GB2279950A - Synthesis of N,N'-bis (2-hydroxyethyl) ethylenediamines - Google Patents

Abstract

A method is provided for preparing N,N'-bis(2-hydroxyethyl)ethlyenediamines and, in particular, 2,2-[ethanediylbis(alkylimino)]bisethanol which is a potential precursor to triazacyclononane rings. These ring systems are useful as a ligand with manganese in a catalyst for bleaching. The method involves self-condensing an appropriate amino alcohol in the presence of hydrogen, solvent and a supported bimetallic catalyst comprising copper.

Description

SYNTHESIS OF N,N'-BIS(2-HYDROXYETHYL)ETHYLENEDIAMINES The invention relates to the synthesis of N,N'-bis(2hydroxyethyl)ethylenediamines and, in particular, 2,2 [ethanediylbis(alkylimino)]bisethanols.

Such materials are potential precursors to triazacyclononane rings. These nitrogen containing ring systems, especially 1,4,7-trimethyl-1,4,7-triazacyclononane, are useful as a ligand with manganese in a catalyst for bleaching.

Recently a series of manganese complexes which are exceptionally active bleach catalysts have been identified.

The catalytic performance of the complex may, at least in part, be attributed to the ligand, 1,4,7-trimethyl-1,4,7triazacyclonanane, referred to hereinafter as 1,4,7-Me3TACN, or higher alkyl derivatives thereof. A particularly preferred complex has the general structure:

However, the complex suffers from disadvantages associated with the preparation of the ligand. The synthesis of 1,4,7 Me3TACN has been described principally by Richman and Atkins in Organic Synthesis, 58, pages 86-98, (1978). The process described therein, whilst suitable for small scale preparation, is not amenable to large scale production.

Furthermore, the process consists of six synthetic steps, involves the production of a large number of waste products, including solvents which are not recyclable, and is expensive. We have found a process for preparing a precursor to the aforementioned ligands which does not suffer from the disadvantages of the prior art. Broadly we have found N,N' bis(2-hydroxyethyl)ethylenediamines can be made from a cheap starting material in one step in the presence of a catalyst.

Accordingly the invention provides a process for preparing a compound of formula (I)

wherein: - R1 is a C1 - C3 alkyl or alkenyl; the process comprising self-condensing an aminoalcohol of formula

in the presence of hydrogen, a solvent with a boiling point adequate to maintain the reaction temperature by ref fluxing and a supported bimetallic dehydrogenation/ hydrogenation or reduction/oxidation catalyst comprising copper.

Metal catalysed reaction of alcohols with amines is known, for example, A Baiker, Catal. Review.-Sci Eng., 27, 653 (1985). Generally, amines are preferentially alkylated by alcohols and to a much small extent, as a result of disproportionation, alkylation by the amine may also occur.

Such a reaction with a bifunctional compound, where the hydroxy and methylamino groups form part of the same molecule, would be expected to proceed mainly through alkylation of the methylamino group by carbon formerly substituted by an hydroxyl group and, to a lesser extent, through formal alkylation of the methylamino group by carbon formerly substituted by a methylamino group. Thus, as a result of reptition of both alkylations a broad range oligomers would be formed. It is, therefore, surprising that in the process of the present invention a compound of formula (I) is formed as a major product.

The process of the invention is particularly suitable for preparing compounds of formula (I) in which R1 is a methyl group. Such a compound is a precursor to 1,4,7-Me3TACN. In this case, the starting material for the process is Nmethylaminoethanol.

Preferably, the catalyst comprises, in addition to copper, a second metal selected from nickel, platinum and palladium or a compound thereof such as nickel oxide. Especially preferred are copper/palladium catalyst, particularly where the ratio of Cu to Pd is 1:1, and copper/nickel oxide catalysts, particularly where the ratio of copper to nickel is 4:1.

The support for the bimetallic catalyst is preferably selected from alumina, aluminosilicates such as zeolite X and clays such as Laponite.

