Maleamic acids

Maleic anhydride condenses with 2-aminothiazole-4-carboxylic acid giving the raaleimide 107 (269) another report claims, however, that the reaction of 2-amino-4-methylthiazole with this anhydride gives the N-substituted maleamic acid (108) (Scheme 73) (270). 

Amidation. Reaction of maleic anhydride or its isomeric acids with ammonia [7664-41-7] (qv), primary amines (qv), and secondary amines produces mono- or diamides. The monoamide derivative from the reaction of ammonia and maleic anhydride is called maleamic acid [557-24-4] (8). Another monoamide derivative formed from the reaction of aniline [62-53-3] and maleic anhydride is maleanilic acid [555-59-9] (9). 

Z-Maleamic acid (cis-maleic acid monoamide) [557-24-4] M 115.1, m 158-161 , 172-173 (dec), pKes, -2.65. Crystd from EtOH. IRRITANT. 

Photosensitive functions are in many cases also heat sensitive, so the preparation of photosensitive polyimides needs smooth conditions for the condensations and imidization reactions. Some chemical reactants, which can be used for polyamide preparation, have been patented for the synthesis of polyimides and polyimide precursors. For example, chemical imidization takes place at room temperature by using phosphonic derivative of a thiabenzothiazoline.102 A mixture of N -hydroxybenzotriazole and dicyclohexylcarbodiimide allows the room temperature condensation of diacid di(photosensitive) ester with a diamine.103 Dimethyl-2-chloro-imidazolinium chloride (Fig. 5.25) has been patented for the cyclization of a maleamic acid in toluene at 90°C.104 The chemistry of imidazolide has been recently investigated for the synthesis of polyimide precursor.105 As shown in Fig. 5.26, a secondary amine reacts with a dianhydride giving meta- and para-diamide diacid. The carbonyldiimidazole... 

Figure 5.25 Cyclization of maleamic acid with imidazolinium salt.

Maleamic acid, cyclization of, 293 Maleic anhydride, 59 Maleimido azine, 307 Manganese diacetate catalysts, 71 Mark-Houwink-Sakurada equation, 57 Material safety data sheets (MSDSs), 246 Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS), 385, 388 McGrath, J. E., 327 MDI isomers, 210 MDIs. See Methylene diphenyl diisocyanates (MDIs)... 

According to the processes mentioned above, MA was reacted with a primary or secondary amine, as shown in Scheme 5. Amidation usually occures in 1 h at a temperature below 100°C either in suitable anhydrous solvents or in the absence of solvents. Then the resulting maleamic acid can be esterified with or... 

FIGURE 13.8 Co-agents used. From left to right m-phenylenedimaleitnide (PDMI), m-phenylenedi(maleamic acid) (PDMA), l,6-hexamethylenedi(maleamic acid) (HMDMA), and trimethylolpropane trimethacrylate (TMPTMA). 

Remove excess crosslinker by centrifugal dialysis or gel filtration using a molecular weight exclusion of 5,000. This procedure should be done quickly due to the labile nature of the maleimide group in aqueous solution, which will hydrolyze to a ring-open maleamic acid that is ineffective at coupling to thiols. 

Figure 19.17 A maleimide group may hydrolyze in aqueous solution to an open maleamic acid form that is unreactive with sulfhydryls.

Malaysia, aromatics market in, 24 276-277 Malcolm Baldrige National Quality Award (MBNQA), 22 168, 170, 173 MALDI spectra, 25 659 Maleamic acid, 25 486 Maleanilic acid, 25 487 Maleate, in silicone network preparation, 22 566... 

Allvl Maleimide—Allyl maleamic acid (50 gj 0.3326 mol) was melted at 125°C, poured into a 100 mL round bottom flask and distilled under reduced pressure to yield 17.8 g (39% of theory) of a colorless liquid which crystallized in the receiving flask as a white solid, m.p. 41-44°C (Lit. m.p. 42-44°C) (12). 

N-(3-ethvnvlphenvl)maleimide—N-(3-ethynylphenyl)maleamic acid (21.5 g 0.100 mol), anhydrous sodium acetate (6.0 g 0.0731 mol), and 175 mL of acetic anhydride (1.86 mol) were stirred together and heated at 50°C for 3 hr. The reaction mixture was cooled to room temperature and filtered. The filtrate was precipitated in an ice-water mixture to yield an impure product. This product was dissolved in hot ethanol and recrystallized by addition of cold water to yield 5.3 g (27% of theory) of a fine yellow powder, m.p. 130-131°C. 

Crosslinking of amine- or hydroxy-terminated PAMAM dendrimers using cyclic anhydride - amine or cyclic anhydride - hydroxy addition reactions was employed for preparation of crosslinked thin films of very low permeability [73], Polyanhydrides, such as maleic anhydride-methyl vinyl ether copolymers, were used as crosslinking components. In the case of amine-terminated PAMAM, crosslinking and chemical stability were further increased by imidization of the maleamic acid groups retro-Michael eliminations were followed by Michael additions to further crosslink the film. 

Comparative data for the hydrolysis of substituted maleamic acids... 

AB maleimide benzocyclobutene monomers and polymers have also been actively studied and developed by researchers at the Dow Chemical Co. The first AB maleimide type benzocyclobutene monomer prepared and polymerized by Kirchhoff was the benzocyclobutenyl maleamic acid 106 [6]. The detailed synthesis of 106 is shown in Fig 44. 

The first polymer prepared was from the ammonium salt of the maleamic acid 106. Acid 106 was reacted with ammonium hydroxide to form the water soluble ammonium maleamate salt which was in turn cast as a film upon glass [6]. Evaporation of the water followed by thermal curing of the salt at 175 °C provided a pale yellow coating which adhered quite well to the glass and was not affected by a variety of organic solvents. It also showed thermal stability up to... 

It is well documented that the isoimide is the kinetically favoured product and that isomerization yields the thermodynamically stable imide when sodium acetate is used as the catalyst. High catalyst concentrations provide maleimides with low isoimide impurity. The mechanism by which the chemical imidization is thought to occur is shown in Fig. 3. The first step in the dehydration reaction may be formation of the acetic acid-maleamic acid mixed anhydride. This species could lose acetic acid in one of the two ways. Path A involves participation by the neighboring amide carbonyl oxygen to eject acetate ion with simultaneous or subsequent loss of proton on nitrogen to form the isoimide. Path B involves loss of acetate ion assisted by the attack of nitrogen with simultaneous or subsequent loss of the proton on nitrogen to form the imide. If the cyclodehydration is run in acetic anhydride in the absence of the base catalyst, isoimide is the main reaction product. 

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