Tertiary hydroperoxides

In summary, alkyl hydroperoxides are readily decomposed in the presence of catalytic quantities of transition metal complexes. In most cases the predominant reaction products are the corresponding alcohol and oxygen. Carbonyl compounds are formed in varying yields depending on the nature of the hydroperoxide. Tertiary alkyl hydroperoxides often decompose by a radical chain process, but non-chain radical processes as well as molecular processes which do not liberate large numbers of radicals occur frequently when secondary or primary hydroperoxides are cata-lytically decomposed. It appears that in many cases, a metal hydroperoxide complex is formed prior to decomposition. 

Tertiary A.1 1 Hydroperoxides, Product BuUetin, Atochem North America, Inc., Buffalo, N.Y., Nov. 1991. 

There are two main subclasses ofhydroperoxid.es organic (alkyl) hydroperoxides, ie, ROOH, and organomineral hydroperoxides, ie, Q(OOH), where Q is sihcon (43), germanium, tin, or antimony. The alkyl group in ROOH can be primary, secondary, or tertiary. Except for ethylbenzene hydroperoxide, only alkyl hydroperoxides are commercially important. 

Syimnetiical dialkyl peroxides have been prepared from alkyl hydroperoxides and lead tetraacetate. If tertiary dihydroperoxides are used, then cychc... 

The preparation of neopentyl alcohol from diisobutylene herein described represents an example of acid-catalyzed addition of hydrogen peroxide to a branched olefin, followed by an acid-catalyzed rearrangement of the tertiary hydroperoxide formed. In addition to neopentyl alcohol, there are formed acetone and also small amounts of methanol and methyl neopentyl ketone by an alternative rearrangement of the hydroperoxide. 

TBDMSCl, imidazole, DMF, 25°, 10 h, high yields. This is the most common method for the introduction of the TBDMS group on alcohols with low steric demand. The method works best when the reactions are run in very concentrated solutions. This combination of reagents also silylates phenols, hydroperoxides," and hydroxylamines. Thiols, amines, and carboxylic acids are not effectively silylated under these conditions. Tertiary alcohols can be silylated with the phosphoramidate... 

Organic peroxide-aromatic tertiary amine system is a well-known organic redox system 1]. The typical examples are benzoyl peroxide(BPO)-N,N-dimethylani-line(DMA) and BPO-DMT(N,N-dimethyl-p-toluidine) systems. The binary initiation system has been used in vinyl polymerization in dental acrylic resins and composite resins [2] and in bone cement [3]. Many papers have reported the initiation reaction of these systems for several decades, but the initiation mechanism is still not unified and in controversy [4,5]. Another kind of organic redox system consists of organic hydroperoxide and an aromatic tertiary amine system such as cumene hydroperoxide(CHP)-DMT is used in anaerobic adhesives [6]. Much less attention has been paid to this redox system and its initiation mechanism. A water-soluble peroxide such as persulfate and amine systems have been used in industrial aqueous solution and emulsion polymerization [7-10], yet the initiation mechanism has not been proposed in detail until recently [5]. In order to clarify the structural effect of peroxides and amines including functional monomers containing an amino group, a polymerizable amine, on the redox-initiated polymerization of vinyl monomers and its initiation mechanism, a series of studies have been carried out in our laboratory. 

In the postulated bioluminescence mechanism, firefly luciferin is adenylated in the presence of luciferase, ATP and Mg2+. Luciferyl adenylate in the active site of luciferase is quickly oxygenated at its tertiary carbon (position 4), forming a hydroperoxide intermediate (A). 

All classes of primary amine (including primary, secondary, and tertiary alkyl as well as aryl) are oxidized to nitro compounds in high yields with dimethyl dioxirane." Other reagents that oxidize various types of primary amines to nitro compounds are dry ozone, various peroxyacids," MeRe03/H202,"" Oxone ," ° tcrt-butyl hydroperoxide in the presence of certain molybdenum and vanadium compounds, and sodium perborate." ... 

C(C=0)C1 group to the precise structure (primary, secondary or tertiary) of the alkyl groups to which it is linked. However, our subsequent work with NO showed that its products are also sensitive to the alkyl structure yet in addition NO reacts with oxidized polymers to give distinctly different products from alcohol and hydroperoxide groups (see below). Consequently the COCl2 products were not explored further. 

