ASYMMETRICAL METHYLENE BIS IMIDES AND THEIR PREPARATION

The invention discloses asymmetrical methylene bisimides, such as bis maleimides and methylene bis phthalimides, their preparation and their use for the preparation of resins.

BACKGROUND OF THE INVENTION

There is an increasing demand of resins with application properties meeting the demand of high-end applications.

JP S 6193159 A discloses the use of bis maleimide derivatives, which are used for the preparation of resins.

EP 0544 266 A1 discloses a method for preparation of symmetrical methylene bis maleimides.

There was a need for resins which show good application properties, such as lower viscosity and better solvent solubility combined with similar or lower reactivity as compared to known methylene bis maleimides resins.

Reduced viscosity results in lower process temperatures and thus lower energy consumption, which is economically and environmentally advantageous. Reduced viscosity, improved solubility in common solvents and/or low reactivity enable easier processing.

Surprisingly, this need was met by the asymmetrical methylene bis imides of the instant invention. ABBREVIATIONS alkyl linear or branched alkyl asym asymmetric eq equivalents; if not otherwise specified, the equivalents are molar equivalents

Ex Example sym symmetric

SUMMARY OF THE INVENTION

Subject of the invention is a method for the preparation of a compound of formula (I) by a reaction (I) of a compound of formula (II) with maleic anhydride, citraconic anhydride, nadic anhydride, methyl-nadic-anhydride or 1,2,3,6-tetrahydrophthalic anhydride; wherein

* and ** each denote a covalent bond to the respective C atom denoted with * and ** of a residue (A);

(A) is either a residue of formula (M), a residue of formula (P), a residue of formula (Q), a residue of formula (O) or residue of formula (T); the residues R2L, R3L, R6L, R2R, R3R and R6R are identical or different and independently from each other selected from the group consisting of H, C1-4 alkyl and Cl; with the proviso that within at least one of the three pairs:

1. R2L and R2R

2. R3L and R3R

3. R6L and R6R are different residues.

DETAILED DESCRIPTION OF THE INVENTION

Preferably, R2, R3 and R6 are identical or different and independently from each other selected from the group consisting of H, methyl, ethyl, n-propyl, iso-propyl, and Cl; more preferably, R2, R3 and R6 are identical or different and independently from each other selected from the group consisting of H, methyl, ethyl, iso-propyl, and Cl.

In a further preferred embodiment, R2, and R6 are identical or different and independently from each other selected from the group consisting of H, methyl, ethyl, n-propyl, iso propyl, and Cl, while R3 is independently selected from the group consisting of H, methyl, ethyl, n-propyl and iso-propyl; more preferably, R2 and R6 are identical or different and independently from each other selected from the group consisting of H, methyl, ethyl, iso-propyl, and Cl, while R3 is independently selected from the group consisting of H, methyl, ethyl and iso-propyl.

Preferably, the compound of formula (II) is reacted with maleic anhydride, citraconic anhydride, nadic anhydride or methyl-nadic-anhydride and (A) is a residue of formula (M), (Q), (O) or (T). Most preferably, the compound of formula (II) is reacted with maleic anhydride and (A) is a residue of formula (M). Preferred embodiments of the compound of formula (I) are selected from the group consisting of compound of formula (Ilia; BMIDEAMEA), compound of formula (Illb; BMIDIPADEA), compound of formula (IIIc; BMIDIPAMEA), compound of formula (Hid; BMIMIPADEA), compound of formula (Hie; BMIMIPADIPA), compound of formula (Illf; BMIMIPAMEA), compound of formula (Illg; BMICDEAMEA), compound of formula (Illh; BMICDEAMIPA), compound of formula (Illi; BMICDEADIPA) and compound of formula (Illj; BMICDEADEA).

