BISPHENOLS CONTAINING PENDANT CLICKABLE MALEIMIDE GROUP AND POLYMERS THEREFROM

Abstract

The patent discloses bisphenol monomers of formula I with pendant maleimide group connected via alkylene spacer and preparation thereof. Also, it discloses polymers based on bisphenol monomers containing pendant clickable maleimide group. Further, it provides a process for the preparation of polymers possessing pendant clickable maleimide groups based on bisphenols containing pendant maleimide group. Formula (I) wherein, x is an integer selected from 0 to 10.

##STR00001##

Claims

1. A compound of Formula (I) ##STR00011## wherein, x is an integer selected from 0 to 10.

2. A process for the synthesis of compound of Formula I comprising the steps of: a. stirring the reaction mixture comprising alkylenediamine and phenolphthalein in the molar ratio ranging between 10:1 to 20:1 for period in the range of 45 to 55 h at temperature in the range of 100 to 150° C. to afford phenolphthalein N-(aminoalkyl)lactam; and b. stirring the reaction mixture comprising phenolphthalein N-(aminoalkyl)lactam as obtained in step (a), maleic anhydride and glacial acetic acid for period in the range of 10 to 15 h at temperature in the range of 100 to 120° C. to afford compound of Formula I.

3. The process as claimed in claim 2, wherein the compound of Formula (I) is phenolphthalein N-(maleimidoethyl)lactam.

4. The compound as claimed in claim 1, wherein said compound is useful for the preparation of polymers.

5. The compound as claimed in claim 4, wherein the polymers are selected from polycarbonates, polyether sulfones, polyetherketones, epoxy resins or polyesters of formula II, ##STR00012## wherein; x is selected from 0 to 10 and Ar is selected from ##STR00013## or mixture thereof.

6. A process for the synthesis of polyesters of formula II as claimed in claim 5, wherein the process comprises the steps of: a) adding a solution of isophthaloyl chloride in dichloromethane to a phenolphthalein N-(maleimidoalkyl)lactam in dichloromethane in the presence of triethylamine and maintaining the reaction temperature at 0 to 10° C.; and b) stirring the reaction mixture of step (a) for period in the range of 20 to 30 min to get desired aromatic polyester.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 represents .sup.1H-NMR spectrum (in DMSO d.sub.6) of phenolphthalein N-(3-maleimidoethyl)lactam.

[0028] FIG. 2 represents .sup.1H-NMR spectrum (in CDCl.sub.3) of polyester obtained by polycondensation of phenolphthalein N-(3-maleimidoethyl)lactam and isophthaloyl chloride.

[0029] Scheme 1 represents a process for the preparation of bisphenol monomers containing pendant maleimide groups.

[0030] Scheme 2 represents a process for the preparation of polyesters based on bisphenols with pendant maleimide group.

DETAILED DESCRIPTION OF THE INVENTION

[0031] Present invention provides bisphenol monomers of formula (I) containing pendant maleimide group which is connected via alkylene spacer.

##STR00008##

wherein, x is an integer selected from 0 to 10.

[0032] In another aspect, compound of formula (I) is phenolphthalein N-(maleimidoethyl)lactam.

[0033] The present invention provides a simple and cost efficient process for the preparation of bisphenol monomer containing pendant maleimide group using phenolphthalein as a commercially available starting material employing simple organic transformations. In another aspect, the present invention provides polymers based on bisphenol monomers containing pendant clickable maleimide group.

[0034] The present invention provides a process for the preparation of bisphenol monomers containing pendant maleimide groups and the said process comprising the steps of: [0035] a) stirring the reaction mixture comprising alkylenediamine and phenolphthalein in the molar ratio ranging between 10:1 to 20:1 for period in the range of 45 to 55 h at temperature in the range of 100 to 150° C. to afford phenolphthalein N-(aminoalkyl)lactam; and [0036] b) stirring the reaction mixture comprising phenolphthalein N-(aminoalkyl)lactam as obtained in step (a), maleic anhydride and glacial acetic acid for period in the range of 10 to 15 h at temperature in the range of 100 to 120° C. to afford compound of formula I.

[0037] The process for the preparation of bisphenol monomers containing pendant maleimide groups as described above is shown in Scheme 1.

[0038] The present invention provides compounds of formula (I) with thermally cross linkable maleimide group for synthesis of polymers selected from, but not limited to polyesters, polycarbonates, polyether sulfones, polyetherketones, epoxy resins, and the like.

[0039] The present invention provides polyester of formula (II) based on bisphenol monomer with pendant maleimide group of formula (I).

##STR00009##

wherein, x is selected from 0 to 10 and Ar is selected from the following:

##STR00010##

[0040] The present invention provides a process for the preparation of polyesters starting from bisphenols with pendant maleimide group as disclosed herein comprising the steps of: [0041] a) adding a solution of isophthaloyl chloride in dichloromethane to a solution phenolphthalein N-(maleimidoalkyl)lactam in dichloromethane in the presence of triethylamine and maintaining the reaction temperature at 0° C.; and [0042] b) stirring the reaction mixture of step (a) for 30 min at 0° C. and for 1 h at 25° C. to get desired aromatic polyester.

