Lithium ozonide

The relevant properties of peroxide and superoxide salts are given in Table 4 (see Peroxides and peroxide compounds, inorganic). Potassium peroxide is difficult to prepare and lithium superoxide is very unstable. The ozonides, MO3, of the alkah metals contain a very high percentage of oxygen, but are only stable below room temperature (see Ozone). 

Die Reduktion wird (z.B. auch mit Lithium-3 und Natriumboranat3-5) entweder nach Isolierung des Ozonids oder einfacher durch Umsetzen der ozonisierten Olefin-Losung mit dem Reduktionsmittel (nach Ausblasen des Ozons) durchgefiihrt3,4,6. 

Why do some of the alkali metals form oxides, while others form peroxides when they burn in the air How does the stability of the alkali metal oxides and peroxides change (from lithium to cesium) when heated Why is the formation of peroxides and also of ozonides the most characteristic of the alkali metals ... 

Catalytic hydrogenation114-116 also leads to carbonyl compounds, acids being formed in a side reaction.110 Reduction of the ozonides with lithium aluminum hydride117 119 and with sodium borohydride119 yields alcohols. 

The first step, a 1,3-dipolar addition, results in the formation of a primary ozonide (1 equation 6). This intermediate then opens to give a carbonyl and a zwitterion that can recombine to give the more stable normal ozonide (2 equation 7). Reduction of (2), without isolation, by lithium aluminum hydride, diborane or sodium borohydride dten gives either primary or secondary alcohols, depending on the nature of starting alkene (equation 8). 

Ozonides are rarely isolated [75, 76, 77, 78, 79], These substances tend to decompose, sometimes violently, on heating and must, therefore, be handled with utmost safety precautions (safety goggles or face shield, protective shield, and work in the hood). In most instances, ozonides are worked up in the same solutions in which they have been prepared. Depending on the desired final products, ozonide cleavage is done by reductive or oxidative methods. Reductions of ozonides to aldehydes are performed by catalytic hydrogenation over palladium on carbon or other supports [80, 81, 82, S3], platinum oxide [84], or Raney nickel [S5] and often by reduction with zinc in acetic acid [72, 81, 86, 87], Other reducing agents are tri-phenylphosphine [SS], trimethyl phosphite [89], dimethyl sulfide (DMS) [90, 91, 92], and sodium iodide [93], Lithium aluminum hydride [94, 95] and sodium borohydride [95, 96] convert ozonides into alcohols. 

Dienes react with ozone at one or both double bonds to give carbonyt compounds. When 1,3-cyclohexadiene is dissolved in dichloromethane at -78 °C and treated with 1.5 mol of ozone in dichloromethane solution and the resulting ozonide is stirred overnight at 0 °C with dimethyl sulfide, 2-hexenedial is obtained in 67% yield. If, on the other hand, an excess of ozone is passed through a solution of 1,3-cyclohexadiene at -78 °C until a blue color appears, both double bonds are ozonolyzed, and a 70% yield of 1,4-butanediol is obtained by reducing the reaction mixture with lithium aluminum hydride (equation 138) [92]. More substituted double bonds react with ozone preferentially. 

Thus, on heating 3-chlorostigmast-22-en-6-one with potassium hydroxide in ethanol at reflux, 3,5-cyclostigmast-22-en-6-one (3) was obtained in 90% yield. Then reduction with lithium aluminum hydride gave e/>/-stigmasterol in essentially quantitative yield. This latter compound was ozonized in chloroform solution and the ozonide treated with acetic acid to give 3-hydroxy-5-bisnorcholenic acid. ... 

PLATINUM (7440-06-4) Pt Powdered form is highly reactive catalyst, and may cause fire and explosions on contact with many substances including oxidizers, acetone, strong acids, finely divided aluminum, dioxygen difluoride, ethyl alcohol, hydrazine, hydrogen peroxide, lithium, methyl hydroperoxide, nitrosyl chloride, ozonides, peroxymonosulfliric acid, red phosp] oms. Incompatible with ammonia, arsenic, chlorine dioxide, hydrogen, methyl hydroperoxide, selenium, tellurium, vanadium dichloride. 

Scheme 7 Ozonization of alcohol (79) followed by treatment of the ozonide with Me2S afforded hydroxy ketones (80), whose acetate derivatives was converted to indenone (83). Hydroxy ketone (84), prepared from (83) was converted to compound (85), whose acetate on oxidation gave diol (87). Its transformation to butenolide (88) was easily carried out. This on oxidation and reduction produced hydroxy phytuberin lactone (89), which was converted to its sulfonyl derivative. Reductive removal of the sulfonate group yielded the cyclopropane derivative (91), which on subjection to reductive cleavage with lithium in liq. NH3 yielded phyberin lactone (92) and deacetyl phytuberin lactone (93)...

Reducing agents can be used, but most convert the ozonide to an alcohol rather than to a carbonyl. Reduction of the ozonide with lithium aluminum hydride or sodium borohydride generates the alcohol products, as expected, by further reducing the intermediate carbonyl products. It is noted that 1 mol of L1A1H4 is required per mole of ozonide and the temperature is usually maintained below The most... 

C.ii. Ozonides. Ozonolysis is a powerful method for cleaving alkenes to carbonyl products (sec. 3.7.B). Ozonolysis of alkenes initially generates an ozonide that can be reduced by a variety of reagents. Dimethyl sulfide or zinc in acetic acid are the most common reagents for the reduction of an ozonide to an aldehyde or ketone. Reduction of the ozonide with the more powerful lithium aluminum hydride, however, gives direct conversion to the alcohol. 

Reaction of 5ab with Methyllithium. Ozonide (5ab) for Methyl-lithium Reduction. This substance was prepared using 40.61% 0-water (YEDA) to generate acetaldehyde containing 21.05% 0 according to the procedure described above. 

A solution of 110 mg. (0.83 mmoles) of 5ab in ether was added slowly to a solution of methyllithium (10% excess, Foote Chemical) in ether. The highly exothermic reaction was cooled in a room temperature water bath. Methane (39 ml.), ether vapor, and possibly carbon dioxide were collected [theoretical for proton abstraction reduction 19 ml. of methane]. After addition of ozonide was complete, the reaction was worked up in the same manner as the lithium aluminum hydride reduction. GPC analysis of the crude mixture revealed isopropyl alcohol (9) (>—60% by GPC standard) and 3-methyl-2-butanol (10) —60%). Methanol is normally produced in approximately the same yield (—60% ) as 9 and 10. We were unable to collect a sufiicient quantity from the labeling experiment for mass spectral analysis. Product identification was based on GPC retention times and by comparison of infrared spectra with those of authentic compounds. Mass spectral results were as follows isopropyl alcohol- assay 11.88% oxygen-18 3-methyl-2-butanol (10) assay 2.45%. 

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