More preferred embodiments of the compound of formula (I) are selected from the group consisting of compound of formula (Ilia; BMIDEAMEA), compound of formula (Illb; BMIDIPADEA), compound of formula (IIIc; BMIDIPAMEA), compound of formula (Hid; BMIMIPADEA), compound of formula (Hie; BMIMIPADIPA) and compound of formula (Illf; BMIMIP AME A) .

Preferably, the molar amount of maleic anhydride, citraconic anhydride, nadic anhydride, methyl-nadic-anhydride or 1,2,3,6-tetrahydrophthalic anhydride is from 2 to 4 fold, more preferably from 2 to 3 fold, even more preferably from 2 to 2.5 fold, of the molar amount of compound of formula (II).

Reaction (I) can be done in the presence of a catalyst (I); preferably, catalyst (I) is p-toluene sulfuric acid or p-toluene sulfuric acid monohydrate.

Preferably, the molar amount of catalyst (I) is from 0.1 to 1 fold, more preferably from 0.2 to 0.9 fold, even more preferably from 0.3 to 0.75 fold, of the molar amount of compound of formula (II).

Reaction (I) can be done in a solvent (I). Preferably, solvent (I) is a non-polar solvent that is capable of forming an azeotrope with water, preferably a positive azeotrope. Solvents are generally considered to be non-polar, if they have a dielectric constant of 15 or less. A positive azeotrope is a mixture of solvents which exhibits a boiling point that is lower than the boiling point of any of its constituents. More preferably, solvent (I) is toluene, a xylene isomer or a mixture of any of the aforementioned.

Preferably, the molar amount of solvent (I) is from 5 to 50 fold, more preferably from 10 to 30 fold, of the molar amount of compound of formula (II).

Preferably, reaction (I) is done at a reaction temperature of from 50 to 200 °C, more preferably of from 75 to 175 °C, even more preferably of from 100 to 175 °C, especially of from 120 to 160 °C.

Preferably, the reaction time of reaction (I) is from 1 to 12 h, more preferably of from 2.5 to 10 h, even more preferably of from 3 to 8 h.

Reaction (I) can be done under ambient pressure or under elevated pressure. Elevated pressure is for example applied when reaction (I) is done in a solvent (I) and the chosen temperature is above the boiling point of solvent (I).

After reaction (I), compound of formula (I) can be isolated according to standard methods which are known to the skilled person, such as removal of any solvent (I) that was used, preferably by distillation; adjusting the pH to an alkaline pH by addition of a base, preferably the base is sodium hydroxide, more preferably an aqueous solution of sodium hydroxide; separation of any aqueous phase from an organic phase; washing of an organic phase with water; removal of any solvent from an organic phase, preferably by distillation.

Preferably, a compound of formula (II) is prepared by a reaction (II) of compound of formula (IVa; AML) and compound of formula (IVb; AMR) with formaldehyde;

wherein

R2L, R3L, R6L, R2R, R3R and R6R are as defined herein, also with all their embodiments.

In one embodiment, a compound of formula (II), which is prepared by reaction (II), is obtained as a mixture (I). Mixture (I) is a mixture of compound of formula (II) with compound of formula (Va; BISL) and compound of formula (Vb; BISR); wherein R2L, R3L, R6L, R2R, R3R and R6R are as defined herein, also with all their embodiments.

Preferred embodiments of compound of formula (Va; BISL) and compound of formula (Vb; BISR) are selected from the group consisting of compound of formula (Via; BISDEA), compound of formula (VIb; BISDIPA), compound of formula (Vic; BISMIPA), compound of formula (VId; BISMEA) and compound of formula (Vie; BISCDEA).

More preferred embodiments of compound of formula (Va; BISL) and compound of formula (Vb; BISR) are selected from the group consisting of compound of formula (Via; BISDEA), compound of formula (VIb; BISDIPA), compound of formula (Vic; BISMIPA) and compound of formula (VId; BISMEA). Reaction (II) is a condensation of compound of formula (IVa) and compound of formula (IVb) with formaldehyde.

