Rate enhancement of organic reactions by microwaves at atmospheric pressure
Article Abstract:
Small rate enhancements are achieved for some reactions of organic chemicals at atmospheric pressure with microwave reflux in a modified domestic microwave oven. The rate of the Knoevenagle reaction of acetophenone with ethyl cyanoacetate is enhanced by a factor of 2.5, but in a variable-frequency microwave oven there was no rate increase vs conventional heating to the same temperature. Probably hot spots or superheating of solvent caused the small rate enhancements seen. Likely nonthermal effects were not responsible.
Publication Name: Canadian Journal of Chemistry
Subject: Chemistry
ISSN: 0008-4042
Year: 1998
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Synthesis of the first (n)paracyclophane with an annulene as the aromatic, a necklace-like molecule; NMR, X-ray, and MMX structural comparisons
Article Abstract:
The (18)paracyclo(14)annulene has been prepared from 1,14-tetradecanedioyl dichloride and 2,7-bis(hydroxymethyl)-10b,10c-dimethyldihydropyrene. This is the first synthesis of (n)paracyclophane with an annulene as the aromatic. Structural comparisons have been made based on NMR, X-ray, and MMX analysis. The molecule of the product is shaped like a necklace and has protons H(9/6), but not those at the center of the necklace chain. The pendant is the dihydropyrene ring. It can freely spin at room temperature in solution.
Publication Name: Canadian Journal of Chemistry
Subject: Chemistry
ISSN: 0008-4042
Year: 1998
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1,2-bis(1-aryl-3-alkytriazen-3-yl)ethanes and related compounds
Article Abstract:
The characteristics of several bistriazenes are described. Known as 1,2-bis(1-aryl-3-alkyltriazen-3-yl)ethanes, they are stable crystalline structures synthesized by diazonium coupling with N,N'-dimethylethylenediamine. Three confirmations are noted, namely anti-anti, syn-syn, and syn-anti. Electron-withdrawing groups on the aryl ring restrict rotation around the N2-N3 bond of the triazene units.
Publication Name: Canadian Journal of Chemistry
Subject: Chemistry
ISSN: 0008-4042
Year: 1998
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