WO2021174523A1

WO2021174523A1 - A method for preparing alkylated amines

Info

Publication number: WO2021174523A1
Application number: PCT/CN2020/078160
Authority: WO
Inventors: Fan Jiang; Stephane Streiff; Willinton Yesid HERNANDEZ ENCISO
Original assignee: Rhodia Operations
Priority date: 2020-03-06
Filing date: 2020-03-06
Publication date: 2021-09-10
Also published as: EP4114819A1; EP4114819A4; CN115244029A

Abstract

The present invention pertains to a method for preparing an alkylated amine by reacting a primary or secondary amine with an alcohol in the presence of hydrogen, a metal catalyst supported by photosensitive titanium oxide, and UV irradiation. Advantageously, the reaction can be carried out under mild reaction conditions.

Description

A method for preparing alkylated amines

TECHNICAL FIELD

The present invention pertains to a method for preparing alkylated amines.

BACKGROUND

N, N, N', N” , N” -pentamethyldiethylenetriamine (PMDTA) is used in the formation of rigid foam polyurethane. Current technology for PMDTA production relies on the methylation of diethylenetriamine (DETA) in the presence of hydrogen by using formaldehyde as methyl source. This methodology is selective towards PMDTA. However, the use of formaldehyde (CMR compound) raises HSE concerns.

For example, US Patent No. 5105013 teaches a process for the preparation of permethylated amines, particularly pentamethyldiethylenetriamine, by the reductive methylation of diethylenetriamine in the presence of hydrogen, aqueous formaldehyde, a catalyst, and a solvent. The reaction was carried out in two reaction phases and the flow rate of formaldehyde must be well controlled.

RSC Adv., 2015, 5, 14514–14521 reports a series of TiO ₂ supported nano-Pd catalysts (Pd/TiO ₂) were prepared and used for the N, N-dimethylation of different amines and nitro compounds with methanol under UV irradiation at room temperature. The working atmosphere was argon.

There are some well-known processes for alkylation of amines using alcohol as alkylating reagent in the presence ofhydrogen and catalysts other than photocatalyst. For example, Baiker_et_al Helvetica Chimica Acta Vol. 61 Fasc 3 (1978) Nr 1121169-1174 and T. Yamakawa et al. Catalysis Communications 5 (2004) 291–295 disclose the use of heterogeneous metal catalysts, especially copper-based catalyst. ACS Sustainable Chem. Eng. 2019, 7, 1, 716-723 reports the use of a homogeneous ruthenium-based catalyst. However, all of the reactions required high temperature and high pressure of hydrogen.

Hence, there is still a need to develop an environmentally friendly method to alkylate amines in high yield and selectivity under mild reaction conditions, which can overcome the drawbacks in prior arts.

SUMMARY OF THE INVENTION

The present invention therefore pertains to a method for preparing an alkylated amine by reacting a primary or secondary amine with an alcohol in the presence of hydrogen, a metal catalyst supported by photosensitive titanium oxide, and UV irradiation.

The method of the invention enables to alkylate amines by using an environmentally friendly alkylation agent with higher yield.

Advantageously, the reaction according to the present invention can be carried out under low hydrogen pressure and low reaction temperature.

The invention also concerns a mixture comprising:

(i) A primary or secondary amine,

(ii) An alcohol,

(iii) Hydrogen, and

(iv) A metal catalyst supported by photosensitive titanium oxide.

Other subjects and characteristics, aspects and advantages of the present invention will emerge even more clearly on reading the detailed description and the examples that follow.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is an image of H ₂ pressure-yield curve of reaction of octylamine with methanol of Example 8.

DEFINITIONS

Throughout the description, including the claims, the term "comprising one" should be understood as being synonymous with the term "comprising at least one" , unless otherwise specified, and "between" should be understood as being inclusive of the limits.

As used herein, the terminology " (C _n-C _m) " in reference to an organic group, wherein n and m are both integers, indicates that the group may contain from n carbon atoms to m carbon atoms per group.

The articles “a” , “an” and “the” are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.

The term “and/or” includes the meanings “and” , “or” and also all the other possible combinations of the elements connected to this term.

It is specified that, in the continuation of the description, unless otherwise indicated, the values at the limits are included in the ranges of values which are given.

Ratios, concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such a range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also all the individual numerical values or sub-ranges encompassed within that range as if each numerical value or sub-range is explicitly recited.

DETAILS OF THE INVENTION

In some embodiments, the primary or secondary amine used in the method according to the present invention may have the general formula (I) :

R ¹R ²NH (I)

R ¹ and R ², independently from each other, may represent hydrogen, or a straight, branched or cyclic hydrocarbon group, which is optionally interrupted by one or several heteroatoms and/or which is optionally substituted by one or several functional groups. R ¹ and R ² are not both hydrogen at the same time. Said heteroatoms can be O, S, F, or N.

R ¹ and R ², independently from each other, may represent hydrogen, an alkyl, an alkenyl, an aryl, a cycloalkyl or a heterocyclic group.

R ¹ and R ², independently from each other, can notably be hydrogen, a C ₂-C ₂₀ alkyl, alkenyl, aryl group or heterocyclic group, and preferably hydrogen, a C ₃-C ₁₀ alkyl, alkenyl, aryl group or heterocyclic group.

Advantageously, R ¹ is hydrogen and R ² is an alkyl group selected from a group consisting of ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl and n-decyl.

In some embodiments, the primary or secondary amine according to the present invention may have the general formula (II) :

wherein:

- n is an integer between 0 and 20;

- m is an integer between 1 and 3;

- p is an integer between 0 and 2, and

- p+m=3.

In a preferred embodiment, the compound having general formula (II) is a compound having general formula (III) :

wherein n is an integer between 0 and 20, preferably between 0 and 9 and more preferably between 0 and 4.

