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Ring closure reactions O 0130Solvent-Free Friedel-Crafts Cyclization with Trichloroacetic Anhydride. -The scope of the title reaction is explored with the synthesis of tetralones (II), benzothiopyrans (IV), benzoxepins and benzothiepines (VIII) as well as dibenzoxepins and dibenzothiepins (VI). Phenoxy-or phenylthiopropanoic acids do not react to the corresponding benzofuran or benzothiophene derivatives and the formation of eight-membered heterocycles such as (VIIIc) also fails. -(ANDREWS, B.; BULLOCK, K.; CONDON, S.; CORONA, J.; DAVIS*, R.; GRIMES, J.; HAZELWOOD, A.; TABET, E.; Synth. Commun. 39 (2009) 15, 2664-2673; Chem. Dev., GlaxoSmithKline, Research Triangle Park, NC 27709, USA; Eng.) -H. Haber 51-039
Fabrics padded with either N,N'-dimethyloldihydroxyethyleneurea (DMDHEU), 4,5-dihydroxyethyleneurea (DHEU), or N,N'-dimethylethyleneurea (DMeEU) were subjected to drying and curing conditions over a range of temperatures from ambient to 160°C. A portion of each fabric remained unwashed and a portion was given a neutral wash with a nonionic detergent. In all cases, 13C-NMR spectra of neutral extracts at 40°C or 80°C of the fabrics treated with DHEU or its derivatives revealed the presence of the reactants and, in the case of DMDHEU, formaldehyde, in ap proximately millimolar concentrations. The extracts of washed fabrics that had been treated with DMeEU contained no chemicals. The results confirm that the crosslinking reactions and the methylolation reactions are reversible, and indicate that permanent sorption of these chemicals on the cotton without reaction is unlikely. All DMDHEU treated fabrics released small amounts of formaldehyde when exposed to moisture and elevated temperature.
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