Infrared analysis solution

Assay of hydrogen cyanide can be done by specific gravity or silver nitrate titration. Sulfur dioxide in hydrogen cyanide can be deterrnined by infrared analysis or by reaction of excess standard iodine solution and titration, using standard sodium thiosulfate or by measurement of total acidity by... 

The time necessary for completion of the reaction may vary from 0.5 to 4 hours, depending on the actual activity of the alumina. The progress of conversion should be monitored by infrared analysis of a concentrated sample of the solution. Stirring should be continued for 15 minutes after the nitroso band at 1540 cm. has disappeared. A strong diazo band at about 2100 cm. will then be present. The carbonyl band at 1750 cm. initially due to nitrosocarbamate, will usually not disappear completely during the reaction, because some diethyl carbonate is formed in addition to carbon dioxide and ethanol. Diethyl carbonate is removed during the work-up procedure. 

Estrone methyl ether (100 g, 0.35 mole) is mixed with 100 ml of absolute ethanol, 100 ml of benzene and 200 ml of triethyl orthoformate. Concentrated sulfuric acid (1.55 ml) is added and the mixture is stirred at room temperature for 2 hr. The mixture is then made alkaline by the addition of excess tetra-methylguanidine (ca. 4 ml) and the organic solvents are removed. The residue is dissolved in heptane and the solution is filtered through Celite to prevent emulsions in the following extraction. The solution is then washed threetimes with 500 ml of 10 % sodium hydroxide solution in methanol to remove excess triethyl orthoformate, which would interfere with the Birch reduction solvent system. The heptane solution is dried over sodium sulfate and the solvent is removed. The residue is satisfactory for the Birch reduction step. Infrared analysis shows that the material contains 1.3-1.5% of estrone methyl ether. The pure ketal may be obtained by crystallization from anhydrous ethanol, mp 99-100°. Acidification of the methanolic sodium hydroxide washes affords 10-12 g of recovered estrone methyl ether. 

Spectra of solution cast films of the hydrogenated NBR were recorded on a Nicolet 520 FT-IR spectrophotometer. The final degree of olefin conversion was confirmed by infrared analysis.9... 

By studying the changes in pH during reaction, and by following species from infrared analysis of the solution, Scheme 7 was proposed for the mechanism, using Fe carbonyl as the catalyst ... 

Solimani, R., The flavonols quercetin, rutin and morin in DNA solution UV-vis dichroic (and mid-infrared) analysis explain the possible association between the biopolymer and a nucleophilic vegetable-dye, Biochim. Biophys. Acta, 1336, 281, 1997. 

Acetyl peroxide was recrystallized three times at —78°C. to give a stock solution of peroxide in isooctane, whose concentration was determined either by infrared analysis using the 1790 cm."1 peroxide band or by iodometric titration (13). 

The degree of neutralization may be measured by several techniques. Infrared analysis may be employed and the degree of neutralization calculated from the changes resulting in the absorption bands. Another method comprises the titration of a solution of the ionic copolymer with a strong base. 

Kreher and Jager have studied the aluminum chloride catalyzed decomposition of azidoformates in several solvents.18118 They reasonably assumed that the decomposition process in n-hexane and nitromethane solution proceeds by C02 elimination and the formation of alkyl azides which then decompose into imines (eq 5). Furthermore, infrared analysis has shown that the catalyst is fixed at the carbonyl group of the azido-formate. 

A gas-washing bottle (Figure 4.7B) may also be used for trapping. This technique is especially useful in conjunction with infrared analysis. The sample is simply bubbled through the anhydrous solvent as it exits the chromatographic column. The solution is then placed in a liquid sample infrared cell. A matching cell containing only the solvent is placed in the reference beam. An infrared spectrum of the sample may then be recorded. 

The semi-hydrogenated acetate coupled product was dissolved in a 1% solution of sodium hydroxide in methyl alcohol. The solution was allowed to stand about 12 hours at room temperature under a blanket of nitrogen. The hydrolysis was complete as shown by the total absence of ester bands in an infrared analysis. 

Two grams of HSPAN was added to 500 ml of water, the pH was adjusted from 9 to 6.5 with dilute hydrochloric acid, and 0.1 ml of Thermamyl 60L enzyme solution (Novo Enzyme Corp.) was added. The resulting mixture was heated at 95°C for 21 hr, and the clear yellow solution was exhaustively dialyzed against distilled water. Freeze drying yielded 1.235 g of polymer, which contained only about 5% residual carbohydrate (by infrared analysis). The number average molecular weight of this polymer was 44,000, as determined in 0.15N sodium chloride solution on a Melabs Model CSM-2 membrane osmometer equipped with a B-19 membrane (Schleicher and Schuell Co.). 

Infrared Analysis. Polymer solutions of about 1% concentration were prepared in spectroscopic grade chloroform. The absorbance of the band at 5.8/x (C=0 stretching vibration) was measured on an Infracord 137 as a function of polymer concentration and of cell path length. This gave an apparent extinction coefficient for each polymer. From the results of the chemical analyses, the following equation was obtained, which relates the apparent extinction coefficient to the copolymer composition ... 

Treatment with fuming sulfuric acid produces an irreversible change in BBB but has no effect on BBL if the polymer is cyclized completely to give the structure indicated above. Further condensation may occur in solution in fuming sulfuric acid if the BBL is not formed completely before dissolution. Infrared analysis of the acid-treated BBB after precipitation in water shows the presence of sulfone and sulfonate groups, and gravimetric analysis shows that the polymer contains one sulfur... 

The polyformal (I) was characterized by wet chemical and infrared analyses, and by cryoscopic molecular weight determinations. For the latter, the preferred method was the freezing point depression of an ethylene bromide solution. The other polyacetals were characterized primarily by infrared analysis and molecular weight determinations. 

The ether-benzene solution was dried first over Drierite and then over anhydrous sodium sulfate and distilled at atmospheric pressure. The flask was heated in a bath at 55°-60° C. throughout distillation of the bulk of the solvents and raised to 95°--100o C. for 20 min. at the end. The distillate, collected at dry ice temperature, was shown by infrared analysis to consist of unreacted eft-butyldifluoramine and ethyl ether. A residue... 

In an attempt to prepare polycyclopentadiene which would be stable in toluene solution, the polymer was hydrogenated over a platinum oxide catalyst in a Parr bomb immediately after the completion of the polymerization reaction. Infrared analysis indicated the presence of residual unsaturation and the polymer became insolubilized on standing. An attempted copolymerization of cyclo-pentadiene with propylene gave a product whose infrared spectrum indicated the presence of C-methyl groups but which was still insoluble in toluene. No attempt was made to determine whether copolymerization had occurred. 

---