In another preferred embodiment, the compound having general formula (II) is a compound having general formula (IV) :

In a third preferred embodiment, the compound having general formula (II) is a compound having general formula (V) :

The compound having general formula (II) can be selected from the group consisting of dimethylenetriamine, diethylenetriamine, dipropylenetriamine, dibutylenetriamine, dipentylenetriamine, dihexylenetriamine, diheptylenetriamine, dioctylenetriamine, dinonylenetriamine, didecylenetriamine, methylenediamine, ethylenediamine, propylenediamine, butylenediamine, pentylenediamine, hexylenediamine, heptylenediamine, octylenediamine, nonylenediamine, and decylenediamine, triaminomethylamine, tris (2-aminoethyl) amine, tris (3-aminopropyl) amine, tris (4-aminobutyl) amine, tris (5-aminopentyl) amine, tris (6-aminohexyl) amine, tris (7-aminoheptyl) amine, tris (8-aminooctyl) amine, tris (9-aminononyl) amine and tris (10-aminodecyl) amine.

Preferably, the compound having the general formula (II) can be selected from the group consisting of diethylenetriamine, dipropylenetriamine, dibutylenetriamine, dipentylenetriamine, ethylenediamine, propylenediamine, butylenediamine and pentylenediamine.

The alcohol used in the method according to the present invention may have the general formula (VI) :

R ³OH (VI)

wherein R ³ is an alkyl, an alkenyl or an alkynyl.

Preferably, R ³ may be a straight or branched. More preferably, R ³ may be a C ₁-C ₁₀ straight or branched alkyl.

Examples of the alcohol having general formula (VI) are methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-decanol, 2-propanol, 2-butanol and 3-butanol.

Preferably, the alcohol having general formula (VI) can be selected from the group consisting of methanol, ethanol, 1-propanol and 2-propanol.

The alcohol may comprise traces of corresponding aldehyde and/or carboxylic acid. For example, methanol may comprise traces of formaldehyde and/or formic acid, ethanol may comprise traces of acetaldehyde and/or acetic acid, and propanol may comprise traces of propionaldehyde and/or propanoic acid. Advantageously, the alcohol may contain 0.01-10000 ppm corresponding aldehyde and/or carboxylic acid.

It shall be understood by the skilled person that the primary or secondary amine can be partially or completely alkylated by the method according to the present invention.

Preferred reactions of the present invention are the following:

R ³, n, m and p have the same meanings as above defined.

R ¹ and R ³ have the same meanings as above defined.

Examples of preferred reactions are the following:

- Reaction of pentylamine with methanol to produce dimethylpentylamine;

- Reaction of hexylamine with methanol to produce dimethylhexylamine;

- Reaction of heptylamine with methanol to produce dimethylheptylamine;

- Reaction of octylamine with methanol to produce dimethyloctylamine;

- Reaction of nonylamine with methanol to produce dimethylnonylamine;

- Reaction of diethylenetriamine with methanol to produce N, N, N', N” , N” -pentamethyldiethylenetriamine;

- Reaction of diethylenetriamine with ethanol to produce N, N, N', N” , N” -pentaethyldiethylenetriamine;

- Reaction of diethylenetriamine with 1-propanol to produce N, N, N', N” , N” -pentapropyldiethylenetriamine;

- Reaction of diethylenetriamine with 2-propanol to produce N, N, N', N” , N” -pentaisopropyldiethylenetriamine;

- Reaction of dipropylenetriamine with methanol to produce N, N, N', N” , N” -pentamethyldipropylenetriamine;

- Reaction of dipropylenetriamine with ethanol to produce N, N, N', N” , N” -pentaethyldipropylenetriamine;

- Reaction of dipropylenetriamine with 1-propanol to produce N, N, N', N” , N” -pentapropyldipropylenetriamine;

- Reaction of dipropylenetriamine with 2-propanol to produce N, N, N', N” , N” -pentaisopropyldipropylenetriamine;

- Reaction of ethylenediamine with methanol to produce N, N, N', N'-tetramethylethane-1, 2-diamine;

- Reaction of ethylenediamine with ethanol to produce N, N, N', N'-tetraethylethane-1, 2-diamine;

- Reaction of ethylenediamine with 1-propanol to produce N, N, N', N'-tetrapropylethane-1, 2-diamine;

- Reaction of ethylenediamine with 2-propanol to produce N, N, N', N'-tetraisopropylethane-1, 2-diamine;

- Reaction of propylenediamine with methanol to produce N, N, N', N'-tetramethylpropane-1, 3-diamine;

- Reaction of propylenediamine with ethanol to produce N, N, N', N'-tetraethylpropane-1, 3-diamine;

- Reaction of propylenediamine with 1-propanol to produce N, N, N', N'-tetrapropylpropane-1, 3-diamine;

- Reaction of propylenediamine with 2-propanol to produce N, N, N', N'-tetraisopropylpropane-1, 3-diamine;

- Reaction of tris (2-aminoethyl) amine with methanol to produce tris [2- (dimethylamino) ethyl] amine;

- Reaction of tris (2-aminoethyl) amine with ethanol to tris [2- (diethylamino) ethyl] amine;

- Reaction of tris (2-aminoethyl) amine with 1-propanol to produce tris [2- (di-n-propylamino) ethyl] amine;

- Reaction of tris (2-aminoethyl) amine with 2-propanol to produce tris [2- (di-iso-propylamino) ethyl] amine.

- Reaction of tris (3-aminopropyl) amine with methanol to produce tris [3- (dimethylamino) propyl] amine;

- Reaction of tris (3-aminopropyl) amine with ethanol to tris [3- (diethylamino) propyl] amine;

- Reaction of tris (3-aminopropyl) amine with 1-propanol to produce tris [3- (di-n-propylamino) propyl] amine;

- Reaction of tris (3-aminopropyl) amine with 2-propanol to produce tris [3- (di-iso-propylamino) propyl] amine.

The metal supported on photosensitive titanium oxide is not particularly limited. Advantageously, the metal is a noble metal. The noble metals are metals that are normally valuable and resistant to corrosion and oxidation in moist air. It can be selected from a group consisting of ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold. Palladium, gold, platinum and silver are preferred among these noble metals and palladium is more preferred.

In some embodiments, one and only one noble metal is supported on photosensitive titanium oxide. The loading of noble metal on photosensitive titanium oxide in this embodiment may be in the range of 0.01wt%to 10wt%, preferably 0.01wt%to 2wt%and more preferably 0.01wt%to 1.5wt%.

