Unsaturated Diacids

Maleic acid COOH(CH)2COOH and itaconic acid C3H4(COOH)2 have practically no action on aluminium at room temperature. In solutions of maleic acid at 5,15 and 30%, the decrease in thickness of 1100 is less than 10p,m per year, independent of the concentration. At higher temperatures, such as 100 °C or above, the dissolution rate significantly increases. 

Maleic acid can be stored and transported in aluminium equipment, which is also used for the fabrication of itaconic acid. 

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A cross-linked and crystalline copoly(ester—imide) containing an alkene function was made by reaction of an unsaturated diacid chloride containing a cychc imido group with ethylene glycol at low temperature (27). 

The diacids are characterized by two carboxyHc acid groups attached to a linear or branched hydrocarbon chain. AUphatic, linear dicarboxyhc acids of the general formula HOOC(CH2) COOH, and branched dicarboxyhc acids are the subject of this article. The more common aUphatic diacids (oxaUc, malonic, succinic, and adipic) as weU as the common unsaturated diacids (maleic acid, fumaric acid), the dimer acids (qv), and the aromatic diacids (phthaUc acids) are not discussed here (see Adipic acid Maleic anhydride, maleic acid, and fumaric acid Malonic acid and derivatives Oxalic acid Phthalic acid and OTHERBENZENE-POLYCARBOXYLIC ACIDS SucciNic ACID AND SUCCINIC ANHYDRIDE). The bihinctionahty of the diacids makes them versatile materials, ideally suited for a variety of condensation polymerization reactions. Several diacids are commercially important chemicals that are produced in multimillion kg quantities and find appHcation in a myriad of uses. 

Of the higher diacids, the ahcycHc, unsaturated Diacid 1550 (the Westvaco C-21 diacid) is significantly water soluble and is moderately irritating both dermaHy and ocularly. The corresponding dipotassium salt. Diacid H-240, is substantially mote irritating (127). 

Unsaturated polyesters are low-molar-mass polymers (1500-2500) obtained by the polyesterification of stoichiometric mixtures of diols and mixtures of saturated and unsaturated diacids or anhydrides (see Section 2.4.2.1). 

Decarboxylative condensations of this type are sometimes carried out in pyridine, which cannot form an imine intermediate, but has been shown to catalyze the decarboxylation of arylidene malonic acids.215 The decarboxylation occurs by concerted decomposition of the adduct of pyridine to the a, 3-unsaturated diacid. 

Nickel-catalyzed carbonylation of a-haloalkynes with carbon monoxide under phase-transfer conditions gave either allenic monoacids or unsaturated diacids.93 The carbonylation initially afforded monoacids, which reacted further to give diacids with high stereoselectivity (Eq. 4.52). 

Breukers S, 0pstad CL, Sliwka HR, and Partali V. 2009. Hydrophilic carotenoids Surface properties and aggregation behaviour of the potassium salt of the highly unsaturated diacid norbixin. Helvetica Chimica Acta 92(9) 1741-1747. 

Similarly, allenes [32] and alkynols [33] were used as starting materials and their carbonylation provides /3,y-unsaturated acids and unsaturated diacids, respectively. The specific reactivity of alkynols is explained by three formal steps during nickel catalysis (i) carbonylation of the triple bond leading to an acid containing an allylic alcohol moiety (ii) second carbonylation of the double bond to provide a hydroxydiacid and (iii) a dehydration step giving the corresponding unsaturated diacid (Scheme 2). 

The authors show that the phase transfer agent exerts a strong influence on the stereochemistry observed in the final product since -E-unsaturaled diacids are the major products in the presence of polyethylene glycol (PEG-400), whereas Z-isomers are obtained when quaternary ammonium salts are added [34]. 

Scheme 2 Formation of a /S,y-unsaturated diacid from an alkynol...

Complexes of other metals are also capable of catalyzing useful carbonylation reactions under phase transfer conditions. For example, certain palladium(o) catalysts, like Co2(C0)g, can catalyze the carbonylation of benzylic halides to carboxylic acids. When applied to vinylic dibromides, unsaturated diacids or diynes were obtained, using Pd(diphos)2[diphos l,2-bis(diphenylphosphino)ethane] as the metal catalyst, benzyltriethylammonium chloride as the phase transfer agent, and t-amyl alcohol or benzene as the organic phase(18),... 

Fumaric and itaconic acids are also used as the diacid component. Most reaction formulations involve a mixture of a saturated diacid (iso- and terephthalic, adipic) with the unsaturated diacid or anhydride in appropriate proportions to control the density of crosslinking (which depends on the carbon-carbon double-bond content of the prepolymer) for specific applications [Parker and Peffer, 1977 Selley, 1988], Propylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, and bisphenol A are also used in place of ethylene glycol as the diol component. Aromatic reactants are used in the formulation to improve the hardness, rigidity, and heat resistance of the crosslinked product. Halogenated reactants are used to impart flame resistance. 