Compound of formula (Va; BISL) is symmetrically substituted and is obtained by reaction

(III) of 1 eq formaldehyde with 2 eq of compound of formula (IVa), reaction (III) occurs as a side reaction in reaction (II).

Compound of formula (Vb; BISR) is symmetrically substituted and is obtained by reaction

(IV) of 1 eq formaldehyde with 2 eq of compound of formula (IVb; AMR), reaction (IV) occurs as a side reaction in reaction (II).

In one embodiment, compound of formula (II) is used for and in reaction (I) in form of mixture (I).

Preferably, mixture (I) comprises compound of formula (II) in an amount of at least 30 wt%, at least 40 wt%, at least 50 wt%, at least 60 wt%, at least 70 wt% or at least 80 wt%, more preferably in an amount of at least at least 40 wt% or at least 50 wt%, most preferably in an amount of at least at least 40 wt%.

When compound of formula (II) is used for reaction (I) in form of mixture (I), then compound of formula (I) is obtained from reaction (I) in form of a mixture (II). Mixture (II) is a mixture of compound of formula (I) with compound of formula (Vila; BMIL) and compound of formula (Vllb; BMIR); Applicant: Arxada AG Title: ASYMMETRICAL METHYLENE BIS IMIDES AND THEIR PREPARATION Our ref.: ARX24751PCT Date: April 6, 2022 with *, **, R2L, R3L, R6L, R2R, R3R and R6R are as defined herein, also with all their embodiments. Preferred embodiments of compound of formula (VIIa; BMIL) and compound of formula 5 (VIIb; BMIR) are selected from the group consisting of compound of formula (VIIIa; BMIDEA), compound of formula (VIIIb; BMIDIPA), compound of formula (VIIIc; BMIMIPA), compound of formula (VIIId; BMIMEA) and compound of formula (VIIIe; BMICDEA). 10 15

More preferred embodiments of compound of formula (Vila; BMIL) and compound of formula (Vllb; BMIR) are selected from the group consisting of compound of formula (Villa; BMIDEA), compound of formula (VUIb; BMIDIPA), compound of formula (VIIIc; BMIMIPA) and compound of formula (VUId; BMIMEA).

Preferably, mixture (II) comprises compound of formula (I) in an amount of at least 20 wt%, at least 30 wt%, at least 40 wt%, at least 50 wt%, at least 60 wt% or at least 70 wt%, more preferably in an amount of at least at least 30 wt% or at least 40 wt%, most preferably in an amount of at least 30 wt%.

In a further embodiment, compound of formula (II) is used for and in reaction (I) in essentially pure form, i.e., it comprises compound of formula (Va; BISL) and compound of formula (Vb; BISR) in a collective amount of less than 30 wt%, less than 20 wt%, less than 10 wt% or less than 5 wt%.

The molar ratio of compound of formula (IVa) to compound of formula (IVb) may vary in a wide range; preferably, the molar amounts of compound of formula (IVa) and compound of formula (IVb) are comparable. Thus, preferably the molar ratio of compound of formula (IVa) to compound of formula (IVb) is from 4:1 to 1:4, more preferably from 2:1 to 1:2, even more preferably from 1.5:1 to 1:1.5, especially from 1.3:1 to 1:1.3. The choice of compound of formula (IVa) and compound of formula (IVb) in reaction (II) determines what specific mixture (I) is obtained from reaction (II); and the choice of mixture (I) in reaction (I) determines, what specific mixture (II) is obtained from reaction (I).

Table 1 shows preferred combinations of compound of formula (IVa; AML) and compound of formula (IVb; AMR) and the resulting compounds in mixture (I) obtained from reaction (II) and mixture (II) obtained from reaction (I).

More preferred combinations of compound of formula (IVa; AML) and compound of formula (IVb; AMR) according to Table 1 do not include CDEA (Xe).

The formaldehyde may be in the form of formalin solution, paraformaldehyde or trioxane or other well-known forms of free or combined formaldehyde, that form formaldehyde.

