Anhydrides, infrared spectra

Succinic anhydride (35, Z — O) can theoretically tautomerize to 36, but all the evidence indicates that it exists overwhelmingly as 35 for example, the infrared spectrum shows v C=0 bands. ... 

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. 

Repeated methylation of bagasse native lignin with dimethyl sulfate yielded a product with a 29-1 % methoxyl content. Four such methyl-ations did not change this value. However, the infrared spectrum of this derivative still revealed a small absorption band at 3400 cm1. Thus, it appeared that at least one hydroxyl group could not be methylated. Treatment of this methylated product with acetic anhydride and pyridine gave an acetate, which did not exhibit an absorption band at 3400 cm-1. Consequently, a tertiary hydroxyl group, which can be acetylated but not methylated, seems to be present in this lignin. 

The initial observation is that PMMA is essentially completely degraded to monomer by heating to 375°C in a sealed tube while heating a mixture of red phosphorus and PMMA under identical conditions yields a solid, non-deqraded, product as well as a lower yield of monomer. One may observe, by 3C NMR spectroscopy, that the methoxy resonance is greatly decreased in intensity and methyl, methoxy phosphonium ions are observed by 31P NMR. Additional carbonyl resonances are also seen in the carbon spectrum, this correlates with a new carbonyl vibration near 1800 cm 1 in the infrared spectrum and may be assigned to the formation of anhydride. The formation of anhydride was also confirmed by assignment of mass spectra obtained by laser desorption Fourier transform mass spectroscopy, LD-FT-MS. 

Figure 11.4 The micro-infrared spectrum of gel shown in Fig. 11.3. The spectrum suggests it is an oxidized PE gel containing maleic anhydride.

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 formation of block copolymers from styrene-maleic anhydride and acrylic monomers was also indicated by pyrolytic gas chromatography and infrared spectroscopy. A comparison of the pyrograms of the block copolymers in Figure 7 shows peaks comparable with those obtained when mixtures of the acrylate polymers and poly(styrene-co-maleic anhydride) were pyrolyzed. A characteristic infrared spectrum was observed for the product obtained when macroradicals were added to a solution of methyl methacrylate in benzene. The characteristic bands for methyl methacrylate (MM) are noted on this spectogram in Figure 8. 

Fig. 3.34 Infrared spectrum of acetic anhydride recorded as a liquid film.

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. 

If the unknown, neutral, oxygen-containing compound does not give the class reactions for aldehydes, ketones, esters and anhydrides, it is probably either an alcohol or an ether. Alcohols are readily identified by the intense characteristic hydroxyl adsorption which occurs as a broad band in the infrared spectrum at 3600-3300 cm-1 (O—H str.). In the nuclear magnetic resonance spectrum, the adsorption by the proton in the hydroxyl group gives rise to a broad peak the chemical shift of which is rather variable the peak disappears on deuteration. 

There is the 3 methods for preparing of 8-azaspiro(4.5)decane-7,9-dione, 8-(4-(4-(2-pyrimidinyl)-l-piperazinyl)butyl) monohydrochloride (U.S. Patent 3,717,634). One of them is follows a mixture of 0.1 mole of the substituted glutaric anhydride, 0.1 mole of l-(4-aminobutyl)-4-(2-pyrimidinyl)piperazine (U.S. Pat. 3,398151), and 300 ml of pyridine was refluxed until imide formation was completed. The degree of reaction was readily followed by taking an aliquot portion of the reaction mixture, removing the solvent, and obtaining the infrared absorption spectrum of the residue. When reaction is complete, the spectrum exhibited typical infrared imide bands at 1701 and 1710 cm-1 whereas if incomplete, the infrared spectrum contains amide and carboxyl absorption bands at 1680, 1760 and 3300 cm 1. 

Infrared spectrum of propionic anhydride, showing C = 0 stretching absorptions at 1818 and 1751 cm-1. 

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. 

Bis(maleic anhydride)nickel(O), an orange air-sensitive compound, soluble in acetone but not in benzene, is obtained by reaction of maleic anhydride with Ni(CO)4 (600). With Ni(CO)4, diphenylcyclopropenone yields, in addition to diphenylacetylene and tetraphenylcyclopenta-dienone, a pale green diamagnetic complex [(CaH5)2C2CO]gNi(CO), melting at 188°C, which is presumably tris(Tr-diphenylcyclopropenone)-carbonylnickel (66). The infrared spectrum of the complex indicates coordination at the double bond. 

The infrared spectrum of neat acetic formic anhydride... 

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. 

Spectrographic characterization. The infrared spectrum of the mixed anhydride shows bands in the carbonyl region at 1765 and 1791 cm-1 and carbon-oxygen-carbon stretching absorption at 1050 cm 1 (a band at 1180 cm-1 could also be due to C—O—C). The NMR spectrum shows singlets at S = 2.25 (acetyl protons), and at S = 9.05 (formyl proton). 

Then 500 ml. of distilled water is added and the mixture boiled for 1-2 hours to destroy excess acetic anhydride and peroxides and to remove most of the methylene chloride. The solid which separates is collected after cooling and dissolved in the combined ethereal extracts (3 x 100 ml.) from the supernatant aqueous phase. The etheral solution is washed with 5% sodium carbonate solution, water, and brine, and dried over anhydrous sodium sulfate. Evaporation of the solvent yielded 87-96 g. (80-88.5%) of crude lactone, m.p. 87-89.5°. Two crystallizations from 95% ethanol afforded 78.5-86.2 g. (73.5-80%) of fine white crystals, m.p. 93.0-94.0°. The infrared spectrum exhibited peaks at 5.78 /a (0=0), 7.65 fi and 8.60 (C—O—C). The NMR spectrum (CD,), SO (TMS internal standard at 100 MHz) showed a characteristic aromatic multiplet at 5.4-6.6 (8 H). 

The infrared spectrum of matrix-isolated 3,4-didehydropyridine 2 has been reported. This is the first direct observation of a heteroaryne. 3,4-Pyridinedicarboxylic anhydride 714 was deposited in an Ar or N2 matrix and irradiated at 13 K with light > 340 nm 714 gave CO, CO2 and peaks assigned to 2, whereas subsequent irradiation with higher-energy light... 

FIGURE 2.57 The infrared spectrum of propionic anhydride (neat liquid, KBr plates). 

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