2‐Methylene‐1,3‐dioxepane 6 polymerized with a quantitative ring opening to form poly‐ϵ‐caprolactone via a free radical mechanism. On the other hand, 2‐methylene‐1,3‐dioxolane (ethylene ketene acetal) 4 and 2‐methylene‐1,3‐dioxane 5, under the same conditions, generated polymers with mixed ring‐opened and nonring‐opened structures. In copolymerization monomer 6 also showed a high tendency toward ring opening by which the ester functionality could be conveniently introduced into the backbone of the addition polymers.

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The cyclic ketene acetal, 2-methylene-4-phenyl-1,3-dioxolane (3), was shown to undergo free radical ring-opening polymerization to produce the polyester, poly[y-(8-phenyl)butyrolactone].The monomer 3 was synthesized by an acetal exchange reaction of chloroacetaldehyde dimethyl acetal with styrene glycol in an 87% yield followed by dehydrochlorination of the resulting cisand trans-2-chloromethyl-4-phenyl-1,3-dioxolane (2) with potassium tert-butoxide in tert-butyl alcohol in a 70% yield. 3 was shown to undergo essentially quantitative free radical ring-opening at all temperatures from 60 -150 "C and also nearly complete regioselective ring-opening with cleavage to give the more highly stable secondary benzyl free radical. Even in free radical copolymerization with styrene, methyl methacrylate, vinyl acetate, or 4-vinylpyridine, 3 gives essentially complete ring opening to introduce an ester groups into the backbone of the addition copolymer. The structures of the polymers were established by elemental analysis and 'H and l3C NMR spectroscopy.

Data from a statewide survey, conducted by the Indiana Prevention Resource Center, of 20,629 Indiana students in grades 5-12 were analyzed to determine the extent to which cigarette smoking predicted use of alcohol and other drugs and acted as a so-called "gateway drug." A three-stage purposive/quota cluster sampling strategy yielded a representative sample of Indiana students, stratified by grade. Cross-tabulated data revealed a strong, dose-dependent relationship between smoking behavior and binge drinking, as well as use of alcohol and illicit drugs. Daily pack-a-day smokers were three times more likely to drink alcohol, seven times more likely to use smokeless tobacco, and 10-30 times more likely to use illicit drugs than nonsmokers. A stepwise multiple regression analyzed the role that the student's perceptions of the risk of using drugs and of peer approval/disapproval of the student's drug use, gender, grade in school, and ethnic background played in predicting alcohol and other drug use.

Although unstrained five-or six-membered carbocyclic systems undergo free radical ring-closing polymerization, the introduction of an oxygen into the ring will promote free radical ring-opening polymerization, since the resulting carbon-oxygen double bond is approximately 50 kcal more stable than a carbon-carbon double bond. Thus, cyclic ketene acetals, cyclic ketene aminals, cyclic vinyl ethers, unsaturated spiro ortho carbonates, and unsaturated spiro ortho esters will all undergo free radical ring-opening polymerization. Copolymerization of these monomers with a wide variety of vinyl monomers will introduce an ester, amide, keto or carbonate group into the backbone of an addition polymer and can make possible the synthesis of functionally terminated oligomers, biodegradable addition polymers, thermally stable polymers, and monomers that expand on polymerization. KEY WORDS Free Radical Ring-Opening Polymerization I 2-Methylene-1 ,3-dioxepane 1 Polyesters I Functionally-terminated Oligomers I Unsaturated Spiro a-Carbonates I '\N+

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To investigate further the possible role of occupational exposures on mortality, an update of a large Texas petroleum refinery cohort was undertaken. Between 1937 and 1987, 6799 deaths were identified among 17,844 employees. Relative to the general population of Texas, the overall standardized mortality ratio (SMR) showed a statistically significant deficit, as did nine other cause-of-death categories. Statistically significant mortality excesses were found for bone cancer (SMR = 207.8: 95% confidence interval [CI], 110.6 to 355.3), acute lymphocytic leukemia (ALL) (SMR = 259.6; 95% CI, 112.1 to 511.5), and benign/unspecified neoplasms (SMR = 194.9; 95% CI, 129.5 to 281.7). However, none of these diseases demonstrated an exposure-response relationship with length of employment. Subcohort mortality analyses by sex and race groups, length of employment, interval since hire, period of hire, and pay status were also performed. Overall, the update findings do not indicate that any excess mortality occurred as a result of employment at the refinery.