Suitable solvents for the reaction include xylene, DMF, ethylene glycol, triglyme, diglyme, decaline and mixtures thereof. A preferred solvent contains at least some diglyme and is, most preferably, diglyme containing about 10% by weight decaline and from 5 to 15% by weight ethylene glycol.

Although not the optimum solvent, it has been found that the presence of ethylene glycol in the reaction mixture, together with at least one other solvent has a beneficial effect on the yield of product. Preferably, ethylene glycol is present in an amount of from 5 to 15% by weight.

The following non-limiting examples illustrate the invention further.

Examples The following catalysts were used in the examples:

Catalyst Active Component Support Metal Content 1 Cu 60% CuO Alumina-Y 2 Cu z=0.1 Zeolite X 3 Cu/NiO 45% CuO Alumina7 11% Nio 4 Cu/NiO Cu:Ni=4 Zeolite X z=0.3 5 Cu/Nio Cu:Ni=4 Laponite 6 Cu/Pd Cu:Pd=l Zeolite X z=0,09 7 Cu/ZnO 61% Cu Alumina-y 36% ZnO 8 Ni Niboride They were prepared as follows:: I) Prenaration and activation of alumina supported metal catalvsts 2 molar solutions of metal nitrates (M = Al, Cu, Ni) were prepared and mixed in such a way to obtain the desired ratios of metals (for a copper only catalyst Cu/Al = 0.7; for a mixed copper/nickel catalyst Cu/Al = 0.48, Ni/Al = 0.12).

The resulting solutions were added to a beaker containing 100ml demineralised water at rate of approximately 3ml/min.

The solution was maintained at a temperature of 800C and stirred vigorously. Simultaneously a 2 molar solution of Na2CO3 was added at such rate as to keep the pH between 7 and 7.5 until addition of the metal nitrate was complete.

Thereafter, the reaction mixture was stirred for a further hour at 800C before cooling to room temperature overnight.

The resulting precipitate was collected and washed extensively with water at a temperature of 80-900C. The catalyst was dried at 1000C and calcined at 3500C for at least 16 hours.

Prior to use the catalyst was activated by heating it slowly under hydrogen (1 bar) from room temperature to approximately 140-1500C. After 30 minutes the temperature was increased to 2000C and maintained at this temperature for a further 30 minutes.

II) Preparation and activation of zeolite X supported metal catalysts To a suspension of 50g zeolite X in water, 1 litre, was added 2.54g CuSO4 (the amount of Cu2+ needed to exchange 10% of Na+ ie z=0.1). The suspension was maintained at a temperature of 800C and stirred for one hour. It was then cooled to room temperature and the Cu2+ exchanged zeolite collected and dried at 1000C.

The same procedure was adopted to exchange 6% of Na+ for Ni2+, (ie 2.3g NiCl2.6H20, z=0.06). The zeolite supported CuO/NiO catalyst was suspended in water and made alkaline with Na2CO3 (10.5 < pH < 11). The catalyst was collected, dried (1000C) and calcined at 3500C for at least 16 hours to produce CuO/NiO/zeolite X (Cu:Ni =4, z =0.30).

In the case of palladium containing catalysts Pd(NH3)4Cl2, (1.38g) prepared from 1g PdCl2 in 100ml of water and 5ml ammonium hydroxide, was used.

The order for exchanging the metals was always that Pd should be exchanged for Na+ first, followed by Cu and finally Ni.

After exchange of Na+ by Pd2+, the resulting catalyst was calcined to remove ammonia ligands.

Prior to use the catalyst was activated by heating it slowly under hydrogen (1 bar) from room temperature to 2100C and maintained at this temperature for 30 minutes.

III) Preparation and activation of a Laponite supported Cu/NiO (4:1) catalyst To a suspension of Laponite XLS, 100g, which was swelled in water, 1.4 litres, for one day was added Cu (II) acetate monohydrate, 12.0g 0.06 mole, and Ni (II) acetate tetrahydrate, 3.7g 0.015 mole. The resulting solution was maintained at a temperature of 800C and stirred vigorously for 1 hour. Lithium hydroxide, 100ml of 1.5N, was added and the viscous gel washed extensively with water, freeze dried and calcined at 3500C for at least 16 hours. Prior to use the catalyst was activated by heating it slowly from room temperature to 2100C and maintained at this temperature for 30 minutes.

