Oxides tertiary

The addition of acetic acid (0.5 equiv. to the substrate) to the catalyst system led to increased activity (doubling of yield) by maintaining the selectivity with 1.2 equiv. H2O2 as terminal oxidant. Advantageously, the system is characterized by a certain tolerance towards functional groups such as amides, esters, ethers, and carbonates. An improvement in conversions and selectivities by a slow addition protocol was shown recently [102]. For the first time, a nonheme iron catalyst system is able to oxidize tertiary C-H bonds in a synthetic applicable and selective manner and therefore should allow for synthetic applications [103]. 

The mechanism of H02 formation from peroxyl radicals of primary and secondary amines is clear (see the kinetic scheme). The problem of H02 formation in oxidized tertiary amines is not yet solved. The analysis of peroxides formed during amine oxidation using catalase, Ti(TV) and by water extraction gave controversial results [17], The formed hydroperoxide appeared to be labile and is hydrolyzed with H202 formation. The analysis of hydroperoxides formed in co-oxidation of cumene and 2-propaneamine, 7V-bis(ethyl methyl) showed the formation of two peroxides, namely H202 and (Me2CH)2NC(OOH)Me2 [16]. There is no doubt that the two peroxyl radicals are acting H02 and a-aminoalkylperoxyl. The difficulty is to find experimentally the real proportion between them in oxidized amine and to clarify the way of hydroperoxyl radical formation. 

N-Oxides, sulfoxides, sulfones.2 The hydroperoxide oxidizes tertiary amines to N-oxidcs (60 95% yield) and sulfides to sulfoxides (1 equivalent) or to sulfones (2 equivalents). 

Primary and secondary alcohols can be oxidized, Tertiary alcohols cannot be oxidized on the MCAT. In organic chemistry, you can use the following rule to determine if a compound has been oxidized or reduced ... 

The Ru(II)/ROOH system can also be used to oxidize tertiary amines. The intermediate iminium ion is formed, as described earlier for secondary amines, and can be trapped by nucleophiles. Thus, the ruthenium-catalysed oxidation of tertiary amines with hydrogen peroxide in methanol can be performed to give the corresponding a-methoxyamines with high efficiency as illustrated in Fig. 24 [ 137]. Another example is the selective demethylation of tertiary amines in methanol with a combination of Ru(II) and H202, followed by hydrolysis of the intermediate a-methoxylated amines. For example, the methoxylation of N,N-dimethyl-p-toluidine followed by treatment with 2 N HC1 solution gave N-methyl-p-toluidine in 75% yield (Eq. 35) [137]. 

Pyridine and Dipyridyl N-Oxides Tertiary Phosphine Oxides... 

Aqueous or alcohol solutions of amine oxides are normally obtained by oxidizing tertiary amines with either hydrogen peroxide or a peracid.4 For example, N,N-dimethyldodecyl-amine oxide has been prepared by treating N,N-dimethyl-dodecylamine with aqueous hydrogen peroxide.5 The procedure illustrated in this preparation permits the oxidation of tertiary amines with /-butyl hydroperoxide in organic solvents under relatively anhydrous conditions.6 In this procedure the reaction time is short and the method is as convenient as the use of aqueous hydrogen peroxide or a peracid as the oxidant. Furthermore, isolation of the anhydrous amine oxide is often relatively simple. 

If the intermediates are treated with mercury(II) chloride to induce a second migration from boron to carbon and then oxidized, tertiary alcohols can be obtained. The very hindered cyclohexyldicyclopentylcarbinol was prepared in this way in 80% yield from 1 (R = cyclohexyl) and dicyclopentylhexylborane. ... 

An alternative oxidation using O2 and a RuCls catalyst converted pyridine to pyridine A-oxide. Bromamine-T and RuCls in aq. acetonitrile also oxidizes pyridine to the A-oxide. Tertiary amines are oxidized to the A-oxide with O2 and Fe203 in the presence of an aliphatic aldehyde. " Oxygen and a cobalt-Schiff base complex also oxidzes tertiary amines, including pyridine. ... 