In some embodiments, at least two metals are supported on photosensitive titanium oxide. Said two metals can be any combination of palladium, gold, platinum, silver, copper and molybdenum. The loading of each metal on photosensitive titanium oxide in this embodiment depends on the specific metal. Advantageously, at least Pt-Au, Pd-Au or Pt-Pd are supported on photosensitive titanium oxide. The loading of Pd, Pt or Au on photosensitive titanium oxide may be in the range of 0.01wt%to 10wt%, preferably 0.01wt%to 2wt%and more preferably 0.01wt%to 1.5wt%.

The average primary particle size of metal nanoparticles on photosensitive titanium oxide is from 0.5 to 40 nm and preferably from 1 to 20 nm, which is measured using transmission electron microscopy (TEM) .

For TEM analysis, a JEOL 2100 with Filament LaB6 having an acceleration voltage of 200 kV equipped with a camera Gatan 832 CCD was used. As support, square 230 mesh TEM support grids (copper) were used. The magnification factor had a range of '10,000～'600,000. For 50 nm: magnification factor was 40,000～50,000; for 20 nm: 60,000～120,000; for 10 nm: 250,000; for 5 nm: 400,000; for 2 nm: 500,000～600,000. Samples of 0.1wt%nanoparticles in methanol suspension were measured. The obtained results were analyzed using the DigitalMicrograph software. For each sample, two pictures were taken and a total of 100 nanoparticles were analyzed for obtaining the described size distribution. From this size distribution, the average particle size of the nanoparticles was obtained. The software used to measure the size of the nanoparticles was ImageJ thereby approximating the particles to be spherical. After setting the scale, the maximum diameter of the particles was manually measured one by one to a total number of particles measured of 100. Every particle has been measured 3 times to obtain an average size.

Photosensitive titanium oxide (TiO ₂) , also referred to as titania, is found in three known crystal forms, rutile, anatase and brookite. According to the present invention, anatase and rutile are preferred crystal forms. In a preferred embodiment, photosensitive titanium oxide is a mixture of anatase type and rutile type crystals.

The BET surface area of crystals of photosensitive titanium oxide may be preferably from 10 to 600 m ²/g and preferably from 30 to 400 m ²/g.

The term “specific surface area” is understood to mean the BET specific surface area determined by nitrogen adsorption in accordance with standard ASTM D 3663-78 laid down from the Brunauer-Emmett-Teller method described in the periodical “The Journal of the American Chemical Society, 60, 309 (1938) ” .

In a preferred embodiment, photosensitive titanium oxide is in anatase crystal form and has a BET surface area in the range of 70 to 120 m ²/g and preferably 80 to 100 m ²/g. Example of such photosensitive titanium oxide is PC105 from Cristal.

In another embodiment, photosensitive titanium oxide is in anatase type crystal form and has a BET surface area in the range of 300 to 400 m ²/g and preferably 330 to 370 m ²/g. Example of such photosensitive titanium oxide is PC500 from Cristal.

In a third embodiment, photosensitive titanium oxide is a mixture of anatase type and rutile type crystals, with an anatase content of 80–90%by weight and a rutile content of 10–20%by weight. Photosensitive titanium oxide in this embodiment may have a BET surface area in the range of 20 to 80 m ²/g and preferably 35 to 65 m ²/g. Example of such photosensitive titanium oxide is P25 from Evonik. Photosensitive titanium oxide in this embodiment may also have a BET surface area in the range of 50 to 130 m ²/g and preferably 70 to 110 m ²/g. Example of such photosensitive titanium oxide is P90 from Evonik.

Advantageously, photosensitive titanium oxide used in the method according to the present invention is P25 or P90, and preferably P90.

Some typical ultraviolet light equipment, such as Xenon or LED lamp, can realize UV radiation. Preferably, the irradiation powder of UV light may be from 1 to 320W, preferably from 8 to 310W.

The supported metal catalyst according to the present invention can be obtained by various known methods. For example, deposition-precipitation- reduction method: RSC Adv., 2015, 5, 14514–14521 and photo-deposition method: J. Org. Chem. 2017, 82, 5959-5965.

Advantageously, the supported metal catalyst is prepared by photo-deposition method. In a typical method, it may comprise following steps:

a) Preparing a metal precursor aqueous solution,

b) Mixing photosensitive titanium oxide with the solution prepared at step a) ,

c) Stirring the mixture obtained at step b) under inert atmosphere in the absence of light irradiation at room temperature for a proper time,

d) Stirring the mixture obtained at step c) under inert atmosphere and UV irradiation at room temperature for a proper time,

e) Centrifugating the mixture obtained at step d) to obtain a solid product,

f) Washing the solid product obtained at step e) by a solvent until the pH value becomes neutral,

g) Drying the solid product obtained at step f) .

Preferably, the concentration of the metal precursor in step a) may be in the range of 0.0005 mol/L to 0.50 mol/L and preferably from 0.001 mol/L to 0.05 mol/L.

Preferably, the irradiation powder of UV light in step d) may be from 1 to 320W, preferably from 8 to 310W.

Preferably, the solvent in step f) may be water and preferably deionized water.

The weight ratio of the supported metal catalyst to the primary or secondary amine is from 0.001 to 100 and preferably from 0.01 to 10.

The weight ratio of the primary or secondary amine to the alcohol may be from 0.0001 to 0.5 and preferably from 0.001 to 0.2.

According to the method of the present invention, in a preferred embodiment, the alcohol is the reactant and also the only solvent of the primary or secondary amine. It can understood by the skilled person that the reaction may also be carried out in the presence of a second solvent other than the alcohol as long as the second solvent does not participate in the reaction in place of the alcohol. Examples of such solvent are water, formaldehyde (traces) , formic acid (traces) , benzene, toluene, dimethyl ether, etc.

The concentration of the primary or secondary amine in the solvent may be from 0.01 wt%to 50wt%and preferably from 0.1wt%to 20wt%.

Although not specifically limited, the reaction of the primary or secondary amine with the alcohol is desirably carried out under a hydrogen pressure in a range of 0.1 to 20 bar, and more preferably 0.5 to 12 bar. Optionally, hydrogen may be added during the reaction to make up for the consumption or continuously circulated through the reaction zone.

The reaction may be carried out in the presence of an inert atmosphere such as N ₂ or Ar.

The reaction time may be from 0.5 to 100 h and preferably from 2 to 60 h.

