Reagents potassium carbonate

The reagent must be carefully protected from moisture as it is comparatively easily hydrated to the acid, m.p. 216-218° (sealed capillary tube). Dilute aqueous solutions of an alcohol should be treated with solid potassium carbonate and the alcohol layer used for the test. 

A iridine traces in aqueous solution can be determined by reaction with 4-(p-nitroben25l)pyridine [1083-48-3] and potassium carbonate [584-08-7]. Quantitative determination is carried out by photometric measurement of the absorption of the blue dye formed (367,368). Alkylating reagents interfere in the determination. A iridine traces in the air can be detected discontinuously by absorption in Folin s reagent (l,2-naphthoquinone-4-sulfonate) [2066-93-5] (369,370) with subsequent chloroform extraction and hplc analysis of the red dye formed (371,372). The detection limit is ca 0.1 ppm. Nitrogen-specific thermal ionisation detectors can be used for continuous monitoring of the ambient air. 

This is followed by hydrolysi.s of the ester moieties with potassium carbonate and reesterification of the carboxy moiety with diazomethane to produce intermediate 65. The solitary free alcoholic hydroxyl at C-9 is oxidized with Collins reagent and the silyl ether groups are removed with acetic acid to give enprostil (63) [15]. 

Pyridinecarboxaldehyde (nicotinaldehyde) was supplied by Aldrich-Europe, Beerse, Belgium. The checkers purified this reagent by fractional distillation, b.p. 95-97° (15 mm.). The submitters stress that 3-pyridinecarboxaldehyde should be completely free from contamination by the acid. They stirred 150 g. of the aldehyde with 100 g. of potassium carbonate and 300 ml. of ethanol for 12 hours, filtered the suspended solid, and fractionally distilled the filtrate through a 30-cm. Vigreux column using a water aspirator. However, the checkers found that the recovery of aldehyde from this procedure was very low, and recommend vacuum distillation instead. 3-Pyridinecarboxaldehyde is a powerful skin irritant and should be handled with protective gloves. 

A reagent grade of pyridine, purchased from Fisher Scientific Company, was dried over anhydrous potassium carbonate and distilled. The pyridine was collected at 112-113°. 

It is not absolutely necessary to remove the last traces of water from the alcohol-carbon tetrachloride layer by means of potassium carbonate before returning it to the reaction mixture this process is, however, so simple and requires so little attention that there is no doubt that it is of material aid in cutting down the time of operation. The advantages of using crystallized oxalic acid and commercial 95 per cent alcohol, instead of the anhydrous reagents, are obvious. When technical oxalic acid is used, the yields are usually smaller by 5 to 10 per cent. 

Reagent grade, anhydrous potassium carbonate purchased from J. T. Baker Inc. was used. 

Acetic acid, potassium carbonate and ether are reagent grade. 

Aziridine synthesis can be achieved via nitrene addition to alkenes making use of a sulfonoxycarbamate [112]. Treatment of this reagent vith potassium carbonate in the presence of an alkene together with a PTC leads to the aziridine (Eq. 3.20). The reaction time is reduced from 2-3 h to 15 min when sonication is applied. 

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