Acetic acid infrared spectra

Although no chemical reaction occurs, measurements of the freezing point and infra-red spectra show that nitric acid forms i i molecular complexes with acetic acid , ether and dioxan. In contrast, the infrared spectrum of nitric acid in chloroform and carbon tetrachloride - is very similar to that of nitric acid vapour, showing that in these cases a close association with the solvent does not occur. 

Treatment of 2 4 6 tn tert butylphenol with bromine in cold acetic acid gives the compound CigH29BrO in quantitative yield The infrared spectrum of this compound contains absorptions at 1630 and 1655 cm Its H NMR spectrum shows only three peaks (all singlets) at 8 1 2 13 and 6 9 in the ratio 9 18 2 What is a reasonable structure for the compound" ... 

Compound A undergoes hydrolysis of its acetal function in dilute sulfuric acid to yield 1,2-ethanediol and compound B (CgHg02), mp 54°C. Compound B exhibits a carbonyl stretching band in the infrared at 1690 cm and has two singlets in its H NMR spectrum, at 8 2.9 and 6.7, in the ratio 2 1. On standing in water or ethanol, compound B is converted cleanly to an isomeric substance, compound C, mp 172—173°C. Compound C has no peaks attributable to carbonyl groups in its infrared spectrum. Identify compounds B and C. 

N-Acetylation of Kasugamycinic Acid (9a). A solution of kasugamycinic acid (225 mg.) dissolved in 10 ml. of water was treated with acetic anhydride (0.3 ml.) under cooling sodium bicarbonate was used to keep the pH 7.2 and stirring continued for 30 minutes. The reaction product was passed through Dowex 50W-X2 (H form) and the column was washed with water. The combined filtrate was subjected to lyophilization to afford 234 mg. of a crude N-acetyl derivative. Its infrared spectrum showed strong absorptions at 1740 cm-1 characteristic of oxamic acid group. The N-acetyl derivative (178 mg.) was treated with 40 ml. 

The trapped product gave an immediate test with KI in acetic acid. Its infrared spectrum was similar to that of 3-butene-2-ol with major absorption peaks at 3, 8.7, 9.5, 10.3, and 10.8 microns and minor peaks at 6.3, 7.2, 7.7, 11.6, 12.4, and 12.6 microns. There was no absorption arising from carbonyl. In a 25% solution of hydroperoxide in carbon tetrachloride, the hydroperoxide proton gave rise to a broad band at 8.7 p.p.m. (referred to TMS) in the NMR spectra. 

Tetrakis(acetato)di- U-amido-diborane is a white crystalline compound which is not too sensitive to moisture. It can be stored in a nitrogen atmosphere in a refrigerator for long periods without decomposition. It is sparingly soluble in most organic solvents and slowly dissolves in glacial acetic acid and acetic anhydride. Monoclinic and triclinic crystalline forms were obtained by recrystallization from acetic anhydride and glacial acetic acid, respectively.1 The infrared spectrum recorded (Beckman i.r.-12) by the KBr pellet technique contains major absorption bands (at frequencies cm.-1) 3280(s), 3230(s), 3100(s), 1740(w,sh),... 

Fig. 38.—The shift with temperature of the infrared absorption spectrum of the carbonyl group in acetic acid.

The manner in which these dimers break up into monomers offers an interesting problem in kinetics which can be studied by means of the infrared absorption spectrum. Acetic acid vapor at 19 mm. was examined13 from 1 jx to 10/x in an eight centimeter cell at 25° and at 172°. Several bands appear in this region and five fundamental frequencies were found corresponding to five fundamental modes of vibration. 

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