Oiganic acids

The oiganic acids are divided into three great classes, accord ing to th basicity. 

Types of catalysts used include mineral or oiganic acids and latent acids such as ammonurea salts, amine salts, and metal salts (49). One type of catalyst used in early commercial processing was amine hydrochloride. However, the fishy odor evolving from this material has caused this type of catalyst to be discarded. Metal salt catalysts such as magnesium chloride or zinc nitrate have been widely used over the years. However, because of effluent concerns, zinc salts have fallen into disuse. Magnesium nitrate has been suggested as an alternative catalyst (50). 

A report on the continuous flash pyrolysis of biomass at atmospheric pressure to produce liquids indicates that pyrolysis temperatures must be optimized to maximize liquid yields (36). It has been found that a sharp maximum in the liquid yields vs temperature curves exist and that the yields drop off sharply on both sides of this maximum. Pure cellulose has been found to have an optimum temperature for liquids at 500°C, while the wheat straw and wood species tested have optimum temperatures at 600°C and 500°C, respectively. Organic liquid yields were of the order of 65 wt % of the dry biomass fed, but contained relatively large quantities of oiganic acids. 

Lactulose. 4-0-p-D-Galactopyranosyl-4-D-fructofiiranose [4618-18-2] (Chronolac) (12) maybe made from lactose using the method described in Reference 9. It is a synthetic disaccharide that is not hydrolyzed by gastrointestinal enzymes in the small intestine, but is metabolized by colonic bacteria to short-chain organic acids. The increased osmotic pressure of these nonabsorbable oiganic acids results in an accumulation of fluid in the colon. Lactulose may not be tolerated by patients because of an extremely sweet taste. It frequently produces flatulence and intestinal cramps. 

Titanium whites resist various atmospheric contaminants such as sulfur dioxide, carbon dioxide, and hydrogen sulfide. Under normal conditions they are not readily reduced, oxidized, or attacked by weak inorganic and oiganic acids. Titanium dioxide dissolves slightly in bases, hydrofluoric acid, and hot sulfuric acid. Owing to its chemical inertness, titanium dioxide is a nontoxic, environmentally preferred white pigment. 

D. Blanco Gomis and J. J. Mangas Alonso, Analysis for Oiganic Acids. In Handbook of Food Analysis (Leo M. L. Nollet, ed.), Marcel Dekker, New York, Vol. 1, Chap. 19 (1996). 

Furfuryl alcohol is comparable to kerosene or No. 1 fuel oil in flammability, the Tag Closed Cup flash point is 170°F. In the presence of concentrated mineral acids or strong oiganic acids, furfuryl alcohol reacts with explosive violence. Therefore, precautions should be taken to avoid contact of such materials with the alcohol. Caution is also recommended to avoid over-catalysis in the manufacture of furfuryl alcohol resins. 

Uses. Although cyanoacetic acid can be used in applications requiring strong oiganic acids, its principal use is in the preparation of malonic esters and other reagents used in the manufacture of pharmaceuticals, eg, barbital, caffeine, and B vitamins (see Alkaloids Hypnotics Vitamins). Cyanoacetic acid can be used for the preparation of heterocyclic ketones. 

Direct-Flame Incinerators. In direct-flame incineration, the waste gases are heated in a fuel-fired refractory-lined chamber to the autoignition temperature where oxidation occurs with or without a visible flame. A fuel flame aids mixing and ignition. Excess oxygen is required, because incomplete oxidation produces aldehydes, oiganic acids, carbon monoxide, carbon soot, and other undesirable materials. 

Driers. These are generally soaps of cobalt, manganese, and other metals formed with oiganic acids such as linoleic, naphthenic, and other organic acids. They catalyze oxidation of drying oils (qv), and thus are used in inks that dry by oxidation (see Driers and METALLIC soaps). 

A continuous distillation process has been studied for the production of high boiling esters from intermediate boiling polyhydric alcohols and low boiling monocarboxylic aliphatic or aromatic acids (56). The water of reaction and some of the oiganic acid were continuously removed from the base of the column. 

Unsaturated Hydrocarbons. Olefins from ethylene through octene have been converted into esters via acid-catalyzed nucleophilic addition. With ethylene and propylene, only a single ester is produced using acetic acid, ethyl acetate and isopropyl acetate, respectively. With the butylenes, two products are possible jw-butyl esters result from 1- and 2-butylenes, whereas tert-butyl esters are obtained from isobutylene. The C5 olefins give rise to three JW-amyl esters and one /-amyl ester. As the carbon chain is lengthened, the reactivity of the olefin with oiganic acids increases. 

We thank Ken Mopper and A. Vairavamurthy for helpful discussions, Marcia House for help with oiganic acid analysis, and the National Science Foundation for financial support (Grant No. OCE-8516020). Contribution No. 622 from the University of Georgia Marine Institute. 

The most important industrial use of pentaerythritol is in a wide variety7 of paints, coatings, and varnishes, where the cross-linking capability of the four liy7droxy groups is critical. Alkyd resins (qv) are produced by reaction of pentaerythritol with oiganic acids such as phthalic acid or maleic acid and natural... 

Whereas metal salts of carboxylic acids catalyze the above reactions, these ate not sufficiently basic to cleave Si—H bonds. Mercury salts of oiganic acids in the presence of silver perchlorate, however, do react to produce organoacyloxysilanes (111). 

CE has been widely used for the analysis of metal ions generally with indirect UV detection. A recent volume of J. Chromatography (201 has covered developments and applications. Typically a small amine such as imidazole or benzylamine is added to the buffer to provide the background UV absorbance signal. Low-pH buffers are normally employed to suppress EOF flow and enhance resolution. Selectivity of metal ion separations can be modified (21 ( by the addition of small oiganic acids such as lactic or formic acid. 

In addition to the acid—base components shown in Figure 9, various oiganic acids are often found. Many of these acids are by-products of the atmospheric oxidation of organic matter released into the atmosphere. Of special interest are formic, acetic, oxalic, and benzoic acids, which have been found in rainwater in concentrations occasionally exceeding a few micromoles per liter. 

Corrosion Resistance. Zirconium is resistant to corrosion by water and steam, mineral acids, strong alkalies, oiganic acids, salt solutions, and molten salts (28) (see also Corrosion and corrosion control). This property is attributed to the presence of a dense adherent oxide film which forms at ambient temperatures. Any break in the film reforms instantly and spontaneously in most environments. 

---