Preferably, the formaldehyde is used in the form of an aqueous solution.

More preferably, the formaldehyde is used in the form of an aqueous solution with 20 to 40 wt%, more preferably with 30 to 40 wt% of formaldehyde.

Preferably, the molar amount of formaldehyde is from 0.5 to 0.7 fold, more preferably from 0.5 to 0.6 fold, even more preferably from 0.5 to 0.55 fold, of the combined molar amount of compound of formula (IVa) and compound of formula (IVb).

Preferably, reaction (II) is done in acidic medium.

Preferably, reaction (II) is done in the presence of a catalyst (II); preferably, catalyst (II) is sulfuric acid.

Preferably, the molar amount of catalyst (II) is from 0.8 to 1 fold, more preferably from 0.85 to 1 fold, even more preferably from 0.85 to 0.95 fold, of the combined molar amount of compound of formula (IVa) and compound of formula (IVb).

Reaction (II) can be done in a solvent (II); preferably, solvent (II) is isopropanol.

Preferably, the molar amount of solvent (II) is from 1 to 50 fold, more preferably from 1.5 to 30 fold, even more preferably from 1.5 to 15 fold, especially from 1.5 to 10 fold, more especially from 1.5 to 7.5 fold, even more especially from 1.5 to 5 fold, of the combined molar amount of compound of formula (IVa) and compound of formula (IVb).

Preferably, reaction (II) is done at a reaction temperature of from 40 to 200 °C, more preferably of from 50 to 175 °C, even more preferably of from 50 to 150 °C, especially of from 50 to 125 °C, more especially of from 50 to 100 °C, even more especially of from 50 to 75 °C.

Preferably, the reaction time of reaction (II) is from 1 to 12 h, more preferably of from 2.5 to 10 h, even more preferably of from 4 to 8 h.

Reaction (II) can be done under ambient pressure or under elevated pressure. Elevated pressure is for example applied when reaction (II) is done in a solvent (II) and the chosen temperature is above the boiling point of solvent (II).

After reaction (II), compound of formula (II) can be isolated according to standard method which are known to the skilled person, such as removal of any solvent (I) that was used, preferably by distillation; adjusting the pH to an alkaline pH by addition of a base, preferably the base is sodium hydroxide, more preferably an aqueous solution of sodium hydroxide; separation of any aqueous phase from an organic phase; washing of an organic phase with water; removal of any solvent from an organic phase, preferably by distillation.

Preferred embodiments of compound of formula (II) are selected from the group consisting of compound of formula (IXa; BISDEAMEA), compound of formula (IXb; BISDIPADEA), compound of formula (IXc; BISDIPAMEA), compound of formula (IXd; BISMIPADEA), compound of formula (IXe; BISMIPADIPA), compound of formula (IXf; BISMIPAMEA), compound of formula (IXg; BISCDEAMEA), compound of formula (IXh; BISCDEAMIPA), compound of formula (IXi; BISCDEADIPA) and compound of formula (IXj; BISCDEADEA).

More preferred embodiments of compound of formula (II) are selected from the group consisting of compound of formula (IXa; BISDEAMEA), compound of formula (IXb; BISDIPADEA), compound of formula (IXc; BISDIPAMEA), compound of formula

(IXd; BISMIPADEA), compound of formula (IXe; BISMIPADIPA) and compound of formula (IXf; BISMIPAMEA).

Preferred embodiments of compound of formula (IVa) and compound of formula (IVb) are selected from the group consisting of compound of formula (Xa; MEA), compound of formula (Xb; DEA), compound of formula (Xc; DIP A), compound of formula (Xd; MIPA), and compound of formula (Xe; CDEA). More preferred embodiments of compound of formula (IVa) and compound of formula (IVb) are selected from the group consisting of compound of formula (Xa; MEA), compound of formula (Xb; DEA), compound of formula (Xc; DIP A) and compound of formula (Xd; MIPA).

