(2006.0 1) (21) International Application Number: PCT/EP20 18/083 934 (22) International Filing Date: 07 December 2018 (07

(

(51) International Patent Classification: C07F 5/00 (2006.0 1) C07F 5/06 (2006.0 1) (21) International Application Number: PCT/EP20 18/083 934 (22) International Filing Date: 07 December 2018 (07. 12.2018) (25) Filing Language: English (26) Publication Language: English (30) Priority Data: 17207086.4 13 December 2017 (13. 12.2017) EP (71) Applicant: AKZO NOBEL CHEMICALS INTER¬ NATIONAL B.V. [NL/NL]; Velperweg 76, 6824 BM Arn¬ hem (NL). (72) Inventors: TE NIJENHUIS, Marcellinus Antonius Maria; Het Boschloo 12, 7232 GK Warnsveld (NL). WOUDENBERG, Richard Herman; Stijne van Sallandt- straat 58, 743 1 GS Diepenveen (NL). (74) Agent: AKZO NOBEL CHEMICALS IP GROUP; Velperweg 76, 6824 BM Arnhem (NL). (81) Designated States (unless otherwise indicated, for every kind of national protection available) : AE, AG, AL, AM, AO, AT, AU, AZ, BA, BB, BG, BH, BN, BR, BW, BY, BZ, CA, CH, CL, CN, CO, CR, CU, CZ, DE, DJ, DK, DM, DO, DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT, HN, HR, HU, ID, IL, IN, IR, IS, JO, JP, KE, KG, KH, KN, KP, KR, KW, KZ, LA, LC, LK, LR, LS, LU, LY, MA, MD, ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI, NO, NZ, OM, PA, PE, PG, PH, PL, PT, QA, RO, RS, RU, RW, SA, SC, SD, SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN, TR, TT, TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW. (84) Designated States (unless otherwise indicated, for every kind of regional protection available) : ARIPO (BW, GH, GM, KE, LR, LS, MW, MZ, NA, RW, SD, SL, ST, SZ, TZ, UG, ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, RU, TJ, TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, LV, MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK, SM, TR), OAPI (BF, BJ, CF, CG, Cl, CM, GA, GN, GQ, GW, KM, ML, MR, NE, SN, TD, TG).

Published: — with international search report (Art. 21(3))

(54) Title: PROCESS FOR PURIFICATION OF DIMETHYL ALUMINIUM CHLORIDE (57) Abstract: Process for the removal of gallium compounds from dimethyl aluminium chloride (DMAC)-containing compositions, comprising the steps of: (i) adding methyl aluminium sesquichloride (MASC) to said DMAC-containing composition, thereby forming dimethyl aluminium chloride (DMAC) and methyl gallium chloride (MexGaCI(3_x , wherein x= 1or 2), (ii) reducing said methyl gallium chloride with metallic aluminium to form methyl aluminium dichloride (MADC) and metallic gallium, and (iii) removing metallic gallium from the DMAC-containing composition. PROCESS FOR PURIFICATION OF DIMETHYL ALUMINIUM CHLORIDE

The present invention relates to a process for the removal of gallium compounds from dimethyl aluminium chloride-containing compositions, a process for producing trimethyl gallium and purified dimethyl aluminium chloride, and a process for the production of trimethyl aluminium using said purified dimethyl aluminium chloride.

With the advancement of mobile phones and optical communication technologies, demand is rapidly growing for compound semiconductors for use in high speed electronic devices such as high electron mobility transistors (HEMTs), heterojunction bipolar transistors (HBTs), semiconductor lasers, optical devices such as white and blue super high-intensity LEDs, and other applications. In general, alkyl derivatives of group 12 and group 13 metals, and in particular the methyl or ethyl derivatives, are often used as metalorganic precursors for compound semiconductors. A great demand exists for, in particular, trimethyl gallium for the production of compound semiconductors by MOCVD with group 15 elements, such as nitrogen, arsenic, and the like.

Trimethyl gallium (TMG) is conventionally prepared by reacting gallium trichloride with trimethyl aluminium (TMAL). According to this reaction, the production of one mole of TMG requires the use of 3 moles of TMAL:

→ GaC + 3 AI(CH 3)S Ga(CH 3)3 + 3 AI(CH 3)2C I

The resulting TMG is isolated by distillation.

