EP3356318A1

EP3356318A1 - Method of producing 2,4,6-tri-substituted resorcinol

Info

Publication number: EP3356318A1
Application number: EP17786998.9A
Authority: EP
Inventors: Kenchaiah LOHITH; Gurunath POZHAL VENGU; Ramesha GANGANAHALLI; Kiran Puthamane; Gaurav Mediratta
Original assignee: SABIC Global Technologies BV
Current assignee: SABIC Global Technologies BV
Priority date: 2016-09-28
Filing date: 2017-09-19
Publication date: 2018-08-08
Also published as: WO2018060811A1

Abstract

2,4,6-Trialkylresorcinol is produced by the reaction of resorcinol and a C_1-12 alkanol. The reaction is conducted in the presence of a catalyst based on magnesium oxide. The reaction is conducted at a temperature of 300 to 500 °C, a pressure of 100 to 1000 kilopascals, and a molar ratio of C_1-12 alkanol to resorcinol of 5:1 to 20:1. The reaction achieves high conversion of resorcinol and selectivity for 2,4,6-trialkylresorcinol.

Description

METHOD OF PRODUCING 2,4,6-TRI-SUBSTITUTED RESORCINOL

BACKGROUND OF THE INVENTION

[0001] Alkylation of phenol to form, for example, 2,6-dimethylphenol has been the subject of decades of research. See, e.g., U.S. Patent No. 3,446,856 to Hamilton, issued 27 May 1969; U.S. Patent No. 4,954,475 to Bennett et al., issued 4 September 1990; and U.S. Patent No. 7,081,432 to Ingelbrecht et al., issued 25 July 2006. Considerably less research has been conducted on the alkylation of resorcinol (1,3-dihydroxybenzene), and specifically the trialkylation of resorcinol.

[0002] U.S. Patent No. 7,087,705 to Ashtekar et al., issued 8 August 2006, describes a process for the monoalkylation of dihydroxy aromatic compounds, including resorcinol.

Ashtekar' s working examples used hydroquinone as the dihydroxy aromatic compound and methanol as the alkylating agent, and they produced primarily 2-methylhydroquinone, with 2,6-dimethylhydroquinone as a lesser product. No trimethylated product was reported.

[0003] Japanese Patent Application No. JPS 58[1983]-72530 A of Katsuo et al., published 30 April 1983, teaches a method of preparing alkyl-substituted dihydric phenols. The main component of Katsuo' s catalyst is iron oxide, manganese oxide, or chromium oxide. In Working Example 2, Katsuo uses a catalyst containing iron oxide and germanium oxide to prepare 2,4,6-trimethylresorcinol with high selectivity. However, other references suggest that iron oxide-based catalysts decompose a significant fraction of the methanol alkylating agent. See, e.g., U.S. Patent No. 6,593,501 B2 to Ota et al., issued 15 July 2003, column 1, lines 24-38.

[0004] There remains a need for a method of producing 2,4,6-tri-subtituted resorcinol, specifically 2,4,6-trimethylresorcinol, that efficiently utilizes the alkylating agent (e.g., the methanol alkylating agent).

BRIEF SUMMARY OF EMBODIMENTS OF THE INVENTION

[0005] One embodiment is a method of 2,4,6-trialkylresorcinol, the method comprising: reacting resorcinol and a Ci-12 alkanol in the presence of a catalyst comprising magnesium oxide to form 2,4, 6-tri(C 1-12 alkyl)resorcinol; wherein said reacting is conducted at a temperature of 300 to 500 °C, a pressure of 100 to 1000 kilopascals, and a molar ratio of Ci-12 alkanol to resorcinol of 5: 1 to 20: 1; wherein the catalyst comprises 40 to 90 weight percent of the magnesium oxide based on the weight of the catalyst; and wherein the 2,4, 6-tri(C 1-12

alkyl)resorcinol is formed with a selectivity of at least 30 mole percent, based on converted moles of resorcinol. [0006] Another embodiment is a method of producing 2,4,6-trimethylresorcinol, the method comprising: reacting resorcinol and methanol in the presence of a catalyst comprising magnesium oxide to form 2,4,6-trimethylresorcinol; wherein said reacting is conducted at a temperature of 300 to 500 °C, a pressure of 100 to 1000 kilopascals, and a molar ratio of methanol to resorcinol of 5: 1 to 20: 1; wherein the catalyst comprises 40 to 90 weight percent of the magnesium oxide based on the weight of the catalyst; and wherein the

2,4,6-trimethylresorcinol is formed with a selectivity of at least 30 mole percent, based on converted moles of resorcinol.

