of the principal target molecule. It represented a considerable synthetic challenge, for not only is it a strained bicyclic molecule containing the weak and labile 0—0 bond, but it is also a di(secondary-alkyl) peroxide which is the most difficult type to make by classical procedures 12). New synthetic methods of exceptional mildness were clearly needed to solve this problem. In the course of the development of such techniques and from a desire to establish their scope, a variety of saturated bicyclic peroxides have been obtained in addition to 2,3-dioxabicyclo[2.2.1]heptane. The question of how substitution patterns and ring sizes affect the reactivity of bicyclic peroxides has further served to broaden interest in the subject. 

Ditellurides, 24 422 Diterpene glycosides, 24 239 Diterpenoid acids, 24 552 Diterpenoids, 24 550-555 labdane family of, 24 573 Di -ferf-alkyl peroxides, 23 439-441 as free-radical initiators, 14 288... 

TABLE 9. Rate constants for the formation of di-tertiary alkyl peroxides from tertiary alkylperoxy radicals ... 

Rust (Ref la) patented the use of this other di-c-alkyl peroxides as polymerization catalysts diesel oil additives Refs 1) Beil-not found la) W.E. Vaughan F.F. Rust, USP 2403771(1946) CA 40, 5757(1946) 2) N.A. Milas D.M. Surgenor,... 

Alkyl peroxides Di-ferf-butyl peroxide 2,5-Dimethyl-2,5-di-fcrf-butylperoxy-hexyne-3 Diisopropyl peroxide... 

Chemical Properties. Acyclic di-ferf-alkyl peroxides efficiently generate alkoxy free radicals by thermal or photolytic homolysis. Primary and secondary dialkyl peroxides undergo thermal decompositions more rapidly than expected owing to radical-induced decompositions. Such radical-induced peroxide decompositions result in inefficient generation of free radicals. 

Because di-tert-alkyl peroxides are less susceptible to radical-induced decompositions, they tire safer and more efficient radical generators Ilian primary or secondary dialkyl peroxides. They are the preferred clialkyl peroxides for generating free radicals for commercial applications. 

Dialkyl peroxydicarbonates (17) are produced by reaction of alkyl chlo-roformates with sodium peroxide. OO-Acyl O-alkyl monoperoxycarbon-ates i 8 i are obtained from tine reaction of alky] chloroformates with perox-ycarbnxylic acids in the presence of a hase. Symmetrical di (organosulfonyl) peroxides (20, R = R2l) have been prepared by the reaction of organosul-fonyl chlorides with sodium peroxide or hydrogen peroxide in the presence of a base. Acyl organosullbnyl peroxides (19) are prepared from Ihe, organosulfonyl chlorides and a metal salt of a peroxycarboxylic acid. Acetyl cyclohexanesulfonyl peroxide has been produced commercially by the sulfoxidation of cyclohexane. QjH. in the presence of acetic anhydride. 

A catalytic asymmetric oxidation of mono-, di-, and tri-substituted alkenes using a chiral bishydroxamic acid (BHA) complex of molybdenum catalyst in air at room temperature leads to good to excellent selectivity. It has been suggested that the Mo-BHA complex combines with the achiral oxidant to oxidize the alkene in a concerted fashion by transfer of oxygen from the metal peroxide to the alkene.78 The chiral BHA-molybdenum complex has been used for the catalytic asymmetric oxidation of sulfides and disulfides, utilizing 1 equiv. of alkyl peroxide, with yields up to 83% and ees up to 86%. An extension of the methodology combines the asymmetric oxidation with kinetic resolution providing excellent enantioselectivity (ee = 92-99%).79... 

---