Mechanistic Investigation of the Reactions between Cyclohexane Carboxaldehyde and Ureido Groups

Model reactions have been performed to explore the reactivity of a variety of ureido groups with cyclohexane carboxaldehyde. The reaction mechanism between ureido and aldehyde functionalities is more complicated than expected. A new heterocyclic product was identified, which is very stable and solvent resistant. The final product profile is reactant and solvent dependent. In the cases of urea, alkyl urea, and benzyl urea, the reaction pathway goes from hemiaminal to aminal, to enamine, and finally to the heterocyclic product with nearly 100% yield. For other investigated ureido groups, the reaction stopped at the enamine product, and products are a mixture of hemiaminal, aminal, and enamine. All reaction steps are reversible except for the last step. The structure of the unique cyclic product was determined combining NMR and LC–MS analysis, and the reaction pathway was verified by kinetics studies

Terminal and Internal Unsaturations in Poly(ethylene-<i>co</i>-1-octene)

Unsaturated structures in polyolefin polymers are important in many respects. In this work, new vinyl and vinylidene structures were identified in poly­(ethylene-<i>co</i>-1-octene) copolymers. The combination of careful sample selection and model compounds provided clear evidence for the assignment of these structures. More importantly, a new method was developed to differentiate and quantify for the first time terminal and internal unsaturations in ethylene-<i>co</i>-1-octene copolymers. The method described here will be generally applicable to many different polyolefins

Isoclast Active Manufacture: In Situ Spectroscopic Investigation of the Unstable Products of Cyanamide and Sodium Hypochlorite Reactions

Isoclast Active is a new insecticide manufactured by Dow AgroSciences LLC. In an effort to lower the cost of manufacture of Isoclast Active, we have studied the reaction which produces <i>N</i>-cyano sulfilimine, which is the precursor to Isoclast Active. The reaction involves the oxidative coupling of cyanamide with the sulfide intermediate using sodium hypochlorite. In this study, we demonstrated that a transient intermediate species is produced by the reaction between bleach and cyanamide. On the basis of in situ Raman, IR, and NMR spectroscopic evidence we propose that the intermediate is the anionic form of <i>N</i>-chlorocyanamide: ClN^––CN. The degradation of this intermediate species was found to be highly sensitive to its environment and leads to a complicated mixture of products. This work also demonstrates that in situ Raman and IR spectroscopy are powerful and invaluable tools for monitoring reactions/processes involving unstable reaction intermediates for kinetic modeling and process R&D