[0007] These and other embodiments are described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a gas chromatogram of unpurified reaction mixture after eluting from the reactor and passing through a condenser to form a mixture of liquid products and

non-condensable gases; "DMR" is dimethylresorcinol (unspecified isomer(s)); "TMR" is 2,4,6-trimethylresorcinol.

[0009] Figure 2 is a chromatogram from a gas chromatography - mass spectrometry (GC-MS) analysis of the product of the third purification method in Example 1, below.

[0010] Figure 3 is a mass chromatogram for the peak at 13.44 minutes in Figure 2. The peak at 152.09 m/z is consistent with 2,4,6-trimethylresorcinol.

[0011] Figure 4 is a proton nuclear magnetic resonance (^lH NMR) spectrum of

2,4,6-trimethylresorcinol prepared according to Example 1, using the second purification method.

DETAILED DESCRIPTION OF THE INVENTION

[0012] The present inventors have determined that 2,4,6-trialkylresorcinol can be efficiently produced from resorcinol and a Ci-12 alkanol in a process that uses a robust catalyst and efficiently utilizes the Ci-12 alkanol. In a particularly advantageous aspect, the present inventors have determined that 2,4,6-trimethylresorcinol can be efficiently produced from resorcinol and methanol from the catalyst, and efficiently utilizes the methanol alkylating agent.

[0013] Accordingly, one embodiment is a method of producing 2,4,6-trialkylresorcinol, the method comprising reacting resorcinol and a Ci-12 alkanol in the presence of a catalyst comprising magnesium oxide to form 2,4,6-tri(Ci-i2 alkyl)resorcinol; wherein said reacting is conducted at a temperature of 300 to 500 °C, a pressure of 100 to 1000 kilopascals, and a molar ratio of Ci-12 alkanol to resorcinol of 5: 1 to 20: 1; wherein the catalyst comprises 40 to 90 weight percent of the magnesium oxide based on the weight of the catalyst; and wherein the 2,4,6-tri(Ci- 12 alkyl)resorcinol is formed with a selectivity of at least 30 mole percent, based on converted moles of resorcinol.

[0014] The Ci-12 alkanol can be, for example, methanol, ethanol, propanol, hexanol, 2- ethylhexanol, or a combination thereof. In a preferred embodiment, the Ci-12 alkanol comprises methanol, ethanol, propanol, or a combination thereof. More preferably, the Ci-12 alkanol is methanol.

[0015] Another embodiment is a method of producing 2,4,6-trimethylresorcinol, the method comprising: reacting resorcinol and methanol in the presence of a catalyst comprising magnesium oxide to form 2,4,6-trimethylresorcinol; wherein said reacting is conducted at a temperature of 300 to 500 °C, a pressure of 100 to 1000 kilopascals, and a molar ratio of methanol to resorcinol of 5: 1 to 20: 1; wherein the catalyst comprises 40 to 90 weight percent of the magnesium oxide based on the weight of the catalyst; and wherein the

[0016] The above-described methods utilize a catalyst comprising magnesium oxide at 40 to 90 weight percent, or 50 to 90 weight percent, based on the weight of the catalyst. In a very specific embodiment, the catalyst is the product of calcining a catalyst precursor

comprising, based on the weight of the catalyst precursor, 70 to 98 weight percent magnesium oxide, 0.1 to 2 weight percent copper oxide or a copper oxide precursor, 0.5 to 8 weight percent of a binder comprising a hydrous magnesium aluminosilicate, 1 to 15 weight percent of a pore- former, 0.2 to 5 weight percent of a lubricant, and 0.2 to 15 weight percent water.

