Tertiary amines ozone

Perfluorinated ethers and perfluorinated tertiary amines do not contribute to the formation of ground level ozone and are exempt from VOC regulations (32). The commercial compounds discussed above have an ozone depletion potential of zero because they do not contain either chlorine or bromine which take part in catalytic cycles that destroy stratospheric ozone (33). 

Primary amino groups are oxidized stepwise by ozone to hydroxylamine, nitroso, and nitro (54,58) tertiary amines are oxidized to amine oxides. 

Mortensen A, Skibsted LH (1998) Reactivity of p-carotene towards peroxyl radicals studied by laser flash and steady-state photolysis. FEBS Lett 426 392-396 Munoz F, von Sonntag C (2000) The reactions of ozone with tertiary amines including thecomplex-ing agents nitrilotriacetic acid (NTA) and ethylenediaminetetraacetic acid (EDTA) in aqueous solution. J Chem Soc Perkin Trans 2 2029-2033... 

An older paper <1971MI873> reported that ozonolysis of alkenes in the presence of tertiary amines resulted in the formation of aldehydes. A recent reinvestigation <20060L3199> has shown that amine oxides were responsible for this reductive ozonolysis . Indeed, pretreatment of the tertiary amines with ozone, giving rise to amine oxides, accounted for this phenomenon. A preparative method emerged, by treating the alkene (e.g., 1-decene) at 0 °C with a solution of 2% 03/02 in dichloromethane (2 equiv of ozone relative to the alkene) in the presence of an excess (about threefold molar excess) of A-methylmorpholine A-oxide, pyridine A-oxide, or l,4-diazabicyclo[2.2.2]octane A-oxide (DABCO A-oxide). Yields of aldehydes (nonanal in the above example) were 80-96%, and the excess of amine oxide ensured the absence of residual ozonide (Scheme 21). 

Like tertiary amines, tertiary phosphines are readily transformed into the corresponding oxides, phosphine oxides. Tributylphosphine in di-chloromethane is oxidized with ozone adsorbed on silica gel at -70 "C to tributylphosphine oxide in 92% yield [113]. Other oxidants used to transform phosphines into phosphine oxides are potassium peroxysulfate [205], argentic oxide [381 ], manganese dioxide [813], and barium manganate [S55] (equation 537). 

The first three tertiary amines in the aliphatic series were studied by Strecker and Baltes. The authors studied tri-n-butylamine, tri-n-hexylamine, and tri-n-heptyl-amine. Each amine was ozonated at dry ice temperature and treated with picric acid. The tri-n-butylamine oxide picrate readily deposited as crystals on standing. Although the latter two amine oxides formed oily products at first, on long standing in the refrigerator they gave crystals of the amine oxide picrates. The purified amine oxide picrates were analyzed by direct titration with perchloric acid. 

Structures I and II are reported as the main contributing forms. Meinwald (5) used these to explain the addition of ozone to certain olefins. A similar mechanism can be postulated to explain the reaction of ozone on tertiary amines ... 

The reaction of ozone with these tertiary amines is very rapid, but the addition of ozone is not stoichiometric About 1.2 to 1.7 moles of ozone per mole of the tertiary amine were used. The yields of the amine oxides, isolated as the picrates, were about 50% of theory. 

After passage through the amine solution, any unreacted ozone was absorbed in 2% potassium iodide solution contained in a gas washing bottle. The volume of the ozonated oxygen, passed through the solution and stripped of ozone by the amine solution or potassium iodide solution, was measured with a wet-test meter. The reaction of ozone with tertiary amines was so rapid that at an ozone flow of 56 mg. per minute no excess ozone appeared in the potassium iodide trap during the reaction. The addition of ozone was stopped when the potassium iodide showed the yellow color due to iodine. 

Ozone is being promoted for use in the conversion of tertiary amines to amine oxides, of a-pinene to pinonic and pinic acids, of olefins to ozonides and these in turn to aldehydes and oxy-peroxides, of sulfides to sulfoxides and sulfones, and of various other organic substances. Such reactions are of practical interest in drug manufacture, and several drug companies are now commercially using ozone in their manufacturing operations, specifically in oxidation of sterols in hormone syntheses. 

The best known of these is the ozonation of tertiary amines to amine oxides (II) (i). Henbest and Stratford (11) and Shulman (17) have shown that competing with this is an ozone attack on the alpha position of an alkyl side chain to produce various decomposition products of III. Henbest (11) showed that amine oxide formation is favored in chloroform and methanol, while side chain oxidation is predominant in hydrocarbon solvents. Also of considerable interest are the reported conversions, during ozonation, of phenylenediamines to Wursters salts (VII) (8, 14), of liquid ammonia to ammonium ozonate (VA) at a low temperature 18), and of amines to amine hydrochlorides (VB) in chlorinated hydrocarbon solvents 17, 19), Finally, an early report states that azobenzene and quinone are obtained upon ozonation of aniline (15). 

The compound B formed must be, then, either a tertiary amine or an alkene. Its molecular formula does not contain "N (for nitrogen), which means it must be an alkene. In addition, the fact that B was cleaved into two products by ozone, acid, and zinc indicates the present of a double bond, for these reagents are the basis for the ozonolysis reaction, which cleaves compounds with double bonds into aldehydes and ketones. 

Ozonation of Heteroatoms. Phosphines are converted to phosphine oxides and phosphites to phosphates by ozone. These reactions are quite general and a wide range of sub-stitutents can be tolerated. Phosphine oxides also can be produced by the ozonation of alkylidenetriphenylphosphoranes or of thio- or selenophosphoranes. Organic sulfides are converted to sulfoxides and sulfones by ozonation. Tertiary amines are converted to amine oxides, while nitro compounds can be produced in modest yields by ozonation of primary amines. This preparation of nitroalkanes compares well with alternate approaches using peroxides, peroxy acids, permanganate, or Monoperoxysulfuric Acid, but ozonation on silica gel has proven to be superior (see Ozone-Silica Get). Selenides are converted to selenoxides by ozone and this reaction is often used to achieve overall production of unsaturated carbonyl compounds. An example is shown in eq 25. ... 

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." ... 

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