Citric acid aliphatic

Two-Phase Citric Acid-Aliphatic Alcohol-Water Systems... 

Two-Phase Citric Acid Aliphatic Alcohol-Water Systems but using Eq. (2.121) we have at constant T... 

Chapter 2 is devoted to properties of solid citric acid and aqueous and orgartic solutions of it. Detailed phase equilibria in the citric acid + water system (melting, freezing, boiling, solubilities and vapour pressures curves) are presented, correlated and thermodynamically analyzed. Dynamic and other physical properties (viscosities, diffusion coefficients, thermal and electrical conductivities, surface tensions and indices of refraction) are examined. Solubihties of citric acid in organic solvents and ternary citric acid + aliphatic alcohol + water and citric add + tertiary amine + water systems are also discussed. 

If a phenol is not indicated, the solution may contain an aliphatic acid. Transfer to a distilling-flask, make definitely acid with dih H2SO4, and distil the volatile formic and acetic acids if present will distil over. If the distillation gives negative reactions, test the residual solution in the flask for oxalic, succinic, lactic, tartaric and citric acids and glycine, remembering that the solution is strongly acid. 

Such materials are soluble in the lower aliphatic alcohols, e.g.ethanol, and in phenols. They also absorb up to 21 % of moisture when immersed in water. If this material is heated with 2% citric acid at elevated temperatures, typically for 20 minutes at 120°C, cross-linking will take place Figure 18.20). 

The most common types of plasticizer are the phthalic acid esters of Cg, Cio alcohols citric acid esters and epoxy aliphatic esters. 

Yang and coworkers did the most efforts on the development of network polyester based on citric acid. " They investigated the reaction of citric acid with a series of aliphatic diols (from 3-16 carbon chains) and polyether diols such as polyethylene oxide (PEG), in which 1,8-octanediol (POC) and 1,10 decanediol (PDC) have been studied the most. 

The carboxylic acids formed in this way are themselves a source of other aliphatic compounds, so that free carbon acids above C-10 are found only in traces.3 Citric acid yields itaconic acid and citraconic acid during... 

Formulated metal polishes consist of fine abrasives similar to those involved in industrial buffing operations, ie, pumice, tripoli, kaolin, rouge and crocus iron oxides, and lime. Other ingredients include surfactants (qv), eg, sodium oleate [143-19-1] or sodium dodecylbenzenesulfonate [25155-30-0]-, chelating agents (qv), eg, citric acid [77-92-9] and solvents, eg, alcohols or aliphatic hydrocarbons. 

The application of cellulosic anion exchanger in the separation of trace amounts of rare earths has also been investigated. Diethylaminoe-thyl cellulose paper and 0.026M citric acid were found to be the most satisfactory. A separation factor of 2.6 between Eu and Ce was obtained [123]. It has been found [124] that a mixture of HC1 and various aliphatic alcohols can be successfully used as eluant for the separation of rare earths by paper chromatography (Whatman No. 1). 

Contaminants and by-products which arc usually present in 2- and 4-atninophenol made by catalytic reduction can be reduced or even removed completely by a variety of procedures These include treatment with 2-propanol, with aliphatic, cycloaliphatic, or aromatic ketones, with aromatic amines, with loluene or low mass alkyl acetates, or with phosphoric acid, hydroxyacetic acid, hydroxypropionic acid, or citric acid. In addition, purity may be enhanced by extraction with methylene chloride, chloroform, or nitrobenzene. Another method employed is the treatment of aqueous-solutions of aminophenols with activated carbon. 

The procedure towards an environmentally benign process starts with the selection of raw materials in addition to conventional raw materials from the petrochemical industry based on low- to medium-boiling aliphatic and aromatic hydrocarbons, replenishable raw materials from nature are increasingly available nowadays. In the simplest cases, these can be carbon sources, such as glucose and sucrose for fermentation, but also more complex molecules, frequently obtained from the chiral pool or through inexpensive fermentation from carbon sources, such as glutamic acid or citric acid. Table 20.2 lists a selection of raw materials from the chiral pool, with their estimated costs per kilogram. 

Fatty acid degradation and synthesis are relatively simple processes that are essentially the reverse of each other. The process of degradation converts an aliphatic compound into a set of activated acetyl units (acetyl CoA) that can be processed by the citric acid cycle (Figure 22.2). An activated fatty acid is oxidized to introduce a double bond the double bond is hydrated to introduce an oxygen the alcohol is oxidized to a ketone and, finally, the four carbon fragment is cleaved by coenzyme A to yield acetyl CoA and a fatty acid chain two carbons shorter. If the fatty acid has an even number of carbon atoms and is saturated, the process is simply repeated until the fatty acid is completely converted into acetyl CoA units. 

The resulting products are citric acid and a fatty acid reduced in length by two carbons. It is postulated that the remaining aliphatic acid after subsequent oxidation to the corresponding /3-keto acid undergoes a similar condensation. In this manner the complete breakdown of fatty acid chains is explained. 

Esters. Aliphatic acids including a-amino acids and citric acid form methyl esters selectively (in the presence of aromatic acids) and in excellent yields when treated with... 

Aliphatic tricarboxylic acids such as citric acid exhibit a remarkably high affinity toward the stationary phase of an anion exchanger. Hence, low ionic strength bicarbon-ate/carbonate buffer solutions are not particularly suited as eluents. However, when a sodium hydroxide solution at a comparatively high concentration (c 0.08 mol/L) is used, citric acid may be eluted, and may even be separated from its structural isomer isocitric acid. When the detection of these compounds is carried out via electrical con-... 

Blanc (1979) considered that the organoleptic influence of carboxylic acids in coffee was undeniable but that numerous difficulties continue to exist concerning their quantitative evaluation. He used specific enzymic methods to determine the contents of citric acid (E.57), malic acid (E.53), lactic acid (E.30), pyruvic acid (E.38) and acetic acid in aqueous extracts of roasted coffees over a range of different degrees of roasting. He asserted that the assembly of these five acids represented the main part of the aliphatic carboxylic acid fraction. 

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