[0043] The process for the preparation of polyesters based on bisphenols with pendant maleimide group is shown in scheme 2.

[0044] In a preferred aspect, these polymers of present invention containing pendant maleimide groups are capable of undergoing thiol-ene reaction and Diels-Alder reaction to form graft copolymers.

[0045] In another preferred aspect, these polymers of present invention containing pendant maleimide groups can be crosslinked thermally or by using bis-furan reagents into thermosetting resins.

EXAMPLES

[0046] The following examples are given by way of illustration and therefore should not ne construed to limit the scope of the invention.

Example: 1

A) Synthesis of Phenolphthalein N-(3-aminoethyl)lactam

[0047] Into a 500 mL three-necked round-bottom flask equipped with a mechanical stirrer, a gas inlet and a reflux condenser were placed phenolphthalein (25 g, 78.23 mmol) and ethylenediamine (100 mL). The reaction mixture was stirred at 120° C. for 48 h. The excess of ethylenediamine was removed by distillation. The resulting residue was slowly poured into acidified cold water and the precipitated solid was separated by filtration. The obtained solid was dissolved in hot water and the solution was treated with 10% aqueous potassium hydroxide solution while hot. The pH of solution was adjusted to 8 and the separated solid was collected by filtration. The product was purified by recrystallization from a mixture of ethanol and water (1:1, v/v). Yield: 22.6 g (80%). M.P: 260° C. IR (cm.sup.−1): 1658 (C═O). .sup.1H NMR (400 MHz, DMSO-d.sub.6) δ/ppm 7.65 (d, 1H), 7.55-7.44 (m, 1H), 7.44-7.37 (m, 1H), 7.34 (d, 1H), 6.91 (d, 4H, Ar—H meta to Phenolic OH), 6.69 (d, 4H, Ar—H ortho to Phenolic OH), 3.34-3.08 (m, 6H, —NH.sub.2, CH.sub.2, Phenolic OH), 1.92-1.74 (m, 2H).

B) Synthesis of Phenolphthalein N-(3-maleimidoethyl)lactam

[0048] Into a 500 mL two-necked round-bottom flask equipped with a mechanical stirrer, a gas inlet and a reflux condenser were placed phenolphthalein N-(3-aminoethyl)lactam (10 g, 27.76 mmol), maleic anhydride (5.45 g, 55.53 mmol) and glacial acetic acid (100 mL). The reaction mixture was stirred at 120° C. for 12 h. The reaction mixture was cooled to 25° C. and slowly poured into an ice cold-water. The solid product was collected by filtration. The product was dissolved in ethyl acetate and the solution was washed with water (3×100 mL). The ethyl acetate solution was dried over anhydrous sodium sulphate, filtered and ethyl acetate was removed by evaporation under reduced pressure. The crude product was purified by column chromatography using pet ether: ethyl acetate (30:70, v/v) as an eluent to afford pure phenolphthalein N-(3-maleimidoethyl)lactam. (FIG. 1)

[0049] Yield: 6.8 g (56%), MP: 288° C., IR (cm.sup.−1): 1700 (C═O). .sup.1H NMR (500 MHz, DMSO-d.sub.6) δ/ppm 9.58 (br. s., 2H Phenolic OH), 7.69 (d, 1H), 7.59-7.51 (m, 1H), 7.49-7.41 (m, 1H), 7.37 (d, 1H), 6.93 (d, 4H, Ar—H meta to Phenolic OH), 6.81 (s, 2H, Maleimide), 6.72 (d, 4H, Ar—H ortho to Phenolic OH), 3.56 (t, 2H), 3.01 (t, 2H).

Example: 2

Synthesis of Polyester by Low Temperature Solution Polycondensation of Phenolphthalein N-(3-maleimidoethyl)lactam and Isophthaloyl Chloride

[0050] Into a 100 mL three-necked round bottom flask equipped with a magnetic stirrer, a nitrogen gas inlet and a calcium chloride guard tube were placed of phenolphthalein N-(3-maleimidoethyl)lactam (0.50 g, 1.13 mmol), dichloromethane (7 mL), and triethylamine (0.45 mL, 3.24 mmol), and the solution was cooled to 0° C. To the reaction mixture, the solution of isophthaloyl chloride (0.23 g, 1.135 mmol) in dichloromethane (10 mL) was added drop wise over a period of 20 min. The reaction mixture was stirred at 0° C. for 30 min and at 25° C. for 1 h. The viscous reaction mixture was diluted with dichloromethane (5 mL), and the solution was poured slowly into n-hexane (50 mL) to precipitate the polymer. The precipitated polymer was isolated by filtration, washed with water (5×100 mL) followed by washing with methanol (2×50 mL) and dried at 50° C. under reduced pressure for 20 h. (FIG. 2)

Advantages of the Invention

[0051] Inexpensive and easily available raw materials used [0052] Simple and cost-effective process [0053] Bisphenol monomers containing pendant maleimide group connected via alkylene spacer [0054] Polymers containing pendant maleimide groups are capable of undergoing thiol-ene reaction and Diels-Alder reaction to form graft copolymers [0055] Polymers containing pendant maleimide groups can be crosslinked thermally or by using bis-furan reagents into thermosetting resins.