NO Reactions. The most informative derivitization reaction of oxidized polyolefins that we have found for product identification is that with NO. The details of NO reactions with alcohols and hydroperoxides to give nitrites and nitrates respectively have been reported previously, and only the salient features are discussed here (23). The IR absorption bands of primary, secondary and tertiary nitrites and nitrates are shown in Table I. After NO treatment, y-oxidized LLDPE shows a sharp sym.-nitrate stretch at 1276 cm-1 and an antisym. stretch at 1631 cm-1 (Fig. 1), consistent with the IR spectra of model secondary nitrates. Only a small secondary or primary nitrite peak was formed at 778 cm-1. NO treatment of y-oxidized LLDPE which had been treated by iodometry (all -OOH converted to -OH) showed strong secondary nitrite absorptions, but only traces of primary nitrite, from primary alcohol groups (distinctive 1657 cm-1 absorption). However, primary products were more prominent in LLDPE after photo-oxidation. 

A very similar rearrangement takes place during the acid-catalysed decomposition of hydroperoxides, RO—OH, where R is a secondary or tertiary carbon atom carrying alkyl or aryl groups. A good example is the decomposition of the hydroperoxide (84) obtained by the air-oxidation of cumene [(l-methylethyl)benzene] this is used on the large scale for the preparation of phenol and acetone ... 

This procedure is not a domino process in its strictest definition, but since the oxidant tert-butyl hydroperoxide is added after allylation is complete, it is a very impressive and useful transformation for the rapid assembly of three contiguous stereogenic centers, including a tertiary alcohol moiety. 

The yield of the formed hydroperoxide depends on the structure of the oxidized hydrocarbon. The tertiary hydroperoxides appeared to be the most stable. Hence they can be received by hydrocarbon oxidation in high yield (see Table 1.3). 

The hydrocarbon with a tertiary C—H bond is oxidized to stable tertiary hydroperoxide. This hydroperoxide is decomposed homolytically with the formation of alcohol [82] ... 

Under the catalytic action of acid, tertiary hydroperoxide is hydrolyzed to alcohol and hydrogen peroxide [46,83]. 

Tertiary hydroperoxide is decomposed to alkoxyl and peroxyl radicals, for example [67] ... 

The traditional chain oxidation with chain propagation via the reaction RO/ + RH occurs at a sufficiently elevated temperature when chain propagation is more rapid than chain termination (see earlier discussion). The main molecular product of this reaction is hydroperoxide. When tertiary peroxyl radicals react more rapidly in the reaction R02 + R02 with formation of alkoxyl radicals than in the reaction R02 + RH, the mechanism of oxidation changes. Alkoxyl radicals are very reactive. They react with parent hydrocarbon and alcohols formed as primary products of hydrocarbon chain oxidation. As we see, alkoxyl radicals decompose with production of carbonyl compounds. The activation energy of their decomposition is higher than the reaction with hydrocarbons (see earlier discussion). As a result, heating of the system leads to conditions when the alkoxyl radical decomposition occurs more rapidly than the abstraction of the hydrogen atom from the hydrocarbon. The new chain mechanism of the hydrocarbon oxidation occurs under such conditions, with chain... 

The hydrogen bond formation decreases the frequency of the O—H bond valence vibration (see Section 4.2.3). Two configurations of tertiary hydroperoxides are known E- and Z-configurations. The activation barrier for transition from Z- to /i-configuration is found to be equal to 195 kJ mol 1 (quantum-chemical calculation [64]). 

Due to the ability of tertiary peroxyl radicals to disproportionate with the formation of alkoxyl radicals, the chain decomposition of tertiary hydroperoxides proceeds via the action of intermediate alkoxyl radicals [9,135]. 

Scheme B. Oxidation occurs as a chain reaction in scheme A. However, hydroperoxide formed is decomposed not by the reaction with free radicals but by a first-order molecular reaction with the rate constant km [3,56]. This scheme is valid for the oxidation of hydrocarbons where tertiary C—H bonds are attacked. For km 3> k i[RH] the maximum [ROOH] is attained at the hydroperoxide concentration when the rate of the formation of ROOH becomes equal to the rate of ROOH decay fl[RH](kj [ROOH][RH])l/2 km[ROOH] therefore, [ROOH]max = a2kn km 2 [RH]3. The kinetics of ROOH formation and RH consumption are described by the following equations [3],...

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