Documents disclosing TMG production are WO 2012/083450, WO 2013/083449,

US 2006/0471 32, and JP-A 2006-3421 0 1. TMAL is considerably more expensive than other alkyl aluminum compounds, such as triethyl aluminium and dimethyl aluminium chloride. With three moles of TMAL being required for the production of only one mole of TMG, it will be clear that the TMG production costs are heavily determined by the TMAL price.

A by-product of this TMG production process is dimethyl aluminium chloride (DMAC). DMAC can be used to make TMAL, according to the following reaction:

→ 3 (CH 3)2AICI + 3 Na 2 (CH3)3A I + 3 NaCI + Al

Using the by-product DMAC for the production of TMAL would reduce the TMAL price, and, hence the TMG production costs.

Unfortunately, however, DMAC ends up in the distillation residue, which also contains residual TMG, while for its use in the production of TMAL, DMAC should be free (which means: containing less than 5 ppm) of gallium compounds. Otherwise, the resulting TMAL becomes polluted with gallium compounds. However, removal of gallium to such an extent is not possible with distillation or other known purification methods.

An object of the present invention is, therefore, the provision of a process for obtaining Ga-free DMAC from the TMG distillation residue. A further object is the provision of TMAL using said Ga-free DMAC. An additional object the provision of a process for the production of TMG and Ga- free DMAC. In a first embodiment, the present invention relates to a process for the removal of gallium compounds from dimethyl aluminium chloride (DMAC)-containing compositions, comprising the steps of: adding methyl aluminium sesquichloride (MASC) to said DMAC-containing composition, thereby forming dimethyl aluminium chloride (DMAC) and

is in methyl gallium chloride (MexGaCI(3-X) , wherein x an average value the range 1-2), reducing said methyl gallium chloride with metallic aluminium to form methyl aluminium dichloride (MADC) and metallic gallium, and - removing said metallic gallium from the DMAC-containing composition.

The first step of this process involves the addition of methyl aluminium sesquichloride (MASC) - (C A Cl - to the DMAC-containing composition. A preferred DMAC-containing composition is the distillation residue (bottoms) of a trimethyl gallium (TMG) production process.

MASC reacts with the TMG to form DMAC and methyl gallium chloride:

→ -x x (CH3)3A I2Cl3 + (CH 3)3Ga 2x (CH3)2AICI + (CH3)(3 )GaCl x wherein x is an average value in the range 1 to 2 .

If the DMAC-containing composition also contains trimethyl aluminium (TMAL), as in the distillation residue (bottoms) of a trimethyl gallium (TMG) production process, MASC also reacts with TMAL to produce even more DMAC: → (CH3)3A I2C I3 + (CH 3)3A I 3 (CH3) AICI

The first step of the process of the first embodiment is preferably conducted under inert (e.g. nitrogen) atmosphere and at a temperature in the range -20 to 200°C, more preferably 0-100°C, even more preferably 20-70°C, and most preferably 20- 50°C. MASC is preferably added to the DMAC-containing composition in an amount ranging from equimolar up to a 20-fold molar excess, more preferably up to a 10- fold molar excess, even more preferably up to a 7-fold molar excess, and most preferably up to a 4-fold molar excess, based on the total molar amount of gallium compounds (calculated as Ga) and TMAL in the DMAC-containing composition. The amount of Ga compound (calculated as Ga) can be determined with ICP and the level of TMAL can be determined by 1H-NMR.

MASC can be added in pure form or dissolved in a solvent. Examples are suitable solvents are saturated aliphatic hydrocarbons like pentane, hexane, heptane, octane, nonane, decane, undecane, and dodecane; saturated alicyclic hydrocarbons like cyclohexane and cycloheptane; and aromatic hydrocarbons like toluene, xylene, trimethylbenzene, ethylbenzene, ethyltoluene, and indene.

The second step of the process of the first embodiment involves the reduction of the formed methyl gallium chloride with metallic aluminium to form dimethyl aluminium chloride (DMAC) and/or methyl aluminium dichloride (MADC) and metallic gallium:

→ (CH3)GaCI2 + Al (CH3)AICI2 + Ga → (CH3)2GaCI + Al (CH3)2AICI + Ga

The metallic aluminium required for this step is preferably added to the DMAC- containing composition in powder form, either before addition of the MASC, after addition of the MASC, or at the same time (e.g. in admixture with MASC).

