Cyclic trace formula

He and his students then tried to s oithesize simple analogs of the above monomeric unit, an endeavor which proved fruitless, but, in the course of their studies, they accumulated a large amount of knowledge regarding the preparation and properties of cyclic acetals. Thus, they found that a trace of acid catalyzes the formation of a polymer from 5,6-dihydroxy-2-hexanone, and that aliphatic aldehydes (RCHO) readily combine with chloral to give polymers of the general formula (2 RCHO -j- CUCCHO). ... 

Determine the structure for a compound with formula C3H5CIO. The IR spectrum, NMR, NMR, DEPT, COSY, and HETCOR (HSQC) spectra are included in this problem. The infrared spectrum has a trace of water that should be ignored (region from 3700 to 3400 cm ). The HETCOR spectrum should be carefully examined, for it provides very important information. You will find it helpful to consult Appendix 5 (alkanes and cyclic alkanes) for values of coupling constants. Determine the coupling constants from the NMR spectrum, except for proton c, and compare the calculated values to those shown in Appendix 5. Draw the structure of the compound, and label the protons on the structure. 

The same synthetic approach was used for the preparation of cyclic anhydrides [39- 3]. It was known before that succinic and glutaric acid form cyclic anhydrides which do not polymerize (see Formula 3.1, bottom). HiU and Carothers studied the reactions of higher dicarboxylic acids with acetyl chloride or acetic anhydride. In aU cases, polymeric anhydrides were obtained which were supposed to possess mixed anhydride end groups containing acetyl residues. The sensitivity to hydrolysis alcoholysis and phenolysis prevented exact molar mass measurements. However, a reliable distinction from monomeric cyclic anhydrides was achieved by reaction with aniline, because cyclic anhydrides can only yield one reaction product. When the polymeric anhydrides were heated to 150 °C in vacuum they degraded almost completely by back-biting . In this way 10 new cyclic anhydrides were isolated. These cyclic anhydrides underwent rapid polymerization in contact with traces of moisture. 

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