The reaction temperature may be from 0℃ to 100℃, and preferably from 10℃ to 50℃ and more preferably room temperature.

The invention also concerns a mixture comprising:

(i) A primary or secondary amine,

(ii) An alcohol,

(iii) Hydrogen, and

(iv) A metal catalyst supported by photosensitive titanium oxide.

The mixture may further comprise a second solvent selected from the group consisting of water, formaldehyde, formic acid, benzene, toluene and dimethyl ether.

The mixture may further comprise an alkylated amine prepared by the method of the invention.

The primary or secondary amine, the alcohol and the metal catalyst has the same meaning as above defined.

EXAMPLES

The technical features and technical effects of the present invention will be further described below in conjunction with the following examples so that the skilled in the art would fully understand the present invention. It will be readily understood by the skilled in the art that the examples herein are for illustrative purposes only and the scope of the present invention is not limited thereto.

Materials

-

TiO ₂ P25, CAS No. 13463-67-7, 99.5%, Evonik

-

TiO ₂ P90, CAS No. 13463-67-7, 99.5%, Evonik

- CristalACTIV ^TM PC105, CAS No. 13463-67-7, Cristal ACTIV

- CristalACTIV ^TM PC500, CAS No. 13463-67-7, Cristal ACTIV

- Gold (III) Chloride hydrate, CAS No. 27988-77-8, 99.995%, Sigma-aldrich

- Silver nitrate, CAS No. 7761-88-8, AR, Sino Pharm

- Palladium chloride, CAS No. 7647-10-1, 99.5%, Sigma-aldrich

- Hydrochloric acid, CAS No. 7647-01-0, 36.0-38.0%, Sino Pharm

- Sodium hydroxide, CAS No. 1310-73-2, AR, Sino Pharm

- Sodium borohydride, CAS No. 16940-66-2, 96%, Sino Pharm

- Octylamine, CAS No. 111-86-4, 99%, J&K

- Bisphenyl, CAS No. 92-52-4, 99.5%, J&K

- Methanol, CAS No. 67-56-1, 99.9%, Merck

- Iso-propanol, CAS No. 67-63-0, 99.9%, Merck

- Diethylenetriamine, CAS No. 111-40-0, 99%, Sigma-aldrich

- Pentamethyldiethylenetriamine, CAS No. 3030-47-5, 99%, Sigma-aldrich.

Preparation of mono-metallic catalyst via deposition-precipitation-reduction:

Pd/TiO ₂ (FJ-056-342)

A certain mass of TiO ₂ (P90, 1.9840 g) was weighed and added into a round bottom flask, then a certain volume of deionized water (140 mL) .

A certain mass of metal precursor H ₂PdCl ₄ (H ₂PdCl ₄ in diluted HCl aqueous solution, 0.025 g/mL ^-1, 1.51 mL) was weighed. (H ₂PdCl ₄ in diluted HCl aqueous solution was prepared by dissolving PdCl ₂ (0.1769 g) in 37% (v/v) HCl (0.53 mL) , then followed by water addition in order to dilute the solution to 10 mL, ChemSusChem 2013, 6, 1923–1930. )

The aqueous solution of metal precursor were added in to the flask containing TiO ₂ and deionized water, and the solution was stirred vigorously for several hours at room temperature.

A solution of 1mol/L NaOH was prepared with deionized water in advance. The sodium hydroxide solution was added to the previous reaction flask drop wise upon stirring, in order to adjust the pH to 10 (pH was measured by a calibrated pH meter) , then the solution was stirred vigorously for several hours at room temperature.

A certain mass of NaBH ₄ solid (0.1138g) was weighed in a beaker and was dissolved in deionized water (15 mL) . The sodium borohydride solution was then added into a round bottom flask sinking in an ice bath (at 0℃) and the afforded solution was stirred vigorously for several hours at 0℃. A grey (for Pd) milky solution was obtained.

The solution was transferred from the round bottom flask to the centrifuge tube for centrifugations (15000 rounds/minute) . The product was treated by repeating deionized water addition, centrifugation, wastewater pouring out, and pH measurement, until the pH became neutral (equal to 7) .

The afforded catalyst was transferred to a clean round bottom flask, heated and evaporated by using pump vacuum to dry deionized water at 80℃, and the dried catalyst was analyzed by TEM, ICP, UV-Vis spectra if needed, and stored in a sample bottle under argon.

Au/TiO ₂ (FJ-056-368)

A certain mass of metal precursor AuCl ₃·xH ₂O (Au 49 wt%in AuCl ₃·xH ₂O, 0.0165 g) was weighed and added into a round bottom flask.

A certain mass of TiO ₂ (P90, 0.9924 g) and a certain volume of deionized water (70 mL) were weighed and added into this round bottom flask.

A certain mass of NaBH ₄ solid (0.0307 g) was weighed in a beaker and was dissolved in deionized water (4 mL) . The sodium borohydride solution was then added into a round bottom flask sinking in an ice bath (at 0℃) and the afforded solution was stirred vigorously for several hours at 0℃. A purple milky solution was obtained.

Ag/TiO ₂ (FJ-056-369)

A certain mass of TiO ₂ (P90, 0.9939 g) was weighed and added into a round bottom flask, then a certain volume of deionized water (70 mL) .

A certain mass of metal precursor AgNO ₃ (0.0126 g) was weighed and added into this round bottom flask. The solution was stirred vigorously for several hours at room temperature.

A certain mass of NaBH ₄ solid (0.0565 g) was weighed in a beaker and was dissolved in deionized water (7 mL) . The sodium borohydride solution was then added into a round bottom flask sinking in an ice bath (at 0℃) and the afforded solution was stirred vigorously for several hours at 0℃. A light pink milky solution was obtained.

Preparation of mono-metallic catalyst by means of photo-deposition:

Pd/TiO ₂ (FJ-056-371)

A certain mass of TiO ₂ (P90, 0.4964 g) was weighed and added into a Schlenk flask under nitrogen atmosphere, then a certain volume of deionized water (3.5 mL) , isopropanol (4.5 mL) were added in turn.