The metallic aluminium can be added in stoichiometric amounts relative to Ga. It is, however, preferred to add the aluminium in excess, preferably up to a 100-fold excess, preferably up to a 20-fold excess, more preferably up to a 10-fold excess, and most preferably up to a 5-fold excess, relative to Ga. This second step is preferably conducted under inert (e.g. nitrogen) atmosphere and at a temperature in the range -20 to 200°C, more preferably 0-100°C, even more preferably 20-70°C, and most preferably 20-50°C. Preferably, the process is conducted as a one pot process, wherein the first and the second step occur simultaneously in the same reactor.

The formed metallic gallium separates from the reaction mixture and forms an alloy with excess metallic aluminium. The metallic gallium can be removed from the reaction mixture by conventional separation methods, such as distillation, filtration, or decantation. The resulting reaction mixture is free, i.e. contains less than 5 ppm, of dissolved gallium compounds.

In a second embodiment, the present invention relates to a process for the preparation trimethyl gallium (TMG) and dimethyl aluminium chloride (DMAC) comprising the steps of:

reacting trimethyl aluminium (TMAL) with GaCI3 to form trimethyl gallium (TMG) and dimethyl aluminium chloride (DMAC), isolating trimethyl gallium (TMG) from the reaction mixture by distillation, - adding methyl aluminium sesquichloride (MASC) to the residue of said distillation, thereby forming dimethyl aluminium chloride (DMAC) and methyl is an in gallium chloride (MexGaCI(3-X) , wherein x average value the range 1- 2), reducing said methyl gallium chloride with metallic aluminium to form methyl aluminium dichloride (MADC) and metallic gallium, and removing said metallic gallium from the DMAC-containing composition.

The first step of the process of this second embodiment is preferably conducted under inert (e.g. nitrogen) atmosphere at a temperature in the range 0-280°C, preferably 25-250°C, most preferably 50-1 75°C. The temperature can be kept constant during the reaction, but may also gradually rise. The reaction can be performed at atmospheric pressure or lower pressures. At lower pressures, lower temperatures may be applied.

The reaction between TMAL and GaCI3 is carried out by introducing the GaCh and the trimethyl aluminium (TMAL), and optionally a solvent, into a reaction vessel under inert gas atmosphere. These compounds can be added in any form and in any order. Gallium trichloride, which is solid under the addition conditions may be added as such, but may also be added to the reactor dissolved in a solvent or in molten form. Addition as solution is especially preferred if the process is conducted in continuous manner. Examples of suitable solvents are saturated aliphatic hydrocarbons like pentane, hexane, heptane, octane, nonane, decane, undecane, and dodecane; saturated alicyclic hydrocarbons like cyclohexane and cycloheptane; and aromatic hydrocarbons like toluene, xylene, trimethylbenzene, ethylbenzene, ethyltoluene, and indene. Preferred solvents are those that are easily separable from the resulting TMG, more preferably by having a boiling point that differs significantly from that of TMG.

TMAL is preferably added to the GaCh in a slight excess compared to the theoretical molar ratio of 3:1 .

This excess is preferably 0-10 mol%, more preferably 0-5 mol%, and most preferably at most 0-3 mol%. The molar ratio TMAL : GaCh is therefore preferably

3.0:1 - 3.3:1 , more preferably 3.0:1 - 3.2:1 , and most preferably 3.0:1 - 3.1 : 1 .

The TMG is isolated from the reaction mixture by distillation (optionally under vacuum) and can be suitably used for the preparation of semiconductor devices, e.g. gallium nitride-based semiconductors. The destination residue is then treated according to the process of the first embodiment in order to obtain Ga-free DMAC.

In a third embodiment, the present invention relates to a process for the production of trimethyl aluminium (TMAL) comprising the steps of: removing gallium compounds from dimethyl aluminium chloride (DMAC)- containing compositions according to the process described above, reacting the resulting dimethyl aluminium chloride (DMAC) with sodium in an inert oil at a temperature in the range 100-150°C, and - isolating TMAL by evaporation.

The reaction between sodium and DMAC is performed in an inert, high boiling oil, which allows the sodium to be in liquid form and the formed NaCI and Al to remain suspended. The reaction is conducted under inert atmosphere. Examples of suitable oils include high boiling aliphatic hydrocarbons (boiling point above 150°C).

