Esters peroxy

Ethyl peracetate was the first ester of a peroxy acid, and was characterized by Baeyer and Villiger in 1901. Kinetic studies of perester decomposition were reported by Blomquist and Ferris in 1951, and in 1958 Bartlett and Hiatt proposed that concerted multiple bond scission of peresters could occur when stabilized radicals were formed (equation 46). As noted below (equation 57), polar effects in perester decomposition are also significant. 

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ASTM Standard E 1228—88, "Standard Test Method for Peroxy Esters-Catalyzed lodometric Procedure," in Ref. 253. 

The acids are converted to peroxy esters for use as polymerization initiators. The metal salts are used as driers in paint formulations (see Carboxylic acids, TRIALKYLACETIC ACIDS). 

Hydroperoxides Organomineral Hydroperoxides a-Oxy and a-Peroxy-Hydroperoxides and Peroxides Ozonides Peroxides Peroxy Acids Diacyl Peroxides Peroxy Esters and Poly Peroxides... 

Reaction between Grignard reagents and tert-butyl peroxy esters... 

Consider the case of the production of peroxy esters (e.g. tert-buty] peroxy 2-ethyl hexanoate), based on the reaction between the corresponding acid chloride and the hydroperoxide in the presence of NaOH or KOH. These are highly temperature sensitive and violently unstable, and solvent impurities are detrimental in their applications for polymerization. Batch operations to produce even 1000 tpa will be unsafe. A continuous reactor can overcome most of the problems and claims have been made for producing purer chemicals at lower capital and operation cost the use of solvent can be avoided. Continuous reactors can produce seven to ten times more material per unit volume than batch processes. Since the amount of hazardous product present in the unit at any given time is small, protective barrier walls may be unneccessary (Kohn, 1978). 

Several catalytic systems based on copper can also achieve allylic oxidation. These reactions involve induced decomposition of peroxy esters (see Part A, Section 11.1.4). When chiral copper ligands are used, enantioselectivity can be achieved. Table 12.1 shows some results for the oxidation of cyclohexene under these conditions. 

Shibasaki et al. have reported a new approach to a,/3-epoxy esters the epoxidation of cv. j-unsaturated carboxylic acid imidazolides with a La(OPr )3, BINOL, Ph3As=0, and TBHP system provides epoxy-peroxy-esters (41), which are generated in situ from the intermediary epoxy acid imidazolide and converted to the corresponding methyl ester (42) upon treatment with methanol (Scheme 27).134... 

DSC can be used effectively in the isothermal mode as well. In this case, the container with the sample is inserted into the DSC preheated to the desired test temperature. This type of experiment should be performed to examine systems for induction periods that occur with autocatalytic reactions and with inhibitor depletion reactions. (Reactions with induction periods can give misleading results in the DSC operated with increasing temperature scans.) Autocatalytic reactions are those whose rates are proportional to the concentration of one or more of the reaction products. Some hydroperoxides and peroxy esters exhibit autocatalytic decomposition. Inhibitor depletion can be a serious problem with certain vinyl monomers, such as styrene and acrylic acid, that can initiate polymerization at ambient temperatures and then selfheat into runaways. Isothermal DSC tests can be used to determine a time to runaway that is related to the inhibitor concentration. 

Some unstable peroxy esters are also reported. The reaction of pentaphenylphosphine with tert-butylhydroperoxide or silicon and germanium hydroperoxides gave the corresponding peroxy derivatives 56, which cannot be isolated (equation 91). 

Since the first synthesis of the peroxyphosphoms ester 66 °, considerable efforts have been made to characterize the expanding chemistry of organophosphorus peroxy esters. Later, unsymmetrical phosphorus peroxides, such as peroxyphosphates 67 , peroxyphos-phonates 68 and peroxyphosphinates 69 , were reported. They can be prepared by the reactions of the chlorides and a tertiary carboxylic acid in the presence of base. 

Peroxy esters 67 were prepared in situ by the reaction of phosphonochloridate and terf-butyl hydroperoxide in diethyl ether. The peroxy ester 67 (R = Ph) is stable for several days at 5 °C in diethyl ether. Most peroxyphosphates 67 with an RO group other than ferf-butylperoxy are unstable even for short periods . This synthetic method was successfully applied for synthesis of ring peroxyphosphates 70 and 71 as colorless oils. They are very unstable and decompose at 25 °C to yield polymeric products and volatile side products . ... 

Interestingly, the fluorine-containing peroxy ester of phosphoms 73 was prepared in 87% yield by the condensation of /r-oxo-bis(phosphonyl difluoride) (P2O3F4) and triflu-oromethyl hydroperoxide (equation 100) . ... 

Turning back to the stereochemistry of the three diastereoisomeric peroxy esters 69, we now can assign stereochemistry by the H-NMR shifts, as was done in Table 8, p. 49, in accordance with all other observations. 

Copper-catalyzed687-689 or photochemical690 reaction of alkenes with peroxy-esters, usually with tert-butyl peracetate (or rm-BuOOH in acetic acid), may be used to carry out acyloxylation or the synthesis of the corresponding allylic esters in good yields. In contrast to the oxidation with Se02, preferential formation without rearrangement of the 3-substituted esters takes place from terminal alkenes 691... 

Peroxy esters are a known class of compounds. Fluorinated peroxy esters can be prepared208,209 by the reaction of the hydroperoxides with fluorinated acyl chlorides or acid anhydrides in the presence of pyridine as the base. It has also been demonstrated210 that trifluoromethyl... 

Tetrahydroperoxycyclohexane Tetraacetate. C1SH28012 mw 436.46 OB to C02 —139.30% rhombic plates (from ethanol) mp 144—45° (decompn, then deton). Prepn is by reacting (caution) cyclodecandione (tetra) peroxide with ethanoyl chloride. The peroxy ester explds on gentle rubbing Refs 1) Beil, not found 2) R. Criegee H. Dietrich, Ann 560, 135-41 (1948) CA 43, 6189 (1949)... 

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