Acetaldehyde Infrared Spectrum

Di-/x-chlorotetrakis(ethylene)dirhodium does not melt. The product is best characterized by elemental analysis and by its infrared spectrum (KBr wafer), which has medium to strong absorptions at 3060, 2980, 1520,1430, 1230,1215, 999, 952, 930, and 715 cm.-1. It is sparingly soluble in all liquids and cannot be purified by recrystallization. The compound is relatively stable to air at room temperature, but stored samples develop the odor of acetaldehyde and darken superficially. It is preferred to store [Rh2Cl2(C2H4)4] at around 0°. 

Acetaldehyde is converted into high polymer at 203 K in the presence of alumina as catalyst.C0O3 and M0O3 also give high polymers in much smaller yields. Polyacetaldehyde is a white, non-sticky and hi y elastic material, whose structure is shown to be methylpolyoxymethylene by the infrared spectrum. The cationic mechanism has been suggested for the polymerization. ... 

Both acetic acid and acetaldehyde have an absorption in the 3100 cm region of the infrared and are unlikely since no absorption in this region was observed. When the IR spectrum of honoopolymer PVC impregnated with acetyl chloride was measured, two absorptions in the carbonyl region are observed at 1776 and 1722 cm . These two absorptions correspond quite well with those of the degraded cc olymer. It does however indicate that the radical has abstracted a chlorine from the polymer, a process generally considered imlikely. 

From structure CXCIX, it might be expected that haemanthidine exists in equilibrium with the open chain and hemiacetal forms (CCII, R = H and CCIII, R = H, respectively). It would appear that only a very small amount of CCII (R = H) can be present at any one time, since the alkaloid shows no carbonyl band in the infrared and a normal methylenedioxyphenyl ultraviolet spectrum. Haemanthidine, spotted on paper, gives no secondary amine test with alkaline sodium nitro-prusside and acetaldehyde. However, it seems likely that, under certain... 

The barrier to internal rotation of the methyl group of acetaldehyde was initially determined by Kilb et al. from an analysis of the microwave spectrum. Since then, the values of the potential constants have been continually revised. Recently, Crighton and Bell combined the available microwave and infrared data with ab initio theory and refined the torsional parameters. Table 17 collects their internal rotation parameters. 

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