Acid anhydrides infrared spectra

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. 

Infrared radiation, electromagnetic spectrum and, 419, 422 energy of. 422 frequencies of, 422 wavelengths of, 422 Infrared spectroscopy, 422-431 acid anhydrides, 822-823 acid chlorides, 822-823 alcohols. 428, 632-633 aldehydes, 428. 730-731 alkanes, 426-427 alkenes, 427 alkynes, 427 amides. 822-823 amines, 428, 952 ammonium salts, 952-953 aromatic compound, 427-428, 534 bond stretching in, 422... 

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),... 

The simpler examples are readily hydrolysed in aqueous solution, and therefore react with sodium hydrogen carbonate and also give the ester test they may be confirmed by applying the hydroxamic ester test (Section 9.5.3, p. 1222). Carbonyl adsorption is apparent in the infrared spectrum at about 1820 cm-1 and at about 1760cm-1. It should be noted that aromatic anhydrides and higher aliphatic anhydrides are not readily hydrolysed with water and are therefore effectively neutral (Section 9.5.3, p. 1218). The final characterisation of the acid anhydride is achieved by conversion into a crystalline carboxylic acid derivative as for add halides. 

Treatment of A -acetylglycine (4) with benzaldehyde in the presence of sodium acetate and acetic anhydride gave compound A, C,H NOi, which did not possess OH or NH absorption in the infrared spectrum. When compound A was heated with water it gave acid B, C, H,N03. Identify compounds A and B. 

The acetolysis of S-acetyl-l,2-0-isopropylidene-3,5-di-0-methyl-6-thio-a-D-glucofiiranose with acetic acid—acetic anhydride—sulfuric acid gave a small yield of the crystalline septanose triacetate (271). The septanose structure of 271 was established by the absence of the thiol band in its infrared spectrum, and by the signals for three O-acetyl and two O-methyl groups found in its nuclear magnetic resonance spectrum. 

The Infrared spectrum of the SMA copolymer labeled SMA-2, is consistent with other SMA copolymer spectra published (33). However, the absorption peaks in the range of 1700 - 1820 cm indicate that this copolymer has been partially esterified to yield a half/acid ester of maleic anhydride which should exhibit peaks in the range of 1700 - 1725 cm"l and 1735 -1750 cm (Figure 3). The small absorption bands at 1780 and 1820 cm indicate the presence of a small amount of unreacted maleic anhydride. These data appear to be consistent for those of a styrene-maleic anhydride copolymer reported by Muskat (34). The carbon, hydrogen, oxygen analyses indicate that this polymer is a half/acid ester of a 90% styrene/10% maleic anhydride copolymer wherein theoretical values of C, H and 0 are 88.89%, 7.017. and 2.58% versus values of 89.14%, 7.68% and 2.81% found for C, H and 0, respectively. The solubility parameter was found to be equal to 9.47 H. 

Among the tropolone compounds found in nature are four tropolone-carboxylic acids,obtained from mold cultures.Two ofthese,stipitatonicadd(CXIV,R = COOH) and stipitatic acid (CXIV, R = H) have been obtained from Penicillium stipitatum (Bentley and Thiessen, 1963). Puberulonic add (CXV, R = COOH) and puberulic acid (CXV, R = H) were obtained from P. aurantio-virens, P. puberulum and P.johan-nioli as well as from strains of the P. cyclopium-viridicatum series (sources quoted in this paper). The infrared spectrum of the sodium salt of the anhydride of stipitatonic... 

To a 5-mL flask with a capillary inlet attached to a source of dry nitrogen, was added 4.72 g of the Diels-Alder cycloadduct from cyclooctatriene and dimethyl acetylenedicarboxylate. The flask was connected to a 25-cm tube, which served as an air-cooled condenser, and which led to a trap cooled with liquid nitrogen. The system was evacuated at 100 mmHg, and the flask was heated in a bath at 200° C for 20 min. The flask was cooled, and nitrogen was admitted. The trap contained 0.97 g cyclobutene (95%), which was solid at the temperature of liquid nitrogen and liquefied when placed in a dry ice bath at —78°C. The residue from the pyrolysis of cycloadduct was shown to be dimethyl phthalate by comparing its infrared spectrum with the spectrum of an authentic sample and by saponification to phthalic acid, isolated by sublimation as phthalic anhydride. 

Each structural assignment of signals 1-7 in the spectrum of Figure 4 is based on the addition of the authentic compound to the crude ozonolysis mixture, and—aside from peak 1—is also based on additional analytical evidence 2,2,3,3-tetrabromobutane (peak 2), 3,3-dibromobu-tanone (peak 4), and acetic acid were actually isolated while acetyl bromide (peak 3) as well as acetic anhydride (peak 5) were further identified by their sensitivity to solvolysis reactions, particularly hydrolysis and alcoholysis to form the corresponding esters. Diacetylperoxide (peak 6) was identified by the disappearance of peak 6 from the NMR spectrum as well as the disappearance of the typical infrared bands at 1810 and 1835 cm"1 when the reaction mixture was treated with sodium iodide. 

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