A certain mass of metal precursor H ₂PdCl ₄ (H ₂PdCl ₄in diluted HCl aqueous solution, 0.025 g/mL ^-1, 0.38 mL) was weighed and then dissolved with deionized water, and a precursor solution was prepared. (H ₂PdCl ₄ was prepared by dissolving PdCl ₂ (0.1769 g) in 37% (v/v) HCl (0.53 mL) , then followed by water addition in order to dilute the solution to 10 mL. )

The aqueous solution of H ₂PdCl ₄ precursor were added in to the flask containing TiO ₂ and solvents, and the solution (concentration of H ₂PdCl ₄ precursor in the final reaction solution was 0.0107 mol/L) was protected using aluminum foil in order to avoid any light irradiation, and it was firstly put into a microwave machine for 30 minutes, then stirred vigorously at room temperature for 50 minutes.

This solution was then stirred at room temperature vigorously under UV (365 nm, 22 A, 308W) irradiation for 1 hour affording a dark-gray milky solution.

This solution in the Schlenk flask was then transferred to the centrifuge tube for centrifugations (15000 rounds/minute) . The product was treated by repeating deionized water addition, centrifugation, waste solution pouring out, and pH measurement, until the pH became neutral (equal to 7) . Totally this procedure was repeated for 20 times.

AP-056-370 was prepared in the same way except the precursor PdNO ₃-xH ₂O, and before UV irradiation, only 5 minutes microwave treatment and no previous stirring was launched.

AP-056-372 was prepared in the same way except the current of UV during photo-deposition was 13 A, 182W.

AP-056-373 was prepared in the same way except the current of UV during photo-deposition was 13 A, 182W, the added volume of deionized water (14 mL) , isopropanol (18 mL) were added and the concentration of H ₂PdCl ₄ precursor in the final reaction solution was 0.0027 mol/L, and the UV irradiation duration was 1.5 hours.

AP-056-432 was prepared in the same way except the current of UV during photo-deposition was 13 A, 182W, the catalyst was washed by isopropanol each time before centrifugation for 20 times.

AP-056-433 was prepared in the same way except the current of UV during photo-deposition was 13 A, 182W, the catalyst was washed by deionized water followed by centrifugation for 3 times.

AP-056-459 was prepared in the same way except the current of UV during photo-deposition was 13 A, 182W, the catalyst was washed by deionized water followed by centrifugation for 10 times.

AP-056-435, AP-056-436, AP-056-456 were prepared in the same way except the current of UV during photo-deposition was 13 A, 182W, the Pd loading was different; and except the UV irradiation duration for AP-056-436 was 2 hours.

AP-056-488 was prepared in the same way except the current of UV during photo-deposition was 13 A, 182W, the scale of the reaction was 4 times larger, the solution protected by aluminum foil was stirred vigorously at room temperature for 4 hours, and then irradiated by UV upon stirring for 3 hours.

AP-056-491 and AP-056-493 were prepared in the same way except the current of UV during photo-deposition was 13 A, 182W, the support was different, and the solution protected by aluminum foil was stirred vigorously at room temperature for 1.5 hours, and then irradiated by UV upon stirring for 2 hours.

Au/TiO ₂ (FJ-056-381)

A certain mass of TiO ₂ (P90, 0.4965 g) was weighed and added into a Schlenk flask under nitrogen atmosphere, then a certain volume of deionized water (3.5 mL) , isopropanol (4.5 mL) were added in turn.

A certain mass of metal precursor AuCl ₃·xH ₂O (Au 49 wt%in AuCl ₃·xH ₂O, 0.0084 g) was weighed and added in to the flask containing TiO ₂, and the solution was protected using aluminum foil in order to avoid any light irradiation, and it was stirred vigorously at room temperature for 1 hour.

This solution was then stirred at room temperature vigorously under UV (365 nm, 13 A, 182W) irradiation for 1 hour affording a purple milky solution.

This solution in the Schlenk flask was then transferred to the centrifuge tube for centrifugations (15000 rounds/minute) . The product was treated by repeating deionized water addition, centrifugation, waste solution pouring out, and pH measurement, until the pH became neutral (equal to 7) .

Ag/TiO ₂ (FJ-056-376)

A certain mass of metal precursor AgNO ₃ (0.0075 g) was weighed and added in to the flask containing TiO ₂, and the solution was protected using aluminum foil in order to avoid any light irradiation, and it was stirred vigorously at room temperature for 105 minutes.

This solution was then stirred at room temperature vigorously under UV (365 nm, 13 A, 182W) irradiation for 1 hour affording a deep-yellow to orange milky solution.

Preparation of bimetallic catalyst preparation via photo-deposition:

Au-Pd/TiO ₂ (FJ-056-458)

A certain mass of TiO ₂ (P90, 0.9834 g) was weighed and added into a Schlenk flask under nitrogen atmosphere.

Metal precursor AuCl ₃·xH ₂O (Au 49 wt%in AuCl ₃·xH ₂O, 0.01632 g) was weighed and dissolved in deionized water (7.0 mL) and isopropanol (9.0 mL) , and a precursor solution was prepared.

The metal precursor solution was then added in to the flask containing TiO ₂, and the solution was protected using aluminum foil in order to avoid any light irradiation, and it was stirred vigorously at room temperature for 2 hours.

This solution was then stirred at room temperature vigorously under UV (365 nm, 13 A, 182W) irradiation for 3 hours until a purple milky solution was obtained. UV irradiation was then switched off.

Under nitrogen atmosphere, then a H ₂PdCl ₄ precursor (H ₂PdCl ₄precursor in diluted HCl aqueous solution, 0.025 g/mL ^-1, 0.75 mL) was weighed and dissolved into the previous solution, and the solution was protected using aluminum foil in order to avoid any light irradiation, and it was stirred vigorously at room temperature for 2 hours; then stirred at room temperature vigorously under UV (365 nm, 13 A, 182W) irradiation for 3 hours until a purple-grey milky solution was obtained. (H ₂PdCl ₄ precursor was prepared by dissolving PdCl ₂ (0.1769 g) in 37% (v/v) HCl (0.53 mL) , then followed by water addition in order to dilute the solution to 10 mL) .

The solution in the Schlenk flask was then transferred to the centrifuge tube for centrifugations (15000 rounds/minute) . The product was treated by repeating deionized water or isopropanol addition, centrifugation, waste solution pouring out, and pH measurement, until the pH became neutral (equal to 7) . This catalyst was then transferred into a Schlenk flask again under nitrogen at room temperature.