[0017] The catalyst precursor comprises magnesium oxide (MgO). In some

embodiments, the magnesium oxide has a Brunauer-Emmett- Teller (BET) surface area of at least 70 meter²/gram. Within this limit, the magnesium oxide surface area can be 70 to 500 meter²/gram, or 100 to 500 meter²/gram, or 150 to 500 meter²/gram. BET surface areas were determined on a Micromeritics ASAP 2010 instrument. The samples were thoroughly degassed at 300 °C for 5 hours under vacuum to remove water and other physically adsorbed species. The measurements were made using nitrogen gas as the adsorbent at 77 K and a multipoint method of calculation was used for determining surface area of the catalyst. Pore volume, expressed in units of centimeter³/gram, was determined at relative pressure P/Po = 0.99, and average pore diameter, expressed in units of Angstroms, was calculated using the formula 10^"4(V)/(BET SA), where "V" is the pore volume in units of centimeter³/gram, and "BET SA" is the BET surface area in units of meter²/gram. [0018] In some embodiments, the magnesium oxide has an aspect ratio of less than or equal to 3: 1, or 1.1: 1 to 3: 1, or 1.2: 1 to 2.5: 1, or 1.3: 1 to 2: 1. Aspect ratio is defined as the number average ratio of the largest particle dimension to the smallest orthogonal dimension of the same particle. Aspect ratio can be determined by laser diffraction.

[0019] In some embodiments, the catalyst precursor comprises the magnesium oxide in an amount of 70 to 98 weight percent, based on the total weight of the catalyst precursor. Within this range, the magnesium oxide amount can be 75 to 95 weight percent, or 78 to 90 weight percent.

[0020] In some embodiments, the catalyst precursor comprises copper oxide or a copper oxide precursor. As used herein, copper oxide refers to cupric oxide (CuO). In some embodiments, the copper oxide or a copper oxide precursor comprises cupric oxide, cupric nitrate, cuprous carbonate, a hydrate of one of the foregoing, or a combination thereof.

[0021] In some embodiments, the catalyst precursor comprises the copper oxide or copper oxide precursor in an amount of 0.1 to 2 weight percent, based on the total weight of the catalyst precursor. Within this range, the copper oxide or copper oxide precursor amount can be 0.2 to 1 weight percent, or 0.3 to 0.8 weight percent.

[0022] In some embodiments, the catalyst precursor further comprises a binder comprising a hydrous magnesium aluminosilicate. Hydrous magnesium aluminosilicates are naturally occurring materials, and they are commercially available at various levels of purification. Examples of purified hydrous magnesium aluminosilicates include MIN-U-GEL™ 200, MIN-U-GEL™ 400, MIN-U-GEL™ 500, MIN-U-GEL™ PC, and MIN-U-GEL™ FG, all available from ActiveMinerals International LLC. An example of a highly purified hydrous magnesium aluminosilicate is ACTI-GEL™ 208, available from ActiveMinerals International LLC. In some embodiments, the hydrous magnesium aluminosilicate comprises a hydrated or hydroxylated magnesium aluminosilicate. When present in the catalyst precursor, the hydrous magnesium aluminosilicate can be used in an amount of 0.5 to 8 weight percent, based on the total weight of the catalyst precursor. Within this range, the hydrous magnesium aluminosilicate amount can be 1 to 6 weight percent, or 1.5 to 5.5 weight percent.

[0023] In some embodiments, the catalyst precursor comprises a pore-former. As used herein, the term pore-former refers a substance capable of aiding the formation of pores in the calcined catalyst (i.e., the product of calcining the catalyst precursor). Pore-formers include paraffin wax, polyethylene wax, microcrystalline wax, montan wax, cellulose, carboxymethyl cellulose, cellulose acetate, starch, walnut powder, citric acid, polyethylene glycol, oxalic acid, stearic acid, C10-C28 anionic surfactants (including those with neutralized carboxylic acid, phosphoric acid, and sulfonic acid groups), C10-C28 cationic surfactants (including those with ammonium and phosphonium groups), and combinations thereof. In some embodiments, the pore-former comprises a polyethylene glycol. When present in the catalyst precursor, the pore-former can be used in an amount of 1 to 15 weight percent, based on the total weight of the catalyst precursor. Within this range, the pore-former amount can be 2 to 10 weight percent.

