Saturation of carbon

The stereoselectivity of different catalysts in catalytic hydrogenations is discussed in the chapter on catalysts (pp. 4, 50). In addition to catalytic hydrogenation, a few other methods of reduction can be used for saturation of carbon-carbon double bonds. However, their practical applications are no match for catalytic hydrogenation. 

The key variables influencing the color of semimoist pet foods are (1) the extent of saturation of carbon-monoxide-bonding sites, (2) the oxidation of iron in the meat protein, (3) the final concentration of meat or blood protein, and (4) the type of heat (dry or moist) and its process, which maintains the color of the carbon-monoxide-treated materials. The carbon monoxide treatment is indeed necessary to stabilize the color of the products (Hood, 1977). 

Carburization of substrates (Mo, W, Si, Fe/Si) leads to diamond nucleation enhancement due to the formation of carbides and the saturation of carbon at the substrate surface. 

Acetate of Potassa. Mix together 26 fluid ounces acetic acid with 12 fluid ounces distilled water add gradually 1 pound or more, undl saturation, of carbonate of potassa filter, and evaporate, by a sand-bath, to dryness. 

The usual conditions of catalytic hydrogenation can be applied, with certain modifications, for the saturation of carbon-carbon double and triple bonds. Platinum and Raney nickel are the usual catalysts described. It is important that catalysts used for deuteration shall be pretreated with deuterium noble-... 

Novello wine (or noveau) is obtained from the intracellular fermentation of the entire grapes placed in special stainless steel vats in absence of oxygen and saturated of carbon dioxide. This process is technically called carbonic maceration. The wine has normally a fiuity bouquet, a clean red colour and a fresh taste. 

Potassium hydroxide/benzyl alcohol Saturation of carbon-carbon double bonds s. 11,81... 

S = ultimate proportionate saturation of carbon (retentivity. fractional) W = weight of carbon, lb e = adsorption efficiency (fractional)... 

Figure 2.5 Saturation of carbon-fiber fabric of epoxy primer. Courtesy of Structural Technologies, LLC.

Reactions of Picric Acid, (i) The presence of the three nitro groups in picric acid considerably increases the acidic properties of the phenolic group and therefore picric acid, unlike most phenols, will evolve carbon dioxide from sodium carbonate solution. Show this by boiling picric acid with sodium carbonate solution, using the method described in Section 5, p. 330. The reaction is not readily shown by a cold saturated aqueous solution of picric acid, because the latter is so dilute that the sodium carbonate is largely converted into sodium bicarbonate without loss of carbon dioxide. 

Note, (i) Care should be taken to distinguish between a residue of carbon which may be very difficult to bum off completely, and a really non-volatile residue due to the presence of a metallic derivative. Thus for instance starch leaves a hard black residue of carbon which can best be burned away by moistening with a saturated solution of ammonium nitrate and then reheating. 

Hydrolysis (or saponification) of n-butyl acetate. Boil 4-5 g. of n-butyl acetate (Section 111,95) with 50 ml. of 10 per cent, sodium hydroxide solution under reflux until the odour of the ester can no longer be detected (about 1 hour). Set the condenser for downward distiUation and coUect the first 10 ml. of distillate. Saturate it with potassium carbonate, aUow to stand for 5 minutes, and withdraw all the Uquid into a small pipette or dropper pipette. AUow the lower layer of carbonate solution to run slowly into a test-tube, and place the upper layer into a small test-tube or weighing bottle. Dry the alcohol with about one quarter of its buUr of anhydrous potassium carbonate. Remove the alcohol with a dropper pipette and divide it into two parts use one portion for the determination of the b.p. by the Siwoloboff method (Section 11,12) and convert the other portion into the 3 5-dinitrobenzoate (Section III, 27) and determine the m.p. 

Boil 2 g. of the ester with 30 ml. of 10 per cent, sodium or potassium hydroxide solution under reflux for at least 1 hour. If the alcohol formed is water (or alkali) soluble, the completion of the hydrolysis will be indicated by the disappearance of the ester layer. Distil ofiF the liquid through the same condenser and collect the first 3-5 ml. of distillate. If a distinct la3 er separates on standing (or upon saturation of half the distillate with potassium carbonate), remove this layer with a capillary dropper, dry it with a little anhydrous potassium carbonate or anhydrous calcium sulphate, and determine the b.p. by the SiwoloboflF method... 

To hydrolyse an ester of a phenol (e.g., phenyl acetate), proceed as above but cool the alkaline reaction mixture and treat it with carbon dioxide until saturated (sohd carbon dioxide may also be used). Whether a solid phenol separates or not, remove it by extraction with ether. Acidify the aqueous bicarbonate solution with dilute sulphuric acid and isolate the acid as detailed for the ester of an alcohol. An alternative method, which is not so time-consuming, may be employed. Cool the alkaline reaction mixture in ice water, and add dilute sulphuric acid with stirring until the solution is acidic to Congo red paper and the acid, if aromatic or otherwise insoluble in the medium, commences to separate as a faint but permanent precipitate. Now add 5 per cent, sodium carbonate solution with vigorous stirring until the solution is alkaline to litmus paper and the precipitate redissolves completely. Remove the phenol by extraction with ether. Acidify the residual aqueous solution and investigate the organic acid as above. 

Protonation of formic acid similarly leads, after the formation at low temperature of the parent carboxonium ion, to the formyl cation. The persistent formyl cation was observed by high-pressure NMR only recently (Horvath and Gladysz). An equilibrium with diprotonated carbon monoxide causing rapid exchange can be involved, which also explains the observed high reactivity of carbon monoxide in supera-cidic media. Not only aromatic but also saturated hydrocarbons (such as isoalkanes and adamantanes) can be readily formylated. 

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