Then another metal precursor was added via the procedure described above.

Pd-Au/TiO ₂ (FJ-056-471)

Metal precursor H ₂PdCl ₄ (H ₂PdCl ₄ precursor in diluted HCl aqueous solution, 0.025 g/mL ^-1, 0.75 mL) was weighed and dissolved in deionized water (7.0 mL) and isopropanol (9.0 mL) . (H ₂PdCl ₄ precursor was prepared by dissolving PdCl ₂ (0.1769 g) in 37% (v/v) HCl (0.53 mL) , then followed by water addition in order to dilute the solution to 10 mL) .

This solution was then stirred at room temperature vigorously under UV (365 nm, 13 A, 182W) irradiation for 3 hours until a grey milky solution was obtained. UV irradiation was then switched off.

Under nitrogen atmosphere, then a metal precursor AuCl ₃·xH ₂O (Au 49 wt%in AuCl ₃·xH ₂O, 0.01632 g) was weighed and added into the previous solution. The solution was protected using aluminum foil in order to avoid any light irradiation, and it was stirred vigorously at room temperature for 3 hours; then stirred at room temperature vigorously under UV (365 nm, 13 A, 182W) irradiation for 5 hours until a purple-grey milky solution was obtained.

Then another metal precursor was added via the procedure described above.

Pd-Au/TiO ₂ (FJ-056-470)

Metal precursors AuCl ₃·xH ₂O (Au 49 wt%in AuCl ₃·xH ₂O, 0.01680 g) and H ₂PdCl ₄ precursor (H ₂PdCl ₄in diluted HCl aqueous solution, 0.025 g/mL ^-1, 0.75 mL) were independently weighed and both dissolved in deionized water (7.0 mL) and isopropanol (9.0 mL) , and a precursor solution was prepared. (H ₂PdCl ₄ precursor was prepared by dissolving PdCl ₂ (0.1769 g) in 37% (v/v) HCl (0.53 mL) , then followed by water addition in order to dilute the solution to 10 mL) .

The metal precursor solution was then added in to the flask containing TiO ₂, and the solution was protected using aluminum foil in order to avoid any light irradiation, and it was stirred vigorously at room temperature for 3 hours.

This solution was then stirred at room temperature vigorously under UV (365 nm, 13 A, 182W) irradiation for 7 hours until a purple milky solution was obtained.

Then another metal precursor was added via the procedure described above.

Table 1 ICP results

Analytical equipment information:

Perkin Elmer ICP-OES 8000

Electric balance with 0.0001g precision

CEM 6 microwave oven

IKA heating plate

1 mL transfer pipette

100 μL transfer pipette

50ml ICP tube

Software of ICP: Winlab32 for ICP Version 5.4.0.0687

Analytical conditions:

- Preparation: Weigh 50mg sample, add 3ml H ₃PO ₄ and 3ml H ₂SO ₄, heat at 280C with heating plate, until sample totally dissolved, when the solution left until 3-4 ml, dilute with DI water and add 10ppm Sc as an internal standard solution to 50ml. Then dilute 10 times to test high concentration elements.

- Reagents and Solution: Distilled de-ionized Ultra High Quality (UHQ chemical resistivity: 18MΩcm ^-1) water (Millipore) , Phosphoric acid, AR grade, 85%, Sulfuric acid, AR grade, 98%ICP multi-element standard solution IV, Merck

- Instrument setting: Perkin Elemer 8000 ICP-OES was used for the determination of three elements. The operation parameters of ICP-OES were set as recommended by the manufacturer. The ICP-OES operating conditions are listed in Table 2.

Table 2 ICP operating parameters

Example 1:

An autoclave equipped with a quartz window containing a clean vial made in quartz equipped with a 6mm * 20mm cylindrical PTFE magnetic stirrer was charged under nitrogen after vacuum & nitrogen exchanges for 3 times, then the photocatalysts prepared via different methods described in Table 3 were weighed (0.02g) and then transferred into the quartz vial immediately, followed by the additions of methanol (0.06 mol, 2.0 g) and octylamine (0.2 mmol, 0.026 g) under nitrogen subsequently.

The autoclave was well sealed under nitrogen, and purged by nitrogen 1 atm and fast evacuated for 3 times, finally purged with 5 bar of hydrogen. The sealing of the reactor is checked by waiting 1 hour at room temperature without stirring, and if the pressure remains unchanged then the reactor is well sealed.

Then the window of the autoclave was connected with a UV lamp equipped with a 365 nm filter. The autoclave equipped with a recycling water-cooling bath was put on a magnetic stirring plate. Upon stirring, the UV lamp was switched on with 13A of current, 182W of power, then the reaction was proceeded for 2 hours at ambient temperature. The equipment was then cooled down and switched off, and the hydrogen gas was evacuated carefully in the fume hood. To the reaction mixture was added internal standard bisphenyl with accurate weight. After complete dissolving of bisphenyl, the liquid was firstly weighed and then filtered and analyzed by GC. The conversion and yields were calculated using internal standard calibration.

Table 3

OA-Octylamine DMOA-Dimethyloctylamine MOA-Methyloctylamine

Method 1: Deposition-precipitation-reduction method; Method 2: Photo-deposition method

Example 2:

An autoclave equipped with a quartz window containing a clean vial made in quartz equipped with a 6mm * 20mm cylindrical PTFE magnetic stirrer was charged under nitrogen after vacuum & nitrogen exchanges for 3 times, then the photo-catalysts prepared via photo-deposition method using different intensity of UV light described in Table 4 were weighed (0.02g) and then transferred into the quartz vial immediately, followed by the additions of methanol (0.06 mol, 2.0 g) and octylamine (0.2 mmol, 0.026 g) under nitrogen subsequently.

Table 4

OA-Octylamine DMOA-Dimethyloctylamine MOA-Methyloctylamine

Example 3:

The catalysts were prepared using different concentrations of palladium precursor described in Table 5.

