I I
GUEST AUTHOR
D. G. M. Diaper Royal Military College of Canada Kingston, Ontario
Textbook Errors, 76
~zonoIysis
Although it is hard to pinpoint errors of fact in textbook discussions1 of ozonolysis of olefins, incorrect emphasis in presentation of the reaction has caused misconceptions about its scope and utility. This is particularly regrettable because the beginning student meets alkene ozonolysis at an early stage, when he is impressionable and easily confused. A 1,2,3-trioxolane (11) is the product logically expected from an olefin (I).
I1
111
The reaction would then conform with other olefin addition reactions in which the a system is opened leaving the r bond between the carbon atoms intact. It is now believed that the first step in an ozonolysis is a 1,3dipolar addition analogous to other cyclo-addition reactions (1). The term "molozonide" has been used for both I1 and 111, a modernized representation of the originally proposed structure for the primary ozonization product. Until recently, no examples of either structure had ever been unequivocally identified, and the main evidence for the constitution of the primary product was low temperature experiments on ozonization followed by reduction using certain trans-1,Pdisubstituted ethylenes (2, 3 ) . Production of diols from these primary ozonides confirmed the existence of the central C-C bond but did not distinguish between structures I1 and 111. Recent NMR studies (4) on the primary low-temperature product from trans-1,2-di-tbutylethylene now support structure I1 in this case because the methine proton signal, a singlet, showed that the two methine protons have identical environments. It is curious that the ozonization products from cis-1,B disubstituted ethylenes apparently do not give diols on reduction. Suggestions of material suitable for this column and guest columns suitable for publication directly should be sent with as many details RS po&ible, and partic~harly with references to modern textbooks, to W. H. Eherhsrdt, School of Chemistry, Georgia Institute of Technolow. . .. . Ablanta. Georeia ,. 30332. ' S n w the purptw