[0024] In some embodiments, the catalyst precursor comprises a lubricant. Suitable lubricants include graphite, C8-C24 carboxylic acids (including octanoic acid (caprylic acid), decanoic acid, dodecanoic acid (lauric acid), tetradecanoic acid (myristic acid), hexadecanoic acid (palmitic acid), octadecanoic acid (stearic acid), eicosanoic acid (arachidic acid), docosanoic acid (behenic acid), and tetracosanoic acid), magnesium salts of C8-C24 carboxylic acids, talcs, silicas, waxes, glycerol, starches, and combinations thereof. In some embodiments, the lubricant comprises magnesium stearate. When present in the catalyst precursor, the lubricant can be used in an amount of 0.2 to 5 weight percent, based on the total weight of the catalyst precursor. Within this range, the lubricant amount can be 0.4 to 3.5 weight percent, or 0.6 to 2.5 weight percent.

[0025] In some embodiments, the catalyst precursor comprises water. In some embodiments, the water is deionized. When present in the catalyst precursor, the water can be used in an amount of 0.2 to 15 weight percent, based on the total weight of the catalyst precursor. Within this range, the water amount can be 0.6 to 12 weight percent.

[0026] Procedures for forming the catalyst precursor composition, and for shaping it into pellets, are provided in the working examples below. In some embodiments, the catalyst precursor has a density of 1.2 to 2 grams per milliliter, or 1.3 to 1.8 grams per milliliter, at 23 °C. In this context, density refers to the unpacked density of catalyst precursor pellets, determined as described in the working examples.

[0027] In a very specific embodiment of the catalyst precursor, it comprises 75 to 95 weight percent of the magnesium oxide; 0.2 to 1 weight percent of the copper oxide or copper oxide precursor; 1 to 6 weight percent of the binder comprising a hydrous magnesium

aluminosilicate; 2 to 10 weight percent of the pore-former; 0.4 to 3.5 weight percent of the lubricant; and 0.6 to 12 weight percent of the water.

[0028] The catalyst can be prepared from the catalyst precursor by a method comprising: exposing the catalyst precursor in any of its above-described variations to a nitrogen gas flow having a weight hourly space velocity of 0.05 to 0.8 hour^"1, or 0.1 to 0.4 hour^"1, wherein the nitrogen gas flow has a temperature of 350 to 550 °C, or 400 to 500 °C, and is conducted for a time of 5 to 30 hours, or 8 to 24 hours, and wherein the temperature of the nitrogen gas flow is increased to the temperature of 350 to 550 °C at a rate of 0.5 to 5 °C/minute, or 1 to 4 °C/minute. This method of forming a resorcinol alkylation catalyst can also be called a method of calcining the catalyst precursor.

[0029] In some embodiments, the freshly calcined resorcinol alkylation catalyst exhibits a crush strength of 1 to 20 Newtons/millimeter, or 5 to 20 Newtons/millimeter, determined according to ASTM D4179-11, "Standard Test Method for Single Pellet Crush Strength of Formed Catalysts and Catalyst Carriers".

[0030] The reaction of resorcinol and the Ci-12 alkanol (e.g., methanol) is conducted at a temperature of 300 to 500 °C. Within this range, the temperature can be 330 to 480 °C, or 350 to 450 °C.

[0031] The reaction of resorcinol and the Ci-12 alkanol (e.g., methanol) is conducted at a pressure (absolute) of 100 to 1000 kilopascals. Within this range, the pressure can be 150 to 500 kilopascals.

[0032] The reaction of resorcinol and the Ci-12 alkanol (e.g., methanol) is conducted at a molar ratio of the Ci-12 alkanol to resorcinol of 5: 1 to 20: 1. Within this range, the molar ratio can be 6: 1 to 15: 1. For example, when the Ci-12 alkyl alcohol is methanol, the reaction of resorcinol and methanol is conducted at a molar ratio of methanol to resorcinol of 5: 1 to 20: 1. Within this range, the molar ratio can be 6: 1 to 15: 1.

[0033] In some embodiments, the reaction is conducted at a weight hourly space velocity of 0.1 to 2 hour^"1. As used herein, the weight hourly space velocity is the combined hourly mass flow of the Ci-12 alkanol (e.g., methanol) and resorcinol divided by the catalyst mass.

