Steam volatile acids

Distillate. This will contain the steam-volatile acidic and neutral com ponents present. Render alkaline with 10 20% NaOH and distil. 

In the first place, Stadie, Zapp and Lukens67 failed to obtain any evidence for the production of acetic acid or any other steam-volatile acids in liver slices of depancreatized cats. These authors state further that no evidence could be found in the literature for the production of acetic acid in the livers of normal or diabetic animals except for the report of Cook and Harrison.68 They believe that the acetic acid, which... 

Distillate. This will contain the steam-volatile acidic and neutral com ponents present. Render alkaline with 10-20% NaOH and distil. Aqueous acid solution (f ,). Render alkaline with 10-20% NaOH and distil. ... 

Burdick, D., R.L. Stedman, and 1. Schmeltz Distribution of steam-volatile acidic substances in cigarette smoke 17th Tobacco Chemists Research Conference, Program Booklet and Abstracts, Vol. 17, Paper No. 14, 1963, p. 

Quin, L.D., P. Wilder, and M.E. Hobbs Chromatographic determination of steam-volatile acids in cigarette smoke ... 

Schmeltz, 1., R.L. Stedman, and R.L. Miller Steam-volatile acids from various tobaccos 17th Tobacco Chemists Research Conference, Program Booklet and Abstracts, Vol. 17, Paper No. 13, 1963, pp. 11-12 Composition studies on tobacco. XVI. Steam volatile acids J. Assoc. Off. Anal. Chem. 46 (1963) 779-784. Schmeltz, 1., C.D. Stills, W.J. Chamberlain, and R.L. Stedman Analysis of cigarette smoke fractions by combined gas chromatography-infrared spectrophotometry Anal. Chem. 37 (1965) 1614-1616. 

Stedman, R.L., D. Burdick, W.J. Chamberlain, and I. Schmeltz Composition studies on tobacco. XVIII. Steam-volatile acids in smoke of cigarettes having different organoleptic properties Tob. Sci. 8 (1964) 79-81. Stedman, R.L., D. Burdick, and I. Schmeltz Composition studies on tobacco. XVII. Steam-volatile acidic fraction of cigarette smoke Tob. Sci. 7 (1963) 166-169. 

Note 7. Volatile acids in digestion mixture. It has been found that traces of steam volatile acids remain in the acid digestion mixture after digestion of certain organic materials. These are removed by passing steam through the diluted digestion mixture prior to sodium hydroxide addition. This acidic distillate is rejected. 

Hydrolysis of a sulphonamide. Mix 2 g. of the sulphonamide with 3-5 ml. of 80 per cent, sulphuric acid in a test-tube and place a thermometer in the mixture. Heat the test-tube, with frequent stirring by means of the thermometer, at 155-165° until the solid passes into solution (2-5 minutes). Allow the acid solution to cool and pour it into 25-30 ml. of water. Render the resulting solution alkaline with 20 per cent, sodium hydroxide solution in order to liberate the free amine. Two methods may be used for isolating the base. If the amine is volatile in steam, distil the alkaline solution and collect about 20 ml. of distillate extract the amine with ether, dry the ethereal solution with anhydrous potassium carbonate and distil off the solvent. If the amine is not appreciably steam-volatile, extract it from the alkaline solution with ether. The sulphonic acid (as sodium salt) in the residual solution may be identified as detailed under 13. 

Step 3. The non-steam-volatile compounds. The alkaline solution (82) remaining in the distiUing flask from Step 2 may contain water-soluble, non-volatile acidic, basic or neutral compounds. Add dilute sulphuric acid until the solution is just acid to Congo red, evaporate to dryness, and extract the residual solid with boiling absolute ethyl alcohol extraction is complete when the undissolved salt exhibits no sign of charring when heated on a metal spatula in the Bunsen flame. Evaporate the alcoholic solution to dryness and identify the residue. 