EXAMPLES

Example 1

352 g (2.0 mol, 1.0 eq.) of GaCI3 (ex MCP) were poured into a 1 I two-neck round- bottom flask equipped with a distillation column, stirrer and a thermocouple. 447 g

(6.2 mol, 3.1 eq.) TMAL were added dropwise to GaC . The mixture was gradually heated to reflux temperature. The distillate was collected into a cooled receiving flask (-5°C) with a top temperature of 56-58°C. TMG was isolated in a 90% yield (206 gram) with a purity of >99% based on 1H NMR analysis. The distillation residue contained DMAC and gallium compound(s). 75.5 gram MASC and 7.5 gram aluminum powder were charged to a 1 liter double walled reactor equipped with a mechanical stirrer. The reaction mixture was stirred and heated to 40°C. At 40°C, 150.5 gram of the above-mentioned distillation residue was dosed within 25 minutes. The resulting mixture was kept at 40°C for 6 hours. Insoluble gallium that was formed during the reaction was removed from the reaction mixture by filtration. 1H-NMR analysis indicated that the resulting filtrate did not contain any gallium compounds.

Comparative Example A Example 1 was repeated, except that 19.4 gram aluminium powder were mixed with the distillation residue, no MASC was added, and the reaction mixture was heated at 50°C for almost 2 days. Insoluble gallium that was formed during the reaction was removed from the reaction mixture by filtration. 1H-NMR analysis indicated that the resulting filtrate still contained 0.1 wt.% soluble Ga. CLAIMS

1. Process for the removal of gallium compounds from dimethyl aluminium chloride (DMAC)-containing compositions, comprising the steps of: - adding methyl aluminium sesquichloride (MASC) to said DMAC- containing composition, thereby forming dimethyl aluminium chloride is an (DMAC) and methyl gallium chloride (MexGaCI(3-X), wherein x average value in the range 1-2), reducing said methyl gallium chloride with metallic aluminium to form methyl aluminium dichloride (MADC) and metallic gallium, and removing said metallic gallium from the DMAC-containing composition.

2 . Process according to claim 1 wherein a mixture of metallic aluminium and methyl aluminium sesquichloride (MASC) is added to the DMAC-containing composition.

3 . Process according to claim 1 wherein first metallic aluminium is added to the DMAC-containing composition, followed by the addition of methyl aluminium sesquichloride (MASC).

4 . Process according to claim 1 wherein first methyl aluminium sesquichloride (MASC) is added to the DMAC-containing composition, followed by the addition of metallic aluminium

5 . Process according to any one of the preceding claims wherein the process is conducted at a temperature in the range -20 to 200°C, preferably 0-100°C, more preferably 20-70°C, and most preferably 20-50°C. 6 . Process according to any one of the preceding claims wherein MASC is added to the DMAC-containing composition in an amount ranging from equimolar up to a 20-fold molar excess, preferably up to a 10- fold molar excess, more preferably up to a 7-fold molar excess, and most preferably up to a 4-fold molar excess, based on the total molar amount of gallium

compounds (calculated as Ga) and trimethyl aluminium (TMAL) in the DMAC-containing composition.

7 . Process according to any one of the preceding claims wherein metallic

aluminium is added to the DMAC-containing composition in an amount ranging from equimolar up to a 100-fold excess, preferably up to a 20-fold excess, more preferably up to a 10-fold excess, and most preferably up to a 5-fold excess, relative to Ga.

8 . Process for the preparation trimethyl gallium (TMG) and dimethyl aluminium chloride (DMAC) comprising the steps of:

reacting trimethyl aluminium (TMAL) with GaCI3 to form trimethyl gallium (TMG) and dimethyl aluminium chloride (DMAC), - isolating trimethyl gallium (TMG) from the reaction mixture by distillation, - adding methyl aluminium sesquichloride (MASC) to the residue of said distillation, thereby forming dimethyl aluminium chloride (DMAC) and

is an in methyl gallium chloride (MexGaCI (3-X) , wherein x average value the range 1-2), reducing said methyl gallium chloride with metallic aluminium to form methyl aluminium dichloride (MADC) and metallic gallium, and removing said metallic gallium from the DMAC-containing composition. 9 . Process according to claim 8 wherein the reaction between trimethyl

aluminium (TMAL) and GaCI3 is conducted at a temperature in the range 0- 280°C, preferably 25-250°C, most preferably 50-1 75°C.

