Ozonization acetals

No compn was given. Briner Meier (Ref 2) attempted to ozonize acet in a gaseous form, bur instead of prepg an acet ozonide, they... 

No compn was given. Briner Meier (Ref 2) attempted to ozonize acet in a gaseous form, but instead of ptepg an acet ozonide, they obtd C02, HCOOH HCHO. Doevre (Ref 3) conducted ozonization of acet in solns. Schroeter (Ref 4) conducted ozonization of acet in the presence of org catalysts, particularly ether. No compns of resulting products were given... 

As it has been shown the main products of cumene ozonolysis are OZ, DMPC and CHP. In acetic acid, the product composition remains the same, but the amount of the products is decreased by about 1.6 times. The rates of CHP and OZ formation are lower by about 8.8 and 1.6 fold, respectively, and the rate of DMC accumulation grows 1.6 times. The ratio of the products is found to be 2.1 1.9 1 = OZ DMPC CHP. The rate constant (k) characterizing the ozone-acetic interaction at ambient temperature amounts to 1.5x10 M.s that is by about S.SxKH smaller than that found for the ozone reaction with cumene (k = 0.35 M. s ). It is known that AcOH deactivates ozone, inhibits R02 -radicals and protects the benzene ring [9-101], The deactivation of ozone in AcOH is also confirmed by the change of the molar coefficient in the UV-spectmm as compared with that in CCl,. 

Ozone acetic acid Ketocarboxylic acids by abnormal ozonolysis... 

Aniline Nitric acid, peroxides, oxidizing materials, acetic anhydride, chlorosulfonic acid, oleum, ozone... 

Nitric oxide Aluminum, BaO, boron, carbon disulflde, chromium, many chlorinated hydrocarbons, fluorine, hydrocarbons, ozone, phosphine, phosphorus, hydrazine, acetic anhydride, ammonia, chloroform, Fe, K, Mg, Mn, Na, sulfur... 

Diseleno acetals and ketals are cleaved more rapidly than their dithio counterparts a methyl derivative is cleaved more rapidly than a phenyl derivative. Methyl iodide or ozone converts diseleno acetals and ketals to vinyl selenides. ... 

Other reagents which oxidize acetals such as ozone and TV -bromosuccinimide show similar reactivitjrtrepds. ... 

The acid (3 g) is refluxed with excess acetic anhydride for 45 min, and the excess anhydride evaporated in vacuo. The residue is dissolved in 100 ml. of chloroform and cooled in a bath of ice and hydrochloric acid. With stirring, a solution of 1.45 g of bromine (1 mole) in 50 ml of chloroform is added during 1 hr. Ozonized oxygen is passed through the cold solution until no more ozone is absorbed. The solvent is evaporated in vacuo below 30° and... 

A stream of ozone is passed into a solution of 17j5-hydroxyestr-5(10)-ene-3-one acetate (123a, 4.2 g) in methylene dichloride (17 ml) and methanol (20 ml)... 

P-Hydroxy-A-norpregn-3(5)-en-2-one (7) A solution of the hydroxy-methylene steroid (5) (24.8 g) dissolved in 240 ml of acetic acid and 240 ml of ethyl acetate is ozonized at — 10° with one molar equivalent of ozone. The resulting solution is diluted with 240 ml. of water and 60 ml of 30 % hydrogen peroxide and allowed to stand overnight. The solution is diluted with 1.5 liters of water and extracted with 3 x 700 ml portions of ethyl acetate. The combined extracts are washed with water, saturated sodium chloride solution, dried over sodium sulfate and concentrated to dryness under vacuum, leaving 23.4 g of a colorless amorphous residue of crude diacid. This material shows a maximum in the ultraviolet spectrum at 224 mp (s 6,400) indicating a 53 % yield of unsaturated acid (6). It is used without further purification. 

Ozonization of A -steroids usually gives complex mixtures (however, see ref. 48). Ozonolysis became a practical step in the general synthesis of B-norsteroids with the discovery that added methanol" (or formaldehyde ) improves yields significantly. Thus, Tanabe and Morisawa prepared 5/ -hydroxy-6/ -formyl-B-norsteroids (74) from cholesterol acetate, dehydroepiandrosterone acetate and pregnenolone acetate in overall yields of 64-74% by the reaction sequence represented below. 

P-Formyl-B-nor-5 -cholestane-3, 5P-diol 3-Acetate (74). To an ozonized solution of 5 g of cholesterol acetate prepared as above is added 10 g of zinc dust followed by dropwise addition of 40 ml of acetic acid with stirring and... 

Ozone. Most acetals are subject to cleavage with ozone, giving a mono ester of the original diol. 

They have also carried out the oxidation of selinene by means of ozone and potassium permanganate and have thus been able to establish that the regenerated selinene is not absolutely identical with the natural selinene. They are the first to record the existence of a hemi-cyclic-sesquiterpene this compound is termed pseudo-()3)-selinene. By passing a current of ozone into a solution of natural selinene (pseudo-( 8)-selinene). in acetic acid, there is obtained a diketone, CjjHogOj, which is purified by treatment with permanganate in acetone solution. Its properties are as. follows —... 

Low -molecular-weight ozonides are explosive and are theretore not isolated. Instead, the ozonide is immediately treated with a reducing agent such as zinc metal in acetic acid to convert it to carbonyl compounds. The net result of the ozonolysis/reduction sequence is that the C=C bond is cleaved and oxygen becomes doubly bonded to each of the original alkene carbons. If an alkene with a letrasubstituted double bond is ozonized, two ketone fragments result if an alkene with a trisubstituted double bond is ozonized, one ketone and one aldehyde result and so on. 

Compound A, C10H 8O, undergoes reaction with dilute H2S04 at 50 °C to yield a mixture of two alkenes, QpH ir>. The major alkene product, B, gives only cyclopentanone after ozone treatment followed by reduction with zinc in acetic acid. Identify A and B, and write the reactions. 

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