Succinic acid dehydration

N). This area of the process has received considerable attention in recent years as companies strive to improve efficiency and reduce waste. Patents have appeared describing addition of SO2 to improve ion-exchange recovery of vanadium (111), improved separation of glutaric and succinic acids by dehydration and distillation of anhydrides (112), formation of imides (113), improved nitric acid removal prior to dibasic acid recovery (114), and other claims (115). 

Pyrrohdinone (2-pyrrohdone, butyrolactam or 2-Pyrol) (27) was first reported in 1889 as a product of the dehydration of 4-aminobutanoic acid (49). The synthesis used for commercial manufacture, ie, condensation of butyrolactone with ammonia at high temperatures, was first described in 1936 (50). Other synthetic routes include carbon monoxide insertion into allylamine (51,52), hydrolytic hydrogenation of succinonitnle (53,54), and hydrogenation of ammoniacal solutions of maleic or succinic acids (55—57). Properties of 2-pyrrohdinone are Hsted in Table 2. 2-Pyrrohdinone is completely miscible with water, lower alcohols, lower ketones, ether, ethyl acetate, chloroform, and benzene. It is soluble to ca 1 wt % in aUphatic hydrocarbons. 

Succinic anhydride [108-30-5] (3,4-dihydro-2,5-furandione butanedioic anhydride tetrahydro-2,5-dioxofuran 2,5-diketotetrahydrofuran succinyl oxide), C H O, was first obtained by dehydration of succinic acid. In the 1990s anhydride is produced by hydrogenation of maleic anhydride and the acid by hydration of the anhydride, by hydrogenation of aqueous solutions of maleic acid, or as a by-product in the manufacture of adipic acid (qv) (see Maleic ANHYDRIDE, MALEIC ACID, AND FUMARIC ACID). 

The acid occurs both as colorless triclinic prisms (a-form) and as monoclinic prisms ( 3-form) (8). The P-form is triboluminescent and is stable up to 137°C the a-form is stable above this temperature. Both forms dissolve in water, alcohol, diethyl ether, glacial acetic acid, anhydrous glycerol, acetone, and various aqueous mixtures of the last two solvents. Succinic acid sublimes with partial dehydration to the anhydride when heated near its melting point. 

Heat. When heated, succinic acid loses water and forms an internal anhydride with a stable ring stmcture. Dehydration starts at 170°C and becomes rapid at 190—210°C (25). Further heating of succinic anhydride causes decarboxylation and the formation of the dilactone of gamma ketopimelic acid (26) (eq. 1). The same reaction takes place at lower temperatures in the presence of alkaU. 

Hydration and Dehydration. Succinic anhydride reacts slowly with cold water and rapidly with hot water to give the acid. For this reason it must be carefully stored in anhydrous conditions. Succinic acid can be dehydrated to the anhydride by heating at 200°C, optionally in the presence of a solvent (31). Dehydration can also be performed with clay catalysis in the presence of isopropenyl acetate under microwave irradiation (32) or with his (trichi oromethyl) carbonate at room temperature (33). 

Various techniques have been proposed for the recovery of pure succinic acid, including extraction (141—145), selective crystalliza tion (146—151), heating to dehydrate the acid and subsequent recovery of succinic anhydride by distillation (152), esterification foUowed by fractionation of the mixture of the esters (65—69), and separation as urea adduct (118,119). 

Succinic anhydride can be prepared from succinic acid by dehydration it operates in high boiling solvent (31), in the presence of clays as a catalyst (32), or at room temperature with triphosgene (33). 

Diacids. The microbial generation of mahc, fumaric, and succinic acid essentially imphes Krebs cycle pathway engineering of biocatalytic organisms to overproduce oxaloacetate as the primary four-carbon diacid that subsequently undergoes reduction and dehydration processes (Scheme 2.9). The use of these four-carbon diacids as intermediate chemicals and the state of their desirable microbial production is briefly outlined. 

Succinic acid. Succinic add is also available via fermentation of glucose, and has the potential to become a large-scale industrial chemical in the future. However, there are only a few reports on dehydration reactions involving succinic acids in the literature, and most of these are concerned with esterification to produce dialkyl esters. The synthesis of various dialkyl esters was reported using metal exchanged montmorillonite clays (Na, Mn ", ... 

If the acyl chlorides are not available, use may be made of excess of acetic anhydride or acetyl chloride to dehydrate the acid. For example, succinic acid when refluxed with excess of acetic anhydride or acetyl chloride is converted completely to succinic anhydride ... 

The phase separation of reactants hindered attempts to carry out lipase-catalyzed synthesis of poly(butylene succinate) (PBS) from succinic acid and 1,4-butanediol via dehydration. Therefore, in order to obtain a monophasic reaction mixture, dimethyl succinate was used in place of succinic acid. [49] The reaction mixture remained monophasic during the reaction course, and after 21 h at 95 °C PBS with M of 38000 was obtained. 

The DTA curve for oxalic acid dihydraie. the only acid studied containing water of hydration, had dehydration peaks with A7 n values ofl 10.120, and 125 C, respectively. All other curve peaks for the organic acids were caused by fusion and decomposition reactions. For example, the second endothermic peak in the succinic acid curve was probably caused by dehydration reaction. 

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