Acetic anhydride, radioactive

Method. 1 mmole of compound is added to 1 ml of anhydrous pyridine in a S-ml flask. 2 mmoles of [I4C]acetic anhydride are then added for each expected reactive group (e.g., hydroxyl). The resulting mixture is heated at 12S °C for 4 h, cooled and poured into SO ml of cold water. This solution is transferred to a separating funnel and extracted with SO ml of diethyl ether. The diethyl ether is then washed three times with dilute hydrochloric acid, and once with each of dilute sodium hydroxide, water and saturated sodium chloride. The diethyl ether is dried with anhydrous sodium sulfate and evaporated to dryness for radioactive counting (using a proportional-flow counter or a scintillation counter). 

Decarboxylation methods failed. After several trials, excess phenylmagnesium bromide was used to form the tertiary alcohol, 459, which was treated with acetic anhydride containing a trace of sulfuric acid yielding the tetrasubstituted olefin, 460 (Scheme 56). This olefin was cleaved with ruthenium tetroxide and periodate. The resulting benzophenone was radioactive, thus the pathway to muurolene proceeds via cyclodecadiene as intermediate. 

S. Ruben, M.B. Allen, and P.J. Nahinsky, Tracer Studies with Radioactive Carbon. The Exchange between Acetic Anhydride and Sodium Acetate, Journal of the American Chemical Society 64, 3050-3053, 1942. 

Otvos, L., Marton, J., Meisel-Agoston, J. Investigations with radioactive acetic anhydride. I. On the mechanism of the Dakin-West reaction. II. The mechanism of the reaction between aromatic isocyanates and acid anhydrides. Acta Chim. Acad. Sci. Hung. 1960, 24, 327-331. Otvos, L., Marton, J., Meisel-Agoston, J. Investigations with radioactive acetic anhydride. I. On the mechanism of the Dakin-West reaction. Acta Chim. Acad. Sci. Hung. 1960, 24, 321-325. 

This step proceeds through the hydroxy-7V-acetate (418), which undergoes rearrangement in acetic anhydride-sodium acetate to give the iV-acetyl-acetate (419). Further simple steps afforded 1,2-didehydroaldosterone 18,21-diacetate (420), permitting tritiation to produce radioactive-labelled aldosterone. Several oxidations of the nitrone (417) are also described Jones chromic acid in aqueous acetone... 

In a series of papers Hall and co-workers have studied the oxidation of olefins over Pd and Pd-Au alloys, supported Ir," and unsupported Ag." The oxidation of ethylene over Pd and Pd-Au alloys produced the partial oxidation products acetic acid and acetic anhydride together with traces of ethylene oxide. Experiments with a reaction mixture containing [14-C]-acetaldehyde, in addition to ethylene and O2, showed that most of the radioactivity appeared in the acetic acid rather than the CO2. This was evi-... 

Both forms, however, contained intact RNA and the full complement of capsid polypeptides (50) Further evidence that a substantial conformational alteration of entero- and rhinovirus capsids accompanies the D to C antigenicity change has been obtained by examining the accessibilities of individual capsid proteins in intact virions, A-particles and naturally-occurring empty capsids to lacto-peroxidase-catalyzed iodination or alkylation with acetic anhydride (5I> 52). The results of these experiments are summarized in Table lY. Since under the experimental conditions employed the radioactive reagents formed covalent bonds with tyrosine residues... 

One milligram or less of a mixture of compounds is first treated with a radioactive reagent and the hot derivatives then fractionated. 3-Chloroanisoyl-3- Cl, 4-iodobenzoylchloride- 3H and, in particular, acetic anhydride-1- C or have been recommended as radioactive reagents... 

The procedures given here are suitable for labelling small amounts of inactive acids and alcohols by hot esterification. Acids are reacted with radioactive diazomethane, alcohols with radioactive acetic anhydride. 

It is frequently preferable to reduce acids or esters quantitatively to alcohols using lithium aluminium hydride and then to label these with radioactive acetic anhydride. 

H]Acetylarsanilic acid (AA) is prepared by mixing 0.1 mmole of [ H]acetic anhydride (50 mg, 25 mCi) with 4.9 mmoles of reagent grade acetic anhydride (460 mg) in 10 ml of dichloromethane and then allowing this solution to react with 1.7 mmoles of monosodium p-arsanilic acid (400 mg). The reaction mixture is immediately flash evaporated at room temperature until the solvent is completely removed and a white residue remains. The [ H]AA is precipitated with cold 1 N HCl and filtered the precipitate is washed twice sequentially with cold 95% ethanol, anhydrous ether, dried under reduced pressure, and stored at —20°. Thin-layer chromatography analysis of [ H]AA in butanol-acetic acid-water solvent system detected only a single radioactive fluorescent spot with an Rf value of 0.60. The specific radioactivity of [ HjAA is 12,000 cpm/nmole. Approximately 46% (185 mg) of [ H]AA was recovered. 

Optional, to reduce background from radioactive probes) Acetylate the preparation with acetic anhydride (5 ml/liter in 0.1 m triethanolamine [pH 8.0]). Place the slides in a rack and suspend in a dish over a magnetic stirring bar. Cover the slides with tri-ethanolmine and then add acetic anhydride while stirring. When acetic anhydride is completely dissolved, turn off the stirrer and let sit for 10 minutes. Dehydrate through ethanol as in step Ic. 

In mainstream organic synthesis acetylation is usually accomplished using acetic anhydride rather than the more reactive acetyl chloride. However, acetic anhydride has been much less used in carbon-14 synthesis because of the unavoidable loss of 50% of the radioactivity. Therefore, its use is limited to the labeling of substrates that have to be acylated either under very mild conditions or in very small quantities (e.g. proteins ), or to Perkin reactions, where its active methylene group is involved. 

Radioactive labeling of C-2 was effected by treating 4-amino-1,2,3-tri-azole-5-carboxamide with acetic formic anhydride (made from H C02H) and condensing the product with 2,3,5-tri-O-benzoyl-a-D-arabofuranosyl bromide. A final methanolysis gave a 53% yield of 9-a-D-arabinofuranosyl-8-azaadenine-2- C, with specific activity of 1.83 mCi/mmol. A similar... 

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