Peroxide yield

A process to produce propylene by VPO of propane was patented in the former USSR in 1987 (146). Similar processes have the potential to coproduce hydrogen peroxide. Yields of hydrogen peroxide as high as 1 mol/mol propylene produced have been reported with 60—70% propylene selectivity (147). 

Hydrolysis and perhydrolysis of diacyl peroxides yields peroxycarboxyhc acids. Carbanions react by displacement on oxygen ... 

Nitrated fluoro compounds are synthesized by electrophilic (NOz+), radical (NO2 ), or nucleophilic (NO2-) methods Indirect nitration routes can suppress the side reactions associated with severe reaction conditions and some nitration reagents Novel fluoronitro compounds, unobtainable by direct nitration, can also be pre pared For example, the nitration of (2-fluoro-2,2-dinitroethoxy)acetaldoxime followed by oxidation of the nitroso intermediate with hydrogen peroxide yields 2-fluoro-2,2-dinitioethyl 2,2-dinitroethyl ether [f] (equation 1)... 

Treatment of an or.jS-unsaturated ketone with basic aqueous hydrogen peroxide yields an epoxy ketone. The reaction is specific to unsatnrated ketones isolated alkene double bonds do not react. Propose a mechanism. 

The mechanism of activation is believed to be as follows. In an alkaline medium, hydrogen peroxide yields the perhydroxide anion (Scheme 10.22), which reacts with TAED (10.86) to form diacetylethylenediamine (10.87) and the peracetate anion (10.88) as in Scheme 10.30 [244]. At pH 8-9, the peracetate anion is in equilibrium with free peracetic acid, as in Scheme 10.31 [244]. The peracetic acid reacts with the peracetate anion to form nascent oxygen which is the active bleaching agent, as in Scheme 10.32 [244]. Further possible activators suggested by Kleber [244] include ... 

Polynuclear aromatic hydrocarbons can be oxidized photolytically with the formation of cyclic peroxide. For example, anthracene is photooxidized to peroxide with the quantum yield 0 = 1.0 [205], The introduction of quenchers lowers the peroxide yield. 

Various hydroxyl and amino derivatives of aromatic compounds are oxidized by peroxidases in the presence of hydrogen peroxide, yielding neutral or cation free radicals. Thus the phenacetin metabolites p-phenetidine (4-ethoxyaniline) and acetaminophen (TV-acetyl-p-aminophenol) were oxidized by LPO or HRP into the 4-ethoxyaniline cation radical and neutral V-acetyl-4-aminophenoxyl radical, respectively [198,199]. In both cases free radicals were detected by using fast-flow ESR spectroscopy. Catechols, Dopa methyl ester (dihydrox-yphenylalanine methyl ester), and 6-hydroxy-Dopa (trihydroxyphenylalanine) were oxidized by LPO mainly to o-semiquinone free radicals [200]. Another catechol derivative adrenaline (epinephrine) was oxidized into adrenochrome in the reaction catalyzed by HRP [201], This reaction can proceed in the absence of hydrogen peroxide and accompanied by oxygen consumption. It was proposed that the oxidation of adrenaline was mediated by superoxide. HRP and LPO catalyzed the oxidation of Trolox C (an analog of a-tocopherol) into phenoxyl radical [202]. The formation of phenoxyl radicals was monitored by ESR spectroscopy, and the rate constants for the reaction of Compounds II with Trolox C were determined (Table 22.1). 

Oxidation of the fused thiazine 192 by hydrogen peroxide yielded the cyclic sulfone 193 <2004T4361>. Oxidation of the fused thiazaphosphole 195 was accomplished by /-butyl peroxide to yield 196 in relatively low yield (33%), whereas reaction of 194 with elemental sulfur yielded the P-sulfide 195 in 62% yield <1994PS59>. 

Oxidation of 3,6-diamino-1,2,4,5-tetrazine (198) with oxone in the presence of hydrogen peroxide yields 3,6-diamino-l,2,4,5-tetrazine-2,4-dioxide (201) (LAX-112). The same reaction with 90 % hydrogen peroxide in trifluoroacetic acid yields 3-amino-6-nitro-1,2,4,5-tetrazine-2,4-dioxide (202). Treatment of 3,6-diamino-1,2,4,5-tetrazine (198) with 2,2,2-trinitroethanol and 2,2-dinitro-2-fluoroethanol generates the Mannich condensation products (203) and (204) respectively. 

