Citric acid and derivatives

Citric acid and derivs 3 C324 citric acid azide 3 C324 citric acid nitrate 3 C324... 

Citric acid and other hydroxycarboxylic acids, such as gluconic acid. Also, derivatives such as sodium gluconate (D-gluconic acid, sodium salt), HOCH2[CH(OH)]4 COONa. 

Soon after thiophene and its derivatives had been prepared by treating 1,4-dicarbonyl compounds with P2S3, Biedermann and Jacobson extended this procedure to citric and tricarballylic acids. By heating a mixture of citric acid and PjSj, they obtained a compound CJH4S2, b.p. 224°-226°, in about 1% yield. The structure 1 was ascribed to this compound, which was called thiophthene [Eq. (1)]. 

The removal of the TMS group is commonly carried out in the presence of a catalyst including iron(III) and tin(II) chlorides, copper(II) nitrate, cerium(III) nitrate, citric acid and sodium hydroxide or various fluoro derivatives. TMS derivatives are rather easily hydrolyzed to their alcohol precursors, but the bulkier silyl ethers are more resistant and are stable over a wide pH range. These protective groups are readily cleaved by fluoride anion, often introduced as a tetraalkylammonium salt such as tetrabutylammonium fluoride (TBAF). 

Some of the com-derived glucose goes into various fermentation processes that lead to other chemical products. For example, large-scale production was recently announced for lactic acid and polylactide plastic derived from it. Citric acid and lysine are two other important fermentation products. 

Derivation Interaction of bismuth subnitrate, citric acid, and ammonium hydroxide. 

Derivation By heating dehydrated citric acid and concentrated sulfuric acid together. 

Derivation Reaction of citric acid and magnesium hydroxide or carbonate. 

A method of esterification introduced by Meyer807 is to dissolve the carboxylic acid in an excess of concentrated sulfuric acid (if necessary with warming) and to treat the solution cautiously with a small excess of the requisite alcohol when the reaction, which is often violent, ceases—if the mixture does not become warm, it must be heated—the solution is poured on solid sodium carbonate and worked up. This method has been used for esterification of sterically hindered acids and for carboxy derivatives of nitrogenous heterocycles, also for preparation of acetonedicarboxylic esters from citric acid and alcohols.808... 

The plant contains iridoid glycosides asperuloside (120) monotropein and aucubin (19), phenolic acids caffeine, gallic acid, anthraquinone derivatives, flavonoids, coumarins, citric acid and red dye. It has been employed in the form of an infusion, as aperient, diuretic, refrigerant, alternative and antiscorbutic. Extract of leaves used as astringent, plant paste applied on skin disease [69,153]. 

Figure 1 shows the results of TGA studies of these two precursors. The precursors derived from citric acid and EDTA display a similar curve shape, suggesting that a similar pyrolysis process occurs for these solids In the presence of air. Both precursors show weight losses In three distinct regions. A gradual wel t loss Is first observed above ca. 150 "c. This Is followed by a sharp weight loss at 360 - 450 C. The third wel t loss occurs In the range 750 - 810 °C. 

A study of the relaxational transitions and related heat capacity anomalies for galactose and fructose has been described which employs calorimetric methods. The kinetics of solution oxidation of L-ascorbic acid have been studied using an isothermal microcalorimeter. Differential scanning calorimetry (DSC) has been used to measure solid state co-crystallization of sugar alcohols (xylitol, o-sorbitol and D-mannitol), and the thermal behaviour of anticoagulant heparins. Thermal measurements indicate a role for the structural transition from hydrated P-CD to dehydrated P-CD. Calorimetry was used to establish thermodynamic parameters for (1 1) complexation equilibrium of citric acid and P-CD in water. Several thermal techniques were used to study the decomposition of p-CD inclusion complexes of ferrocene and derivatives. DSC and derivative thermogravimetric measurements have been reported for crystalline cytidine and deoxycytidine. Heats of formation have been determined for a-D-glucose esters and compared with semiempirical quantum mechanical calculations. ... 

Aliphatic polyamides derived from citric acid and lysine... 

Boustta, M., Huguet, J., and Vert, M., 1991, New functional polyamides derived from citric acid and L-lysine Synthesis and characterization, Makromol. Chem., Macromol. Symp., 47 345-355... 

Recently, a study by EPA (Environmental Protection Agency) in the USA, dated November 2001, has revealed that isodecy 1 benzoate does not pose an unacceptable risk to human health. In this respect, it is also worth mentioning a report issued by the Danish EPA in 2001, in which different plasticizers are recommended for different purposes. Table 13.2 points out to substitute phthalates in toys by a derivative of citric acid and contains many other suggestions. 

In this example two oxygens are replaced by the single group C4H4 (C2H4 if C = i2) and 2OH disappear with the oxygen outside the C2O2 radical. From three molecules of carbonic acid, a molecule of citric acid is derived ... 

Differentiate the 2 and expressions in equation (5-4) with respect to H. Then put in the K values for citric acid and find the H at the maxima by setting the derivatives equal to zero. 

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