10. Process according to claim 8 or 9 wherein trimethyl aluminium (TMAL) and

GaC are reacted in a molar ratio TMAL : GaCI3 in the range 3.0:1 - 3.3:1 , preferably in the range 3.0:1 - 3.2:1 , and most preferably in the range 3.0:1 -

3.1 : 1 .

11. Process for the production of trimethyl aluminium (TMAL) comprising the steps of: removing gallium compounds from dimethyl aluminium chloride (DMAC)- containing compositions according to the process of claim 1, reacting the resulting dimethyl aluminium chloride (DMAC) with sodium in an inert oil at a temperature in the range 100-150°C, and isolating TMAL by evaporation.

12. Process according to claim 11, wherein the inert oil is an aliphatic hydrocarbon with a boiling point above 150°C. INTERNATIONAL SEARCH REPORT International application No PCT/EP2018/083934

A. CLASSIFICATION OF SUBJECT MATTER INV. C07F5/00 C07F5/06 ADD.

According to International Patent Classification (IPC) or to both national classification and IPC

B. FIELDS SEARCHED Minimum documentation searched (classification system followed by classification symbols) C07F

Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched

Electronic data base consulted during the international search (name of data base and, where practicable, search terms used) EPO-Internal

* Special categories of cited documents : "T" later document published after the international filing date or priority date and not in conflict with the application but cited to understand "A" document defining the general state of the art which is not considered the principle or theory underlying the invention to be of particular relevance Έ " earlier application or patent but published on or after the international "X" document of particular relevance; the claimed invention cannot be filing date considered novel or cannot be considered to involve an inventive "L" document which may throw doubts on priority claim(s) orwhich is step when the document is taken alone

rnational search report

Form PCT/ISA/210 (second sheet) (April 2005) INTERNATIONAL SEARCH REPORT International application No PCT/EP2018/083934

Form PCT/ISA/210 (continuation of second sheet) (April 2005) INTERNATIONAL SEARCH REPORT International application No Information on patent family members PCT/EP2018/083934

Patent document Publication Patent family Publication cited in search report date member(s) date

WO 2013083450 A1 13-06-2013 CN 103958528 A 30-07-2014 CN 103958529 A 30-07-2014 CN 107021973 A 08-08-2017 CN 108341834 A 31-07-2018 EP 2785724 A1 08-10-2014 EP 2785725 A1 08-10-2014 J P 6165159 B2 19-07-2017 J P 6165160 B2 19-07-2017 J P 2014534256 A 18-12-2014 J P 2015504439 A 12-02-2015 J P 2017105848 A 15-06-2017 J P 2017132788 A 03-08-2017 KR 20140099862 A 13-08-2014 KR 20140099863 A 13-08-2014 RU 2014126212 A 27-01-2016 RU 2014126213 A 27-01-2016 T W 201329091 A 16-07-2013 T W 201720834 A 16-06-2017 US 2014256974 A1 11-09-2014 US 2014287141 A1 25-09-2014 WO 2013083449 A1 13-06-2013 WO 2013083450 A1 13-06-2013

WO 2013083449 A1 13-06-2013 CN 103958528 A 30-07-2014 CN 103958529 A 30-07-2014 CN 107021973 A 08-08-2017 CN 108341834 A 31-07-2018 EP 2785724 A1 08-10-2014 EP 2785725 A1 08-10-2014 J P 6165159 B2 19-07-2017 J P 6165160 B2 19-07-2017 J P 2014534256 A 18-12-2014 J P 2015504439 A 12-02-2015 J P 2017105848 A 15-06-2017 J P 2017132788 A 03-08-2017 KR 20140099862 A 13-08-2014 KR 20140099863 A 13-08-2014 RU 2014126212 A 27-01-2016 RU 2014126213 A 27-01-2016 T W 201329091 A 16-07-2013 T W 201720834 A 16-06-2017 US 2014256974 A1 11-09-2014 US 2014287141 A1 25-09-2014 WO 2013083449 A1 13-06-2013 WO 2013083450 A1 13-06-2013

US 2006047132 A1 02-03-2006 CN 1746173 A 15-03-2006 EP 1643547 A1 05-04-2006 J P 5052774 B2 17-10-2012 J P 2006104189 A 20-04-2006 KR 20060050962 A 19-05-2006 T W 200619222 A 16-06-2006 US 2006047132 A1 02-03-2006

J P 2006342101 A 21-12-2006 J P 4784729 B2 05-10-2011 J P 2006342101 A 21-12-2006