The alkylation of quinoline by decanoyl peroxide in acetic acid has been studied kineti-cally, and a radical chain mechanism has been proposed (Scheme 207) (72T2415). Decomposition of decanoyl peroxide yields a nonyl radical (and carbon dioxide) that attacks the quinolinium ion. Quinolinium is activated (compared with quinoline) towards attack by the nonyl radical, which has nucleophilic character. Conversely, the protonated centre has an unfavorable effect upon the propagation step, but this might be reduced by the equilibrium shown in equation (167). A kinetic study revealed that the reaction is subject to crosstermination (equation 168). The increase in the rate of decomposition of benzoyl peroxide in the phenylation of the quinolinium ion compared with quinoline is much less than for alkylation. This observation is consistent with the phenyl having less nucleophilic character than the nonyl radical, and so it is less selective. Rearomatization of the cr-complex formed by radicals generated from sources other than peroxides may take place by oxidation by metals, disproportionation, induced decomposition or hydrogen abstraction by radical intermediates. When oxidation is difficult, dimerization can take place (equation 169). 

Reduction of (S)-pinanediol [phenyl(chloro)methyl]boronate with commercially available lithium triethylborodeuteride yields a chirally deuterated benzylboronic ester. Deboronation of the deuterated benzylboronic ester with hydrogen peroxide yields chirally deuterated benzyl alcohol in 96-98% ee70. The conversion of the deuterated benzylboronic ester to chirally deuterated phenylalanine has also been accomplished (Section 1.1.2.1.4.2.). 

The reactions of dioxygen have been amply documented The reduction can occur by a one-, two- or four-electron transfer reaction, the first of which is energetically unfavorable. The one-electron reduction of hydrogen peroxide yields the extremely reactive hydroxyl radical (Scheme 1). 

It can be shown by 13C Fourier transform NMR spectroscopy at — 78 °C that a six-membered peroxide is an intermediate which disappears completely on warming, with formation of the observed reaction products. The extrusion of nitrogen from the six-membered peroxide yielded the four-membered peroxide (equation 25) accompanied by light emission103. 

Scheme 9.4). The insertion of hydroxonium ion formed from protonated hydrogen peroxide yields the corresponding tertiary carbocation (14) in different pathways 14 then undergoes further transformations to give 15. 

With respect to the untreated Reactor I, the hydrogen peroxide yield was very small, and that of methane, ethylene, carbon monoxide, and acetaldehyde was large. The small ratio of hydrogen peroxide to propylene is possibly caused by the successive decomposition of hydrogen peroxide once formed. With aged Reactor II, the yield of hydrogen peroxide and methanol increased, while that of methane, ethylene, and carbon monoxide decreased significantly. 

Results are shown in the last two columns of Table I. Hydrogen peroxide yield and its mole ratio to propylene were markedly larger with Reactor VII than with Reactor VI. Thus, the decomposition of the hydrogen peroxide formed is remarkably suppressed in Reactor VII. Yields of ethylene, carbon dioxide, and formaldehyde were larger in Reactor VI than VII, but yields of hydrogen peroxide and methanol were low. 

Table III gives the results for each reaction temperature. The experimental data are of the runs at the optimum residence time which give the maximum hydrogen peroxide yield at the respective temperature.

In a quartz reactor both the amount of condensed liquid and the hydrogen peroxide concentration were larger than those with stainless steel reactor. For example the hydrogen peroxide yield of Run 340 was about 25% higher than that of Run 54. 

The evidence supplied by the method of formation and the occurrence of isomerism as to analogous structures for the thiosulphates and selenosulphates, is amplified by the chemical behaviour of the potassium alkyl selenosulphates, obtained by treatment of potassium selenosulphates with alkyl halides.1 These, on electrolytic reduction and also on oxidation with hydrogen peroxide, yield the corresponding di-selenides (compare the thiosulphates, p. 203). The structure of the selenosulphates therefore involves a selenium atom directly attached to... 

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