An autoclave equipped with a quartz window containing a clean vial made in quartz equipped with a 6mm * 20mm cylindrical PTFE magnetic stirrer was charged under nitrogen after vacuum&nitrogen exchanges for 3 times, then the photocatalysts prepared via photo-deposition method were weighed (0.02g) and then transferred into the quartz vial immediately, followed by the additions of methanol (0.06 mol, 2.0 g) and octylamine (0.2 mmol, 0.026 g) under nitrogen subsequently.

Table 5

OA-Octylamine DMOA-Dimethyloctylamine MOA-Methyloctylamine

Example 4:

The catalysts after preparation was washed via centrifugation using different solvent after different times of washing described in Table 6.

An autoclave equipped with a quartz window containing a clean vial made in quartz equipped with a 6mm * 20mm cylindrical PTFE magnetic stirrer was charged under nitrogen after vacuum & nitrogen exchanges for 3 times, then the photocatalysts prepared via photo-deposition method were weighed (0.02g) and then transferred into the quartz vial immediately, followed by the additions of methanol (0.06 mol, 2.0 g) and octylamine (0.2 mmol, 0.026 g) under nitrogen subsequently.

Table 6

OA-Octylamine DMOA-Dimethyloctylamine MOA-Methyloctylamine

DI: Deionized

Example 5:

An autoclave equipped with a quartz window containing a clean vial made in quartz equipped with a 6mm * 20mm cylindrical PTFE magnetic stirrer was charged under nitrogen after vacuum & nitrogen exchanges for 3 times, then the photocatalysts prepared via photo-deposition method with different palladium loading described in Table 7 were weighed (0.02g) and then transferred into the quartz vial immediately, followed by the additions of methanol (0.06 mol, 2.0 g) and octylamine (0.2 mmol, 0.026 g) under nitrogen subsequently.

Table 7

OA-Octylamine DMOA-Dimethyloctylamine MOA-Methyloctylamine

Example 6:

An autoclave equipped with a quartz window containing a clean vial made in quartz equipped with a 6mm * 20mm cylindrical PTFE magnetic stirrer was charged under nitrogen after vacuum & nitrogen exchanges for 3 times, then the photocatalysts prepared via photo-deposition method using different supports described in Table 8 were weighed (0.02g) and then transferred into the quartz vial immediately, followed by the additions of methanol (0.06 mol, 2.0 g) and octylamine (0.2 mmol, 0.026 g) under nitrogen subsequently.

Table 8

OA-Octylamine DMOA-Dimethyloctylamine MOA-Methyloctylamine

Example 7:

An autoclave equipped with a quartz window containing a clean vial made in quartz equipped with a 6mm * 20mm cylindrical PTFE magnetic stirrer was charged under nitrogen after vacuum & nitrogen exchanges for 3 times, then the photocatalysts prepared via photo-deposition method using different combination of metallic precursors and affording different bimetallic catalysts described in Table 9 were weighed (0.02g) and then transferred into the quartz vial immediately, followed by the additions of methanol (0.06 mol, 2.0 g) and octylamine (0.2 mmol, 0.026 g) under nitrogen subsequently.

Table 9

OA-Octylamine DMOA-Dimethyloctylamine MOA-Methyloctylamine

Example 8:

An autoclave equipped with a quartz window containing a clean vial made in quartz equipped with a 6mm*20mm cylindrical PTFE magnetic stirrer was charged under nitrogen after vacuum&nitrogen exchanges for 3 times, then the photocatalysts prepared via photo-deposition method were weighed (0.02g) and then transferred into the quartz vial immediately, followed by the additions of methanol (0.06 mol, 2.0 g) and octylamine (0.2 mmol, 0.026 g) under nitrogen subsequently.

The autoclave was well sealed under nitrogen, and purged by nitrogen 1 atm and fast evacuated for 3 times, finally purged with different pressures of hydrogen described in Table 10. The sealing of the reactor is checked by waiting 1 hour at room temperature without stirring, and if the pressure remains unchanged then the reactor is well sealed.

Table 10

OA-Octylamine DMOA-Dimethyloctylamine MOA-Methyloctylamine

Example 9:

An autoclave equipped with a quartz window containing a clean vial made in quartz equipped with a 6mm * 20mm cylindrical PTFE magnetic stirrer was charged under nitrogen after vacuum & nitrogen exchanges for 3 times, then the photocatalysts prepared via photo-deposition method were weighed (0.02g) and then transferred into the quartz vial immediately, followed by the additions of methanol (0.06 mol, 2.0 g) and octylamine with different weight according to different mass ratio of catalyst to octylamine described in Table 11, under nitrogen subsequently.

The autoclave was well sealed under nitrogen, and purged by nitrogen 1 atm and fast evacuated for 3 times, finally purged with with 5 bar of hydrogen. The sealing of the reactor is checked by waiting 1 hour at room temperature without stirring, and if the pressure remains unchanged then the reactor is well sealed.

Table 11

OA-Octylamine DMOA-Dimethyloctylamine MOA-Methyloctylamine

Example 10:

Then the window of the autoclave was connected with a UV lamp equipped with a 365 nm filter. The autoclave equipped with a recycling water-cooling bath was put on a magnetic stirring plate. Upon stirring, the UV lamp was switched on with a certain current and power described in Table 12, then the reaction was proceeded for 2 hours at ambient temperature. The equipment was then cooled down and switched off, and the hydrogen gas was evacuated carefully in the fume hood. To the reaction mixture was added internal standard bisphenyl with accurate weight. After complete dissolving of bisphenyl, the liquid was firstly weighed and then filtered and analyzed by GC. The conversion and yields were calculated using internal standard calibration.

Table 12

OA-Octylamine DMOA-Dimethyloctylamine MOA-Methyloctylamine

Example 11:

A Schlenck type reactor made in glass with a screwed stopper equipped with a cylindrical PTFE magnetic stirrer was charged under nitrogen after vacuum&nitrogen exchanges for 3 times, then the photocatalysts prepared via photo-deposition method were weighed (0.02g) and then transferred into the quartz vial immediately, followed by the additions of methanol (0.06 mol, 2.0 g) and octylamine (0.2 mmol, 0.026 g) under nitrogen subsequently.

The reactor was well sealed under nitrogen, and purged by argon 1 atm for 1 minute, finally purged with 1 atmosphere of hydrogen. The reactor is sealed at room temperature without stirring.