[0034] The desired 2,4,6-trialkylresorcinol (e.g., 2,4,6-trimethylresorcinol) is formed with a selectivity of at least 30 mole percent, based on converted moles of resorcinol. Within this limit, the selectivity can be 30 to 80 mole percent, or 50 to 70 mole percent.

[0035] In addition to the Ci-12 alkanol and resorcinol, the reactor feed can comprise water. In some embodiments, the reaction is conducted in the presence of 5 to 25 weight percent water, or 10 to 25 weight percent water, based on the total weight of Ci-12 alkanol, resorcinol, and water.

[0036] In some embodiments, reacting the Ci-12 alkanol and resorcinol comprises converting at least 50 percent of the resorcinol. Within this limit, the resorcinol conversion can be 50 to 100 percent, or 60 to 100 percent. In Example 2, a conversion of greater than 99 percent is demonstrated.

[0037] In a very specific embodiment of the method, reacting resorcinol and methanol is conducted at a temperature of 330 to 480 °C, a pressure of 150 to 500 kilopascals, and a molar ratio of methanol to resorcinol of 6: 1 to 15: 1; the catalyst is the product of calcining a catalyst precursor comprising, based on the weight of the catalyst precursor, 70 to 98 weight percent magnesium oxide, 0.1 to 2 weight percent copper oxide or a copper oxide precursor, 0.5 to 8 weight percent of a binder comprising a hydrous magnesium aluminosilicate, 1 to 15 weight percent of a pore-former, 0.2 to 5 weight percent of a lubricant, and 0.2 to 15 weight percent water; reacting is conducted in the presence of 5 to 25 weight percent water, based on the total weight of methanol, resorcinol, and water; and reacting comprises converting at least 50 percent of the resorcinol.

[0038] The invention includes at least the following embodiments.

[0039] Embodiment 1: A method of producing 2,4,6-trialkylresorcinol, the method comprising: reacting resorcinol and a Ci-12 alkanol in the presence of a catalyst comprising magnesium oxide to form 2,4, 6-tri(C 1-12 alkyl)resorcinol; wherein said reacting is conducted at a temperature of 300 to 500 °C, a pressure of 100 to 1000 kilopascals, and a molar ratio of Ci-12 alkanol to resorcinol of 5: 1 to 20: 1; wherein the catalyst comprises 40 to 90 weight percent of the magnesium oxide based on the weight of the catalyst; and wherein the 2,4,6-tri(Ci-i2 alkyl)resorcinol is formed with a selectivity of at least 30 mole percent, based on converted moles of resorcinol.

[0040] Embodiment 2: The method of embodiment 1, wherein the Ci-12 alkanol comprises methanol, ethanol, propanol, hexanol, 2-ethylhexanol, or a combination thereof.

[0041] Embodiment 3: The method of embodiments 1 or 2, wherein the catalyst is the product of calcining a catalyst precursor comprising, based on the weight of the catalyst precursor, 70 to 98 weight percent magnesium oxide; 0.1 to 2 weight percent copper oxide or a copper oxide precursor; 0.5 to 8 weight percent of a binder comprising a hydrous magnesium aluminosilicate; 1 to 15 weight percent of a pore-former; 0.2 to 5 weight percent of a lubricant; and 0.2 to 15 weight percent water.

[0042] Embodiment 4: The method of any one of embodiments 1 to 3, wherein said reacting is conducted in the presence of 5 to 25 weight percent water, based on the total weight of Ci-12 alkanol, resorcinol, and water.

[0043] Embodiment 5: The method of any one of embodiments 1 to 4, wherein said reacting comprises converting at least 50 percent of the resorcinol.

[0044] Embodiment 6: The method of any one of embodiments 1 to 5, wherein the catalyst has a surface area of 50 to 200 meter²/gram. [0045] Embodiment 7: The method of any one of embodiments 1 to 6, wherein said reacting is conducted at a weight hourly space velocity of 0.1 to 2 hour^"1.