Methyl(trifluoromethyl)dioxiiane (TFDO), prepared from 1,1,1-trifluoroacetone and KHSOg, is more reactive than DMDO by a factor of 600. In addition to facile epoxidation of alkenes, TFDO can be used to regioselectively oxidize tertiary over secondary C-H bonds via an oxenoid (butterfly) mechanism. ... 

Some other metal salts and other reagents which have been used to oxidize tertiary amines to enamines include palladiumfll) chloride copper(II) chloride , copperfi) chloride with oxygen , iodine, iodine pentafluoride , chlorine dioxide S permanganate ion , manganese dioxide , AT-bromosuccinimide , benzoyl peroxide , quinones and azodiformate . ... 

Oxidations. Tertiary cyclopropanols undergo oxidative ring opening on exposure to CAN, an added salt provides anion to functionalize the emerging ethyl terminus. ... 

None of the PAs tested resulted toxic to the chrysomelid L. decemlineata. Oreina (Chrysomelidae) beetles are able to take up plant alkaloid N-oxides and eliminate tertiary PAs, but are unable to N-oxidize tertiary PAs [55, 67, 68]. Similarly, L. decemlineata adults could eliminate tertiary PAs efficiently enough to avoid poisoning. 

DMSO need not be the solvent, however, and cosolvents such as ethyl acetate often give better results. Many applications are possible due to the neutral oxidizing conditions and lack of side reactions, and a variety of functionalized substrates containing alcohol moieties have been oxidized. Tertiary alcohols are, of course, resistant to Moffatt oxidation and dehydration has been observed in such systems, 10 giving the alkene and regenerating DMSO.i O Some steroidal allylic alcohols dehydrate to a heteroannular diene under these condi-... 

Filled liquid neoprene sealants are cured at room temperature by the addition of lead oxide, tertiary amines or epoxy resins. Neoprene sealants covered by a top coat of white chlorosulfonated polyethlyene are being used on solar collectors.21 Mixtures of carboxyl terminated acrylonitrile elastomers (CTBN) and liquid epoxy resins cure readily at room temperature in the presence of bis phenol A and amines.22 Coal tar-epoxy resin, two component epoxy resin, and epoxypolyester resin systems have been used as sealants.22... 

Other oxidoreduction examples of inversion are the sulfoxide/sulfide and N-oxide/tertiary amine equihbria. Chiral sulfoxides (e.g., sulindac, flosequinan, pantoprazole) that contain tricoordinated sulfur atoms or tertiary amine N-oxides are first reduced by reductases to the corresponding achiral sulfides or tertiary amines, respectively. The reduced metabohtes are nthen reoxygenated by monooxygenases back to the parent compound, which can result in an altered ratio of the two enantiomers or epimers. 

Besides the unusual regioselectivity of alkane oxidation (tertiary C-H bonds are less reactive than secondary C-H bonds ) another interesting feature of the reactive species in Gif-reactions is the unusual relative reactivity of alkane C-H bonds compared with some other readily oxidizable compounds such as alcohols, thiols and triphenylphosphine The explanation of such behavior is not clear so far. 

Oxidation by these reagents of the various primary and secondary alcohols we have been making in this chapter takes us to a higher oxidation level. Oxidation of primary alcohols gives aldehydes and then carboxylic acids, while oxidation of secondary alcohols gives ketones. Note that you can t oxidize tertiary alcohols (without breaking a C—C bond). 

Anionic Anionic polymerization is widely used. Initiators alkali metal oxides, tertiary amines, tertiary phosphines, organometaUic compounds, etc. Chloral is mixed with an anionic initiator above the threshold temperature, for bulk polymerization, and the mixture is then cooled (usually to 0°C under quiescent conditions). Thus, jxjlychloral pieces of desired shape can be prepared. (2-4)... 

DMP with high purity by the original procedure therefore, a few modifications have been suggested. In addition, DMP has been successfully used in the syntheses of polycyclic heterocyclesand in the removal of thioketals and thioacetals. It should be mentioned that other hypervalent iodine compounds can be used as oxidants as well, especially for the o-iodoxybenzoic acid (IBX), the precursor to DMP, which can oxidize tertiary cyclic allyl alcohol into O, y0-unsaturated cyclic ketones and secondary amines into imines and can convert epoxides or aziridines into corresponding of-hydroxy ketones or Q -amino ketones. 

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