The Initial Attack of Ozone on Unsaturated Systems. Ozonolyses of Unsymmetrical Derivatives of 1,2-Dibenzoylethylene¹

Abstract

VOl. s2The tan solution was examined by visible-ultraviolet spectroscopy and shown to contain 0.99 mmole of tricyanovinyl alcohol ( A, , , 297 mp, B 11,300) and 0.01 mmole of 1,1,2,3,3-pentacyanopropene (Amsx 397 and 414 mp, e 22,600 and 22,-100, respectively).When a solution of 0.81 g. (5.9 mmoles) of tricyanovinyl chloride in 4 ml. of tetrahydrofuran was treated with 2 ml. of water, a rapid (45 seconds) exothermic reaction took place with evolution of carbon dioxide (identified by the white precipitate it gave with lime water). The addition of 1 .O g. of tetramethylammonium chloride in 15 ml. of water followed by the removal of the tetrahydrofuran under vacuum gave 0.364 g. (51 %) of tetramethylammonium pentacyanopropenide, m.p. 310-312'.The ultraviolet-visible spectrum was identical with that of an authentic sample. Reaction ofTricyanovinyl Chloride with Tricyanovinyl Alcohol.-A mixture of 1.37 g. (0.01 mole) of tricyanovinyl chloride, 1.92 g . (0.01 mole) of the tetramethylammonium tricyanoethenolate and 15 ml. of tetrahydrofuran was heated under reflux on a steam-bath for 4 hours. The solid that separated weighed 2.33 g. It was shown to contain 0.0068 mole of pentacyanopropenide anion by spectroscopic examination. The filtrate yielded 0.45 g. (3370) of unreacted tricyanovinyl chloride after concentration and sublimation, Reaction of Tricyanovinyl Ethyl Ether with N ,N-Db methylanilme.-A solution of 1.47 g. (0.01 mole) of tricyanovinyl ethyl ether in 5 ml. of N,N-dimethylaniline was heated in a boiling water-bath for 30 minutes. The resultant deep red solution was taken up in 30 ml. of methylene chloride and extracted successively with two 25-ml. portions of cold 2 N hydrochloric acid, 25 ml. of water and 10 ml. of saturated sodium chloride solution. The organic layer was then concentrated and chromatographed on acid alumina (Woelm) using ethyl acetate-acetone for elution. The deep-red gummy solid weighed 0.95 g. and contained 0.74 g. (34% yield) of N,N-dimethyl-p-tricyanovinylaniline as shown by the visible absorption intensity a t 515 mp. The infrared spectrum of this gum indicated the absence of N,N-dimethyl-~-(2,2-dicyano-l-ethoxyvinyl)-aniline ,l*The study of the specificity of ozone attack on unsymmetrical olefins is continued with cis-1,2-dibenzoylpropene, cis-l,2-dibenzoyl-1-methoxyetliylene, cis-l-amino-1,2-dibenzoylethylene and cis-and trans-1,2-dibenzoylstyrene. The results of this study and of studies made elsewhere make it clear that there is no single type of initial ozone attack, nor is there a single route to peroxidic and non-peroxidic ozonation products after the inital ozone attack. With most olefinic double bonds, however, it appears that a five-membered ring intermediate is produced via, a t least in protolytic solvents, a rr-complex involving the terminal electrophilic atom of the ozoiie molecule.

Detection of double bond-ozone stoichiometry by an iodimetric method during ozonation processes

“…According to the resonance hybrid structure of ozone, it can behave either as an electrophilic or nucleophilic reagent in its initial attack [21]. There is a greater possibility of electrophilic attack than nucleophilic attack in the ozonolysis of carbon-carbon unsaturated bonds; however, electrophilic attacks are more common toward carbon-nitrogen double bonds [22,23]. Despite the mechanism, a stoichiomet- ric relationship must exist between ozone and the double bond.…”

Quantitative investigation of the ozonolysis reaction. XIV. A simple carbonium ion stabilization approach to the ozone cleavage of unsymmetrical olefins

“…Bailey's determinations (19) of the direction of cleavage of 1-substituted 1,2-dibenzoylethylenes, made by isolation of the ozonolysis products in the presence of methanol, have indicated that the inductive, rather than the resonance effects, play a role in distributing the proportions of cleavage. Similarly, Keaveney et al (20) have measured the proportions of cleavage of styrene, propenylbenzene, and 2-methyl-propenylbenzene by isolation of the reaction products.…”

Functionalized Imides by Regioselective Ozonation

“…In a sequence of concerted 1,3-dipolar cycloaddition and cycloreversion, carbonyl oxides [4] are formed which are captured by internally generated carbonyl compounds in another 1,3-dipolar cycloaddition to yield ozonides. As a result, for unsymmetrical alkenes, substituent rules for the regioselective OÀO splitting in the cycloreversion step have been formulated [5] [6]. There are, however, exceptions from these rules, and the ozonide-forming step may be bypassed due to low dipolarophilicity of the carbonyl intermediate.…”