Sodium acetate azide

Singlet oxygen [Oxygen, singlet], 51 Sodium acetate [Acetic acid, sodium salt], 33,49,66 Sodium azide, 109 Sodium hydride, 20 Sodium thiosulfate (Thiosulfuric acid (HjSj03), disodium salt], 120 Squalene [2,6,10,14,18,22 Tetracosa-... 

AH substrates (varying between 0.018 and 0.05% w/v) were incubated in 50 mM sodium acetate buffer pH 5.0, containing 0.01% w/v sodium azide, at 40 °C for 24 h. RGO s were treated with 2.6 pg RG-gaiacturonohydrolase per mg substrate. When RGO s were sequentially treated with the exo-enzymes to form smaller oligomers, the RG-galacturonohydrolase and the RG-rhamnohydrolase were used in amounts between 2.4 and 2.8 pg and between 9 and 18 pg per mg substrate respectively. RGO s were incubated with 0.18 pg RG-hydrolase and with 0.42 pg RG-lyase per mg substrate. Subsequent incubation of the RG-hydrolase/RG-lyase digest with the exo-enzymes was carried out with 6 pg of RG-galacturonohydrolase and with 16 pg RG-rhamnohydrolase per mg substrate. 

The title compounds were prepared safely by a diazo-transfer reaction onto f3-oxosulfones by treatment with l-ethyl-2-chloropyridinium tetrafluoroborate and sodium azide in presence of sodium acetate. 

Three gradients of 0.0-0.5 M sodium chloride were run consecutively at 4°C in 0.05 M sodium acetate-acetic acid, 1 mM sodium azide, pH 5.25, followed by 0.05 M sodium acetate-acetic acid, 1 mM sodium azide, pH 3.5, and finally by 0.05 M sodium dihydrogen phosphate-disodium hydrogen phosphate (approx. 1 3), 1 mM sodium azide, pH 7.0. After sample application, the column was washed with the starting buffer to remove any non-bound compounds. Elution was continued with the high salt buffer. Fractions of 4 ml were collected and assayed for reactivity towards ninhydrin and for electric conductivity (salt concentration) after 75-fold dilution of a 100-pl aliquot. Ninhydrin-positive fractions were pooled for each peak, concentrated, and desalted by size exclusion chromatography (see above). 

The synthesis of valsartan (2) by Novartis/Ciba-Geigy chemists is highlighted in Scheme 9.5. Biphenylbenzyl bromide 18 is converted to biphenyl acetate 19 in the presence of sodium acetate in acetic acid. Hydrolysis of 19 followed by Swern oxidation delivered the biphenyl aldehyde 20, which underwent reductive amination with (L)-valine methyl ester (21) to give biphenyl amino acid 22. Acylation of 22 with penta-noyl chloride (23) afforded biphenyl nitrile 24, which is reacted with tributyltin azide to form the tetrazole followed by ester hydrolysis and acidihcation to provide valsartan (2). [See Biihlmayer et al. (1994, 1995).]... 

Lead azide is insoluble in an aqueous solution of ammonia. Acetic acid causes its decomposition but it is soluble in water and concentrated solutions of sodium nitrate, sodium acetate or ammonium acetate. There are fairly big differences of solubility, depending on temperature. 

Lithium aluminium hydride reduction of 235 followed by mesylation afforded 236. The latter was oxidized with osmium tetroxide and sodium metaperiodate to yield the cyclobutanone 237. Treatment of 237 with acid afforded in 48% yield the ketoacid (238), which was esterified with diazomethane to 239. The latter was converted to the ketal 240 by treatment with ethylene glycol and /7-toluenesulfonic acid. Compound 240 was reduced with lithium aluminium hydride to the alcohol 241. This alcohol had been synthesized previously by Nagata and co-workers (164) by an entirely different route. The azide 242 was prepared in 80% yield by mesylation of 241 and treatment of the product with sodium azide. Lithium aluminium hydride reduction of 242 gave the primary amine, which was converted to the urethane 243 by treatment with ethyl chloroformate. The ketal group of 243 was removed by acidic hydrolysis and the resulting ketone was nitro-sated with N204 and sodium acetate. Decomposition of the nitrosourethane with sodium ethoxide in refluxing ethanol afforded the ketone 244 in 65% yield. The latter had been also synthesized previously by Japanese chemists (165). The ketone 244 was converted to the ketal 246 and the latter to 247... 

The mixture 258 was converted to the unstable benzenesulfonyl aziridine 259 by treatment with an excess of benzenesulfonyl azide in benzene. Ace-tolysis of 259 with acetic acid and sodium acetate at room temperature for several days afforded the crystalline mixture of diastereoisomers represented by the formula 260. The aziridine rearrangement was regiospecific and 260 was the only product detected during this rearrangement. Lithium aluminium hydride reduction of 260 followed by acetylation yielded the mixture 261 in 85% yield. Selective hydrolysis of 261 afforded 262 in quantitative yield. The diastereoisomeric mixture 262 was converted into the diols 263 by hydrogenolysis. The diol mixture was oxidized with chromium trioxide... 

Carboxymethylcellulose slurry (equivalent of 75 g of dry material)—Slowly wet 75 g of dry resin in distilled water. Draw off the supernatant (after the resin has settled) with vacuum filtration. Resuspend the filtered resin cake in 1.5 L of 0.5 M NaOH (30 g of NaOH dissolved in 1.5 L of distilled water). Allow the resin to settle, draw off the supernatant, and wash the resin cake twice, as before, in 2.5 L volumes of distilled water. Resuspend the resin cake in 2.5 L of 0.5 M HC1 (100 ml of concentrated HC1 in 2.4 L of distilled water). Allow the resin to settle, draw off the supernatant, and wash the resin cake twice, as before, in 2.5 L volumes of distilled water. Repeat the wash procedure described above with 1.5 L volumes of 0.03 M sodium acetate buffer, pH 5.0, until the pH and ionic strength of the drawn-off supernatant is the same as that of the sodium acetate buffer (pH and conductivity meter). Resuspend the resin cake in 1.5 L 0.03 M sodium acetate buffer, pH 5.0. Add 2 g/liter sodium azide for storage to prevent bacterial growth. Remove the azide by washing again in 0.03 M sodium acetate buffer, pH 5.0 when it is ready to be used by the class. 

The mobile polar phase was an aqueous buffer (sodium acetate-Veronal buffer 1/7M at pH 7.4) alone or mixed with various quantities of acetone. The compounds were dissolved in water, acetone, or ethanol (1—3 mg/ml) and spotted in 1 jaliter amounts. The spots were detected by an alkaline solution of potassium permanganate. The penicillins could be detected also by iodine azide solution. 

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