The reactor equipped without a recycling water-cooling bath was put on a magnetic stirring plate. Then the reactor was irradiated with a UV lamp without a 365 nm filter. Upon stirring, the UV lamp was switched on with 9W power, then the reaction was proceeded for a certain time duration described in Table 13 at ambient temperature. The equipment was then cooled down and switched off, and the hydrogen gas was evacuated carefully in the fume hood. To the reaction mixture was added internal standard bisphenyl with accurate weight. After complete dissolving of bisphenyl, the liquid was firstly weighed and then filtered and analyzed by GC. The conversion and yields were calculated using internal standard calibration.

Table 13

OA-Octylamine DMOA-Dimethyloctylamine MOA-Methyloctylamine

Example 12:

An autoclave equipped with a quartz window containing a clean vial made in quartz equipped with a 6mm*20mm cylindrical PTFE magnetic stirrer was charged under nitrogen after vacuum&nitrogen exchanges for 3 times, then the photocatalysts prepared via photo-deposition method 0.55wt%Pd/TiO ₂ (P90) were weighed (0.026g) and then transferred into the quartz vial immediately, followed by the additions of methanol (0.06 mol, 2.0 g) and diethylenetriamine (DETA) (0.25 mmol, 0.026 g) , under nitrogen subsequently.

Then the window of the autoclave was connected with a UV lamp equipped with a 365 nm filter. The autoclave equipped with a recycling water-cooling bath was put on a magnetic stirring plate. Upon stirring, the UV lamp was switched on with 18A of current, 252W of power, then the reaction was proceeded for 40 hours at ambient temperature. The equipment was then cooled down and switched off, and the hydrogen gas was evacuated carefully in the fume hood. To the reaction mixture was added internal standard bisphenyl with accurate weight. After complete dissolving of bisphenyl, the liquid was firstly weighed and then filtered and analyzed by GC. The conversion and yields were calculated using internal standard calibration. The conversion of DETA is 98%. The yield of N, N, N', N” , N” -pentamethyldiethylenetriamine (PMDTA) is 60%.

Comparative Example:

The autoclave was well sealed under nitrogen, and purged by nitrogen 1 atm and fast evacuated for 3 times, finally purged with different pressures of hydrogen versus argon described in Table 14. The sealing of the reactor is checked by waiting 1 hour at room temperature without stirring, and if the pressure remains unchanged then the reactor is well sealed.

It is shown in the table that higher OA conversion and alkylated amines were obtained by using hydrogen as working atmosphere.

Table 14

OA-Octylamine DMOA-Dimethyloctylamine MOA-Methyloctylamine

Claims

A method for preparing an alkylated amine by reacting a primary or secondary amine with an alcohol in the presence of hydrogen, a metal catalyst supported by photosensitive titanium oxide, and UV irradiation.
The method according to claim 1, wherein the primary or secondary amine has the general formula (I) :

R ¹R ²NH (I)

wherein R ¹ and R ², independently from each other, represent hydrogen, or a straight, branched or cyclic hydrocarbon group, which is optionally interrupted by one or several heteroatoms and/or which is optionally substituted by one or several functional groups, R ¹ and R ² are not both hydrogen at the same time, and heteroatoms is O, S, F, or N.
The method according to claim 1, wherein the primary or secondary amine has the general formula (II) :

wherein:

- n is an integer between 0 and 20;

- m is an integer between 1 and 3;

- p is an integer between 0 and 2, and

- p+m=3.
The method according to claim 3, wherein the compound having the general formula (II) is a compound having general formula (III) , (IV) or (V) :

wherein n is an integer between 0 and 20.
The method according to claim 3 or 4, wherein the compound having the general formula (II) is selected from the group consisting of dimethylenetriamine, diethylenetriamine, dipropylenetriamine, dibutylenetriamine, dipentylenetriamine, dihexylenetriamine, diheptylenetriamine, dioctylenetriamine, dinonylenetriamine, didecylenetriamine, methylenediamine, ethylenediamine, propylenediamine, butylenediamine, pentylenediamine, hexylenediamine, heptylenediamine, octylenediamine, nonylenediamine, and decylenediamine, triaminomethylamine, tris (2-aminoethyl) amine, tris (3-aminopropyl) amine, tris (4-aminobutyl) amine, tris (5-aminopentyl) amine, tris (6-aminohexyl) amine, tris (7-aminoheptyl) amine, tris (8-aminooctyl) amine, tris (9-aminononyl) amine and tris (10-aminodecyl) amine.
The method according to claim 1, wherein the alcohol has the general formula (VI) :

R ³OH (VI)

wherein R ³ is an alkyl, an alkenyl or an alkynyl.
The method according to any one of claims 1 to 6, wherein the metal catalyst comprises a noble metal selected from the group consisting of palladium, gold, platinum, silver and combinations thereof.
The method according to any one of claims 1 to 7, wherein photosensitive titanium oxide is a mixture of anatase type and rutile type crystals.
The method according to any one of claims 1 to 8, wherein the BET surface area of crystals of photosensitive titanium oxide is preferably from 10 to 600 m ²/g and preferably from 30 to 400 m ²/g.
The method according to any one of claims 1 to 9, wherein the weight ratio of the supported metal catalyst to the primary or secondary amine is from 0.001 to 100 and preferably from 0.01 to 10.
The method according to any one of claims 1 to 10, wherein the weight ratio of the primary or secondary amine to the alcohol is from 0.0001 to 0.5 and preferably from 0.001 to 0.2.
The method according to any one of claims 1 to 11, wherein the reaction is carried out in the presence of a solvent and the concentration of the primary or secondary amine in the solvent is from 0.01 wt%to 50wt%and preferably from 0.1wt%to 20wt%.
The method according to any one of claims 1 to 12, wherein the reaction is carried out under a hydrogen pressure in a range of 0.1 to 20 bar, and preferably 0.5 to 12 bar.
The method according to any one of claims 1 to 13, wherein the reaction temperature is from 0℃ to 100℃, preferably from 10℃ to 50℃ and more preferably room temperature.
A mixture comprising:

(i) A primary or secondary amine,

(ii) An alcohol,

(iii) Hydrogen, and

(iv) A metal catalyst supported by photosensitive titanium oxide.