In reaction (II), further anilines can be present, preferably 1, 2 or 3 further anilines, such as compound of formula (XI; AM), which are different from compound of formula (IVa) and from compound of formula (IVb); wherein R2, R3 and R6 are identical or different and independently from each other selected from the group consisting of H, C ₁ - ₄ alkyl and Cl, preferably wherein R2 and R6 are identical or different and independently from each other selected from the group consisting of H, C ₁ - ₄ alkyl and Cl and R3 is selected from the group consisting of H or C ₁ - ₄ alkyl.

The presence of such further aniline in reaction (II) results in the respective mixtures of asymmetrical methylene-bis-anilines with respective symmetrical methylene-bis- anilines, which are possible to be obtained from any of the combinations of two anilines out of all anilines which are present in reaction (II); the use of such mixtures in reaction (I) results in the respective mixtures of asymmetrical methylene-bis-maleimides with symmetrical methylene-bis-maleimides. Table 2 shows an embodiment, wherein three anilines have been used in reaction (II) and the mixtures which are thereby obtained from reaction (II) and thereafter from reaction (I).

Further subject of the invention is a compound of formula (I); with the compound of formula (I) as defined herein, also with all its embodiments.

Further subject of the invention is a mixture of compound of formula (I) with compound of formula (Vila; BMIL) and compound of formula (Vllb; BMIR); with the compound of formula (I), the compound of formula (Vila; BMIL) and the compound of formula (Vllb; BMIR) as defined herein, also with all their embodiments.

Further subject of the invention is the use of compound of formula (I) for the preparation of resins; with the compound of formula (I) as defined herein, also with all its embodiments.

EXAMPLES

Abbreviations:

A1 amine 1 A2 amine 2

A3 amine 3

Mp melting point p-Tos p-toluenesulfonic acid monohydrate wt% weight percent Yd Yield

MEK methyl ethyl ketone DMF A ^f , A-Dimethylformamide

Materials Maleic anhydride CAS 108-31-6, >=99.0%, Sigma- Aldrich p-toluenesulfonic acid monohydrate CAS 6192-52-5, >=98%, Sigma- Aldrich Methods (1) GC

Instrument parameters

Column OPTIMA- 1 (30 m x 0.32 mm x 0.35 micrometer) Temperature program:

Initial; time 90 °C; 0 min

Ratel; Final 1; Time 1 30 °C/min; 200 °C; 0 min

Rate2; Final 2; Time 2 20 °C/min; 260 °C; 0 min

Rate3; Final 3; Time 3 2 °C/min; 280 °C; 0.33 min

Run Time 17.00 min

Equilibration Time 3 min

Mode Cons flow

Carrier gas H ₂

Flow 2.0 mL/min

Split ratio 50:1

Inlet Temperature 250 °C

Injection Volume 1 microliter (pL)

Detector: FID

Detector temperature 320 °C

Sample preparation:

Sample is heated to 50°C and 200 mg sample is added to 1 mL methanol in a 2 mL GC vial and homogenized by shaking.

(2) HPLC-UV

HPLC-UV is a reversed phase HPLC using UV Detection. Column: Xbridge Shield 150 mm x 3.0 mm x 3.5 pm or similar Pump: min. pressure: 5 bar max. pressure: 400 bar max. flow gradient: 100 mL/min

Eluent A: 20 mmol aqueous Ammonium acetate pH 3.0

Eluent B : Acetonitrile

Injection:

Inj ection volume 10 microlitre (pL) Detector: Detector Type UV

Wavelength 269 nm

Column oven:

Temperature 40 °C Sample preparation:

20 mg +/- 4 mg sample were dissolved in 20 mL of acetonitrile.

The LOD (Limit of Detection) was 0.02 area-%.

LOQ (Limit of Quantification) was 0.07 area-%.

(3) Calculation of Yield:

The percentage determined by a GC or HPLC chromatogram are the area percentage of the respective signal.

