Aqueous, infrared spectra

After concentrating the filtrate to approximately 400 ml, solids started crystallizing out at which time the filtrate was cooled by refrigerating at 5°C for several hours. Filtration gave 1B.7 g of L-Dopa, MP 284° to 286°C (dec.) [oJd 8.81° (1% solution in aqueous 4% HCI). The infrared spectrum and paper chromatography indicated very good L-Dopa according to U.S. Patent 3,253,023. 

After washing the combined extracts with ammonium chloride solution and water and working up in the usual way a white solid (IV) is obtained which after one recrystalli2ation from aqueous methanol has MP 242° to 243°C. The infrared spectrum of this compound indi-... 

Aero Hydrolysis. A solution of kasugamycin hydrochloride (1.5 grams, 3.46 mmoles) dissolved in 15 ml. of 6N hydrochloric acid was heated at 105°C. for five hours in a sealed tube. The solution was condensed to 5 ml. under a reduced pressure and the addition of 50 ml. of ethyl alcohol afforded a crude solid overnight. It was recrystallized from aqueous ethyl alcohol, showing m.p. 246°-247°C. (dec.). It showed no depression in the mixed-melting point and completely identical infrared spectrum with d-inositol which was supplied by L. Anderson of the University of Wisconsin. The yield was 81% (503 mg., 2.79 mmoles). Anal Calcd. for CgH12Og C, 40.00 H, 6.71 O, 53.29 mol. wt., 180.16. Found C, 40.11 H, 6.67 O, 53.33 mol. wt., 180 (vapor pressure osmometer). 

Procedure To the sample which contains 20-300 /xg of pertechnetate in 5-20 ml of solution, are added potassium perchlorate solution (2 ml, 1 mg KCIO per ml) and enough NaCl to make the solution approximately 1 M. The solution is heated and neutralized with ammonia. Pertechnetate is precipitated with aqueous 5 % tetraphenylarsonium chloride reagent. The precipitate is filtered, washed and dried, and a 2-mg portion is mixed with potassium bromide (300 mg). The mixture is pressed to form a clear disc by the usual technique. The infrared spectrum is recorded between 10 and 12 /x. The peak absorption is measured at 11.09 /X by the base-line technique. 

B. Hydrogenolysis of the Phenolic Ether Biphenyl. To a solution of 10 g. (0.032 mole) of the product from Part A in 200 ml. of benzene is added 2 g. of 5% palladium-on-charcoal, and the mixture is shaken with hydrogen in a Parr apparatus at 40 p.s.i. and 35-40° for 8 hours (Note 3). The mixture is filtered, and the insoluble residue is washed with three 100-ml. portions of hot ethanol (Note 4). The filtrates are combined, and the solvent is removed by means of a rotary evaporator at 60° (12 mm.) to leave a solid residue. The product is dissolved in 100 ml. of benzene, and 100 ml. of 10% sodium hydroxide solution is added. The mixture is shaken, and the layers are separated. The aqueous layer is extracted with 100 ml. of benzene, and the original benzene layer is washed with 100 ml. of water (Note 5). The benzene solutions are combined and dried over magnesium sulfate. Removal of the benzene by distillation yields 4.0-4.7 g. (82-96%) of biphenyl as a white powder, m.p. 68-70° (Note 6). The infrared spectrum is identical with that of an authentic sample, and a purity of at least 99.5% was indicated by gas chromatography analysis. 

The infrared spectrum of caprolactam has been given (3). Melting point data for the caprolactam—water system, as shown in Figure 1, are indicative of successful purification of caprolactam by crystallization from aqueous solution such purification is very effective for separating and rejecting polar impurities. 

The intense absorption of water over most of the infrared spectrum restricts the regions where aqueous solutions of carbohydrates can be usefully studied. Absorbance subtraction makes it possible to eliminate water absorbance and magnify the remaining spectral features to the limit of the signal-to-noise ratio. Many other data-processing techniques, such as the ratio method,4 the least-squares refinement,5 and factor analysis,6 should be of benefit in the study of carbohydrate mixtures. 

The infrared spectrum of the liquid mixture shows a broad absorption band at 3000-2700 cm-1 and an intense absorption band at 1613 cm 1. In cyclohexane solution, the substance has Amax at 272 nm with emax = 12,000. (a) What can you conclude from this data as to the magnitude of K, the equilibrium constant for the interconversion of the two forms (b) What can you deduce from the fact that the absorption at 272 nm is much weaker in aqueous solution (pH 7) than it is in cyclohexane ... 

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. 

B-13. An unknown compound, C9H10O2, did not dissolve in aqueous NaOH. The infrared spectrum exhibited strong absorption at 1730 cm-1. The H NMR spectrum had signals at S 7.2 ppm (multiplet), 4.1 ppm (quartet), and 1.3 ppm (triplet). Which of the following is most likely the unknown ... 

A substance is soluble in dilute aqueous HC1 and has a single peak in the region 3200-3500 cm-1 in its infrared spectrum. Which of the following best fits the data ... 

The mid-infrared spectrum of the cesium aluminosilicate unequivocally identified it as pollucite. Moreover, the SAM results indicate that the material is uncontaminated by foreign alkali metal ions, such as K+ or Na+ from the feldspars, or the aqueous media. 

Quantitative determinations of the thicknesses of a multiple - layered sample (for example, two polymer layers in intimate contact) by ATR spectroscopy has been shown to be possible. The attenuation effect on the evanescent wave by the layer in contact with the IRE surface must be taken into account (112). Extension of this idea of a step-type concentration profile for an adsorbed surfactant layer on an IRE surface was made (113). and equations relating the Gibbs surface excess to the absorbance in the infrared spectrum of a sufficiently thin adsorbed surfactant layer were developed. The addition of a thin layer of a viscous hydrocarbon liquid to the IRE surface was investigated as a model of a liquid-liquid interface (114) for studies of metal extraction ( Ni+2, Cu+2) by a hydrophobic chelating agent. The extraction of the metals from an aqueous buffer into the hydrocarbon layer was monitored kinetically by the appearance of bands unique to the complex formed. 

The reaction with C02, as reported for the dried aminosilane polymer also occurs with immobilized aminosilane molecules. Culler43 reported that approximately half of the amine groups are reacting with C02 when silica samples modified with APTS in aqueous solution, are dried in air. Comparison with AEAPTS and a triaminosilane showed that only primary amines react with C02. The reaction product is evidenced by FTIR bands at 1630, 1575, 1488 and 1332 cm 1. Also after modification in dry conditions and drying at room temperature in humid air, the reaction with C02 may be observed. Characteristic infrared bands appear upon modification at high concentrations of APTS. Figure 9.32 shows the infrared spectrum of dry silica, modified with a 10% APTS/toluene solution, after air drying for 30 minutes. 

Potassium tetrakis(l-pyrazolyl)borate is a white solid, m.p. 253-254°C. Its infrared spectrum is devoid of BH bands. This salt is quite soluble in dimethylformamide (DMF) and dimethyl sulfoxide but less so in water and alcohols. Stable 0.1 M aqueous solutions may be prepared and used as needed. 

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