The preparation of the Ni boride catalyst is described by C A Brown et al, J Am Chem Soc., 85, 1003, (1963).

Svnthesis of 2,2'-rl,2-ethanedivlbis(methvlimino)l-bisethanol The reaction was carried out as follows. Hydrogen gas was blown through a 250 ml flask equipped with a thermometer, stirrer, a Vigreux column and dropping funnel. The flask was immersed in an oil bath. N-methylaminoethanol, 15g 0.2mole, was added dropwise over approximately two hours to a stirred solution of ethylene glycol, 6.2g 0.lmole, decaline, 5g, and activated catalyst, 3g, in diglyme, 40ml, heated in an oil bath at 1750C. Water formed during the reaction was removed as an azetrope with decaline by the rectifying column. The reaction mixture was maintained at 1750C for a further 2 to 6 hours. Samples were removed from the reaction mixture periodically and analysed by GLC.

The reaction was found to proceed to form mainly 2,2' - [ethanediylbis (methylimino) ] -bisethanol

or mainly a monooxzolidine of formula.

Where necessary, products A and B were separated by GLC (CSORB WHP 100/120 mesh with 3% OV-1 ex Chrompack). Product A had a boiling point of 980C at 0.lmmHg and Product B a boiling point of 760C at O.lmmHg.

These two materials were indentified by 1H nmr, 13C nmr and mass spectrophometry as below:

Compound H NMR 13C NMR Mass Hx # (ppm) m 1 J (Hz) Cx #(ppm) m J(Hz) 4 H1 3.44 t 4H 6.3 C1 60.8 t 131 a N N H2 3.40 t 4H 6.3 C2 60.2 t 139 # 176 2 H4 2.41 s 4H - C4 56.6 t 128 Ha 2.18 s 6H - Ca 44.0 q 133 1 OH HO H2 4.06 dd H 2.2 C2 91.0 10.2 H4a 2.50 dd 1H 2.5 11.5 C4 54.6 H4b 1.95 td 1H 3.4 11.5 H5a 3.80 dd 1H 3.4 O 11.5 C5 65.6 5 H5b 3.58 td 1H 2.5 n.d. 174 6 2 11.5 N 4 H6a 2.63 dd 1H 2.2 a N 11.0 C6 58.3 b H6b 2.09 dd 1H 10.2 8 11.0 9 H8 2.81 t 2H 5.0 C8 55.9 OH H9 3.47 m 2H n.d. C9 58.4 Ha,b 2.20 s 3H - Ca,b 46.2 2.37 s 3H - 36.2 The results of carrying out the reaction with the variety of catalysts listed above is given in Table 1 below: Table 1

Catalyst Yield of % Yield of Yield of % Yield of Product A/g A Product B/g B 1 0.2 2 7.1 61 2 1.4 12 6.8 59 3 8.2 70 0.1 1 3* 6.7 57 1.2 10 4 5.1 43 2.5 22 5 6.5 55 1.9 16 6 8.0 68 0.3 3 7 0 0 6.6 57 8 0.3 3 8.5 73 * repeat of experiment with catalyst 3 but in the absence of ethylene glycol.

Claims (4)

1. A process for preparing a compound of formula (I)

wherein: - R1 is hydrogen or a C1 - C3 alkyl or alkenyl; the process comprising self-condensing an aminoalcohol of formula

in the presence of hydrogen, a solvent with a boiling point adequate to maintain the reaction temperature by refluxing and a supported bimetallic dehydrogenation/hydrogenation or reduction/oxidation catalyst comprising copper.

2. A process according to claim 1 wherein the catalyst comprises a second metal selected from nickel, platinum and palladium and compounds thereof.

3. A process according to claim 1 wherein ethylene glycol is added to the aminoalcohol in the reaction mixture.

4. A process according to claim 1 wherein the support is selected from alumina, aluminosilicates and clays.