Oxidative lactonization of unsaturated diacids (9, 265). Further study of this reaction indicates that it is general and can be controlled to result in cts-addition of two carboxylic oxygens to the double bond. Two experimental conditions are satisfactory (I) treatment of the diacid in CHClj or CII3CN with a large excess of Pb(0Ac)4 and (2) treatment of the tetra-n-butylammonium salt of the diacid in CH3CN with 6 15 equivalents of PbfOAc).,. Yields by the latter procedure are generally higher. 

Other preparations of 2-iminothiazolidin-4-ones which are discussed in the review by Brown139 utilize the reactions of thiourea with a-hydroxy acids,146 ethyl diazoacetate,73 glycidic esters,74,147 cinnamic acid,148 unsaturated diacids (fumaric, maleic, and citraconic) or their esters or imides,149-152 and propiolic esters.153,154 There has been considerable controversy in the literature surrounding the propiolic ester synthesis since many workers have proposed that the products are 1,3-thiazines (see Section IV, B, 1). The pertinent papers in this controversy have been summarized by Cain and Warrener.155 Nagase158 has recently settled the argument in favor of the 2-iminothiazolidin-4-... 

Compound 85 was dehydrogenated at 300° over palladium black under reduced pressure to a pyridine derivative 96 which was independently synthesized by the following route. Anisaldehyde (86) was treated with iodine monochloride in acetic acid to give the 3-iodo derivative 87. The Ullmann reaction of 87 in the presence of copper bronze afforded biphenyldialdehyde (88). The Knoevenagel condensation with malonic acid yielded the unsaturated diacid 91. The methyl ester (92) was also prepared alternatively by a condensation of 3-iodoanisaldehyde with malonic acid to give the iodo-cinnamic acid (89), followed by the Ullmann reaction of its methyl ester (90). The cinnamic diester was catalytically hydrogenated and reduced with lithium aluminium hydride to the diol 94. Reaction with phosphoryl chloride afforded an amorphous dichloro derivative (95) which was condensed with 2,6-lutidine in liquid ammonia in the presence of potassium amide to yield pyridine the derivative 96 in 27% yield (53). 

Elimination sometimes accompanied tosyloxylactonization then, the crude reaction mixture was treated with 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) and unsaturated lactones were obtained directly. A series of suitably constructed unsaturated diacids were produced with HTI bis-lactones, as the result of stereoselective ds-addition of the carboxy groups to the double bond, for example [7] ... 

Corey EJ, Gross AW (1980) Bislactonization of Unsaturated Diacids using Lead Tetraacetate. Tetrahedron Lett 21 1819... 

TABLE 7. Phase Behavior of Binary Mixtures of Saturated-unsaturated Diacid and Triacid TAGs. 

The catalytic pair Ni(CN)2/Bu4N Br readily catalyzes the biphasic carbonyla-tion of a-haloalkynes [144, 145] and allenyl halides [145]. The first reaction results in a mixture of allenic monoacids and unsaturated diacids, whereas allenyl halides transform to allenic acids with high regioselectivity. The carbonylation of gem-dibromocyclopropanes under PTC conditions is catalyzed by Ni" and Co" salts. The reaction gives the corresponding cyclopropanecarboxylic acids in fair yields [146]. 

The PTC reaction of phenylacetylene with CO in the presence of nickel cyanide affords atropic acid [151]. A similar reaction involving alkynols gives unsaturated diacids. The stereoselectivity of the reaction is sensitive to the nature of the quaternary ammonium salt (eq. (13)) [152]. 

Butane to Maleic Anhydride Process, Maleic anhydride is an unsaturated diacid that is used in the manufacture of several key products.The chemistry, applications, and process technology of MAN have been described in several comprehensive reviews. 

Catalyzed by Ni, the unsaturated diacid, HHH, next undergoes hydrogenation at the two double bonds formed previously in the Hofmann eliminations and gives rise to heptane dioic acid, which is an unbranched, open-chained diacid with the structure HOOC-CH2-CH2-CH2-CH2-CH2-COOH. 

The constitution of the unsaturated polyester resin used to make a gelcoat is obviously a prime factor in determining its weathering performance. Base polyesters (which are subsequently dissolved in the monomer) are made by reacting together saturated and unsaturated diacids and diols, and variation of these ingredients enables properties such as flexibility, heat distortion... 

Unsaturated polyester UP Unsaturated diacid and diol Polyaddition None Styrene... 

The materials in this group are linear copolyesters. One of the dicarboxylic acids is an aliphatic unsaturated diacid. The unsaturation is introduced into the polymer backbone for the purpose of subsequent crosslinking. Unsaturated polyester technology was developed for use in glass fiber laminates, thermosetting molding compositions, casting resins, and solventless lacquers. 

This section in a similar way as the previous one summarizes a number of studies on the adsorption saturated and unsaturated diacids to (oxy)(hydr)oxide minerals. The chemical speciation (in terms of the number of species in solution) becomes more complex for these compounds, which concomitantly enhances the possibilities of the diacids to form surface complexes of different stoichiometries in terms of bonding and proton balances. The diacids addressed are summarized in tables 3 (saturated diacids) and 4 (imsaturated diacids). The remainder of the section discusses in some detail published findings from ATR-FTIR spectroscopy. 

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