The impurities present in aromatic nitro compounds depend on the aromatic portion of the molecule. Thus, benzene, phenols or anilines are probable impurities in nitrobenzene, nitrophenols and nitroanilines, respectively. Purification should be carried out accordingly. Isomeric compounds are likely to remain as impurities after the preliminary purifications to remove basic and acidic contaminants. For example, o-nitrophenol may be found in samples ofp-nitrophenol. Usually, the ri-nitro compounds are more steam volatile than the p-nitro isomers, and can be separated in this way. Polynitro impurities in mononitro compounds can be readily removed because of their relatively lower solubilities in solvents. With acidic or basic nitro compounds which cannot be separated in the above manner, advantage may be taken of their differences in pK values (see Chapter 1). The compounds can thus be purified by preliminary extractions with several sets of aqueous buffers... 

Boric acid (boracic acid) [10043-35-3] M 61.8, m 171 , pK 9.23. Crystd three times from H2O (3mL/g) between 100° and 0°, after filtering through sintered glass. Dried to constant weight over metaboric acid in a desiccator. It is steam volatile. After 2 recrystns of ACS grade it had Ag at 0.2 ppm. 

Oxygen is not the only noncondensable gas found in boiler circuits, Problems occur due to the presence of carbon dioxide (C02). Carbon dioxide is steam-volatile and reacts with condensing steam to produce carbonic acid, which attacks steel condensate return lines. 

N-Nitrosamine inhibitors Ascorbic acid and its derivatives, andDC-tocopherol have been widely studied as inhibitors of the N-nitrosation reactions in bacon (33,48-51). The effect of sodium ascorbate on NPYR formation is variable, complete inhibition is not achieved, and although results indicate lower levels of NPYR in ascorbate-containing bacon, there are examples of increases (52). Recently, it has been concluded (29) that the essential but probably not the only requirement for a potential anti-N-nitrosamine agent in bacon are its (a) ability to trap NO radicals, (b) lipophilicity, (c) non-steam volatility and (d) heat stability up to 174 C (maximum frying temperature). These appear important requirements since the precursors of NPYR have been associated with bacon adipose tissue (15). Consequently, ascorbyl paImitate has been found to be more effective than sodium ascorbate in reducing N-nitrosamine formation (33), while long chain acetals of ascorbic acid, when used at the 500 and lOOO mg/kg levels have been reported to be capable of reducing the formation of N-nitrosamines in the cooked-out fat by 92 and 97%, respectively (49). 

Acetic acid (b.p. 118 °C) is not boiled off from open dyebaths as readily as ammonia but is rapidly flashed off in steam or dry heat processes, thus developing the maximum degree of alkalinity under these conditions. The sodium salts of less volatile acids, such as sodium citrate, can be used to develop a lower degree of alkalinity. 

All the present evidence points to phytotoxic steam-volatile fatty acids/ particularly acetic, being a major microbiological factor responsible for the crop damage, and the conditions of ecological significance referred to earlier have been satisfied. However, the toxin is produced only in the straw tissue and its concentration declines exponentially with distance from the straw (13). A correlation of soil acetic acid content with phytotoxicity is therefore neither expected nor found. 

The steam-volatility of isomeric thienothiophenes allows separation from the resinous products formed during their synthesis from citric acid or acetylene. Selenophenoselenophenes are also steam-volatile. It is, however, very difficult to separate the isomeric thienothiophenes from each other and from benzo[b]thiophene with which they are also... 

The current method (3, 4, 6, 22) involves steam distillation to separate the volatile (primarily acetic) acids from the non-volatile (fixed) acids. Special equipment has been devised for this separation (6). Sulfurous and sorbic acid content can be corrected, or the sulfurous acid may be removed (33). Carbon dioxide must be removed so that it does not interfere with the test (6, 33). An automated procedure is also available (34) which measures the volatile acids in the distillate at 450 nm using bromophenol blue. 

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