Acetyl chloride infrared spectrum

Attempted Reaction of K[Cr(HO-A)2] with Acetyl Chloride. One gram of K[Cr(HO-A)2] and 50 ml. of acetyl chloride were placed in a flask and refluxed for 24 hours. At the end of this time K[Cr(HO-A)2] was recovered unchanged (infrared spectrum) the liquid phase was colorless, indicating insolubility of the complex. 

Attempted Reaction of (Me4N) [Cr(HO-A2] with Acetyl Chloride in Acetonitrile. In 200 ml. of acetonitrile were placed 0.50 gram (0.00105 mole) of (Me4N) [Cr(HO-A)2], 1 ml. of pyridine, and 18 drops (excess) of acetyl chloride. The solution was warmed and within a few minutes the color changed from red to green. On evaporation a green oil was obtained, the infrared spectrum of which gave no indication of the presence of ester. 

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. 

On the other hand, the palladium and platinum complexes of pyridine-2-aldoxime, when treated with acetyl chloride in hot chloroform, gave stable chelates containing the acylated ligand. A monoacetylated palladium chelate was isolated in which 1 mole of pyridine-2-aldoxime was replaced by two chloride ions (see reaction XXIV). This compound was identified by its infrared spectrum, which had a strong carbonyl absorption band near 1790 cm-1. The platinum complex of pyridine-2-aldoxime gave a... 

FIGURE 2.55 The infrared spectrum of acetyl chloride (neat liquid, KBr plates). 

Acyl chlorides have C=0 stretching absorptions at higher wavenumber (1800 cm ) than esters, and amides have C=0 stretching absorptions at lower wavenumber (1650—1655 cm ). These different values reflect the contribution of inductive and resonance effects in the stabilization of the Lewis structure of a carbonyl group compared to the dipolar resonance form. The chlorine atom of acyl chlorides inductively withdraws electrons from the carbonyl carbon and destabilizes the dipolar resonance form, thus leading to an increase in the double bond character of the carbonyl group. Figure 21.5 shows the infrared spectrum of acetyl chloride. 

The solvents and coupling reagents were reagent grade materials. The tricaprylmethylammonium chloride (Adogen 464) was not purified further. Intrinsic viscosities were measured in chloroform at 25. Infrared spectra for hydroxyl analysis were measured on 2.5% solutions in carbon disulfide (vs. carbon disulfide2.in a cell with a 1.00 cm path length. The absorbance at 3610 cm was subtracted from a similar spectrum of 2 which had been quantitatively acetylated. 

The uniquely distinguished axial alcohol at C5 was activated by triflation and the resultant triflate was displaced by the action of tetra n-butylammonium azide in benzene at room temperature. Compound 25 was thus available in 86% yield from alcohol 24. Hydrogenolysis ((H24 d(OH)2C) followed by acetylation afforded compound 26 in 96% yield. TTie richly detailed NMR spectrum (490 MHz) of 26 was identical in every respect with that of the L-antipode derived from reaction of NeuSAc, first with acidic methanol and then with benzoyl chloride under the influence of DMAP. The infrared and mass spectra, as well as the chromatographic characteristics of the two materials, were identical. 

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