N- maleimides

Difunctional vinvl ether/difunctional N-maleimide. Up until this point, our results have centered on the reactivity of monofunctional maleimide divinyl ether mixtures. From Kloosterboer s26 work for acrylate polymerization, it is known that the rate of polymerization of a free-radical process is increased dramatically as the functionality of the acrylate is increased. In order to enhance the polymerization rates of maleimide divinyl ether systems, it was decided to synthesize difimctional maleimides for copolymerization with difunctional vinyl ethers. The results in Table V indicate that the photoinitiated TTDBM [bismaleimide made from maleic anhydride and 4,7,10-... 

N-MaIeimide-c -styrene Single Tg FTIR II had 45 wt% N-maleimide Vermeesch and Groeninckz (1995)... 

Early EPR studies of normal human erythrocyte membranes labelled with N-( 1 oxyl-2,2,6,6- tetramethyl 4-piperidinyl ) maleimide ( see Figure 1. b ) which is a derivative of NEM indicated that 75 % of the total labelled sites belong to the spect rin-actin complex [lO], Membranes were incubated with N-Maleimide at 4 C. It was also indicated that the differences between the results of [4] and [lO] may be due to the difference of the molecules and different incubation temperatures used. 

Thermal cross-linking of phenol polymers was also achieved by copolymerization of two different functional phenols. A copolymer of 4-hydroxyphenyl-N-maleimide (57, Scheme 12) and a furanosyl derivative (N-(4-hydroxy-phenyl)-2-furamide (64), Scheme 13) was subjected to irreversible cross-linking by thermally induced [4 + 2] cycloaddition (Diels-Alder cycloaddition). The copolymerization behavior of these two phenols was studied by following the monomer concentrations by HPLC, the increasing molecular weight by GPC, and the polymer composition by MALDI-TOF mass spectroscopy. It was found that the more electron rich and sterically less demand-... 

Also obtained (poor yield) from SMI in refluxing toluene (at 110°) or in o-dichlorobenzene (at 180°) for 3 h under nitrogen (2-5%, yields respectively). The reaction carried out in the presence of N-maleimide in refluxing toluene in the same conditions gave a 3% yield [1421]. 

Sharl996 Sharma, S.K., Wu, A.D. and Chandramouli, N., Maleimide-Assisted On-Resin Macrocyclization, Tetrahedron Lett., 37 (1996) 5665-5668. 

Over the years many attempts have been made to produce commercial acrylic polymers with a higher softening point than PMMA. The usual approach was to copolymerise MMA with a second monomer such as maleic anhydride or an N-substituted maleimide which gave homopolymers with a higher Tg than PMMA. In this way copolymers with Vicat softening points as high as 135°C could be obtained. 

The original compound, maleimide (2,5-dioxo-A -pyrroline), is synthesized by the cyclo-condensation of ammonia and maleic acid. Similarly, primary amine is added to maleic anhydride, followed by cyclocondensation, to form N-substituted maleimide (Fig. 2). This reaction is applied to the preparation of bis-maleimides (BMl) [1]. At first, BMI was used as a crosslinking agent for natural rubber (NR). An o-dichlorobenzene solution of NR was crosslinked by BMI at I08-150°C in the presence of peroxides. The radicals generated from peroxides react with the double bonds of both BMI and NR [ 1 ]. 

BMI also reacts with dienes to form Diels-Alder adducts [12]. When BMI reacts with a a,(n-biscyclopentadienyl compound or other bis-diene resin, the bis-maleimide chain is extended by the Diels-Alder reaction. Bis-maleimide, chain extended with bis-diene, is not used in adhesives. However, as the Diels-Alder reaction is reversible, there may be a possibility of recyclability of the cured resin by depolymerization of the backbone (Fig. 6). 

Pyridinium p-toluenesulfonylmethylide 91 has been used as a formyl anion equivalent for conjugate addition to N-substituted maleimides to give the enol ethers 92, which were readily deprotected to give the aldehydes 93 (80TL705). 

Phosphorus containing poly(maleimide-amines) were synthesized from N,N -bisdichloromaleimido-3,3 -diphenyl alkylphosphine oxides and aromatic diamines or piperazine [144]. The polymers prepared from piperazine are soluble in DMF, DM AC, DMSO, etc., but have poor thermal stability and flame retardancy. 

Values of termination constants for sterically hindered monomers may be several orders of magnitude lower than those for S and (methacrylates). Such monomers include various ra-substituted methacrylates, itaconates, fumarates, and N-substituted itaconimides and maleimides. Values of kt for these monomers have been reported to lie in the range IQ-1Q5 NT s 1 depending on the particular... 

Various o-quinodimethanes, generated in situ from o-alkenylbenzyltributyl-stannane precursors, have been used to synthesize functionalized polycycles by Diels Alder reaction with maleic anhydride, methylacrylate, dimethylfumarate and N-phenyl maleimide in the presence of electrophiles [37] (Scheme 2.16). 

Engberts [3e, 9] has extensively investigated the Diels Alder reaction in aqueous medium. Recently Engberts and colleagues reported [9c] a kinetic study of a Diels Alder reaction of N-alkyl maleimides with cyclopentadiene, 2,3-dimethyl-1,3-butadiene and 1,3-cyclohexadiene in different solvents. The reaction rates of the cycloadditions with the open-chain diene relative to w-hexane are reported in Table 6.3. The aqueous medium greatly accelerates the Diels Alder reaction and the acceleration increases as the hydrophobic character of the alkyl group of the dienophile increases. These and other kinetic data [3e, 9], along with the observation that the intramolecular Diels-Alder reaction is also accelerated in... 

Fig. 25 ABA-type block copolymer formed by reaction of maleimide-functionalised PEG with cysteine-flanked [(AG)3EG]n p-sheet element. Reproduced with permission from Smeenk et al. [69]. Copyright Wiley-VCH... 

Figure 6-7. N-Cyclohexyl maleimide, 2,5-diaminonorbornylene, isophorone diamine.

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