Respective reaction yields of the mixtures are calculated on the basis of the sum of the molar mass of each single compound of the mixture multiplied by the respective area % content determined by GC or HPLC respectively. General Procedure 1: Preparation of mixed compound of formula (II)

A mixture of different aromatic amines (a total of ca. 2 mol eq, see specific eq in Tables 1 A, IB and 1C) is dissolved in propan-2-ol (4.73 mol eq) and water (2.16 mol eq). To the stirred mixture, sulfuric acid (96.0 wt%, 1.81 mol eq) is added and the mixture is heated to 60 °C. Over a period of 1 h an aqueous formaldehyde solution (37 wt%, 1.08 mol eq) is added over a dip pipe. Afterwards, the reaction mixture is stirred for 5 h at 60 °C. Temperature is adjusted to 25 °C and aqueous sodium hydroxide solution (25 wt%., 3.80 mol eq) is added. The product is extracted with chloroform followed by washing with water. The organic phase is isolated and the organic solvent is fully removed under vacuum to afford a mixture of symmetrical (sym) and unsymmetrical (asym) compound of formula (II) as a brown melt.

Tables 4 A, 4B and 4C show the examples which are prepared according to General Procedure 1

General Procedure 2: Preparation of mixed compound of formula (I)

A melt of mixed compound of formula (II) (1 mol eq, prepared according to General Procedure 1) is dissolved in xylene (17 mol eq) to provide a solution of mixed compound of formula (II)in xylene. In a reactor equipped with a Dean-Stark trap, xylene (17 mol eq) is charged and p-toluene sulfuric acid monohydrate (0.46 mol eq) and maleic anhydride (2.30 mol eq) are dissolved. The mixture is heated to reflux. The previously prepared solution of mixed compound of formula (II) in xylene is added over 1 h whilst the reaction mixture is kept under reflux. After the dosage of the solution of mixed compound of formula (II) in xylene, the reaction mixture is kept under reflux until no more water is collected in the Dean- Stark-trap, typical times are 3 to 5 h. Then about 20 vol% of the xylene is removed by distillation.

The temperature is adjusted to 90 °C and aqueous sodium hydroxide (10 wt%, 5.7 mol eq) is added. The mixture is stirred for 30 min at 90 °C. The aqueous phase is separated and the organic phase is subsequently washed with 3 portions of water (4 mol eq each portion). The organic phase is isolated and the organic solvent is fully removed under vacuum to afford the mixed compound of formula (I) as a brown melt.

Table 5 shows the examples which are prepared according to General Procedure 2.

(4) Solubility analysis: Solubility was determined using a Mettler Toledo halogen dryer (Mettler-Toledo GmbH; GieBen, Germany). A saturated solution of each compound was prepared in the respective solvent and the dissolved amount (wt%) in the liquid phase determined after filtration using a syringe filter ( 1 p pore size) on the halogen dryer. The results of the solubility analysis are summarized in Table 6 (BMPI-300 is a 1:1 mixture ofBMIDEA (formula Villa) and BMIMIPA (formula VIIIc); BMI-5100 is BMIMEA (formula Vllld)).

(*), this is an emulsion, rather than a clear solution

(5) Gel time analysis:

Gel times were determined using a GELNORM ^® Gel Timer (Gel lnstrumente AG, Thalwil, Switzerland), according to manufacturer’s instructions. The results of the solubility analysis are summarized in Table 7. (6) Viscosity analysis:

Viscosity was determined using a Brookfield LV-II - Pro viscosimeter with Thermosel System (BROOKFIELD ENGINEERING LABORATORIES, INC.; Middleboro, MA, USA), according to manufacturer’s instructions. The results of the solubility analysis are summarized in Table 8 (dashes indicate temperatures below melting point). The compounds of formula (I) according to the invention were observed to have lower viscosities than eutectic mixtures of the corresponding symmetrical bis maleimide derivatives. Table 8