[0046] Embodiment 8: A method of producing 2,4,6-trimethylresorcinol, the method comprising: reacting resorcinol and methanol in the presence of a catalyst comprising magnesium oxide to form 2,4,6-trimethylresorcinol; wherein said reacting is conducted at a temperature of 300 to 500 °C, a pressure of 100 to 1000 kilopascals, and a molar ratio of methanol to resorcinol of 5: 1 to 20: 1; wherein the catalyst comprises 40 to 90 weight percent of the magnesium oxide based on the weight of the catalyst; and wherein the 2,4,6- trimethylresorcinol is formed with a selectivity of at least 30 mole percent, based on converted moles of resorcinol.

[0047] Embodiment 9: The method of embodiment 8, wherein the catalyst is the product of calcining a catalyst precursor comprising, based on the weight of the catalyst precursor, 70 to 98 weight percent magnesium oxide, 0.1 to 2 weight percent copper oxide or a copper oxide precursor, 0.5 to 8 weight percent of a binder comprising a hydrous magnesium aluminosilicate, 1 to 15 weight percent of a pore-former, 0.2 to 5 weight percent of a lubricant, and 0.2 to 15 weight percent water.

[0048] Embodiment 10: The method of embodiment 8 or 9, wherein said reacting is conducted in the presence of 5 to 25 weight percent water, based on the total weight of methanol, resorcinol, and water.

[0049] Embodiment 11: The method of any one of embodiments 8-10, wherein said reacting comprises converting at least 50 percent of the resorcinol.

[0050] Embodiment 12: The method of any one of embodiments 8-11, wherein the catalyst has a surface area of 50 to 200 meter²/gram.

[0051] Embodiment 13: The method of any one of embodiments 8-12, wherein said reacting is conducted at a weight hourly space velocity of 0.1 to 2 hour^"1.

[0052] Embodiment 14: The method of embodiment 8, wherein said reacting is conducted at a temperature of 330 to 480 °C, a pressure of 150 to 500 kilopascals, and a molar ratio of methanol to resorcinol of 6: 1 to 15: 1; the catalyst is the product of calcining a catalyst precursor comprising, based on the weight of the catalyst precursor, 70 to 98 weight percent magnesium oxide, 0.1 to 2 weight percent copper oxide or a copper oxide precursor, 0.5 to 8 weight percent of a binder comprising a hydrous magnesium aluminosilicate, 1 to 15 weight percent of a pore-former, 0.2 to 5 weight percent of a lubricant, and 0.2 to 15 weight percent water; said reacting is conducted in the presence of 5 to 25 weight percent water, based on the total weight of methanol, resorcinol, and water; and said reacting comprises converting at least 50 percent of the resorcinol.

[0053] All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. Each range disclosed herein constitutes a disclosure of any point or sub-range lying within the disclosed range.

[0054] The invention is further illustrated by the following non-limiting examples. EXAMPLE 1

[0055] The following components were used in the working examples.

Table 1

[0056] A catalyst precursor was prepared using the formulation summarized in Table 2, where component amounts are expressed in parts by weight. To 85.5 grams of magnesium oxide, 4.3 grams of PEG, 4.3 grams of HPMAS, 0.9 grams of Cu(N0₃)₂.3H₂0 and 0.9 gram of graphite were added and thoroughly mixed. To the resulting powder mix, 4.3 grams of water was added dropwise and dispersed by mixing. The powder mixture was pressed into 4.76 millimeters (3/16 inch) diameter pellets using a die press. The pellets were used as the catalyst precursor.

Table 2

[0057] The vapor phase methylation reaction between resorcinol and methanol was conducted in a continuous packed bed reactor. The reactor is a stainless steel tube having a 12.7 millimeter (0.5 inch) inner diameter. The reactor is heated using an electric furnace.

[0058] Five (5) grams of the catalyst precursor was packed at the center of the reactor tube. Further, the catalyst bed was supported with glass beads. The catalyst precursor was calcined at 390 °C for 22 hours under nitrogen at a weight hourly space velocity (WHSV) of 0.11 hour^"1 with no back-pressure in the system. After 22 hours of calcination, the reactor temperature was raised at a rate of 0.5 °C/minute to 460 °C. Before the reactant feed was pumped to the reactor, the reactor pressure was increased to 270 kilopascals absolute pressure (1.7 bar gauge), and that pressure was maintained throughout the reaction time. The feed to the reactor was a homogenous solution of resorcinol and methanol (1:8 molar ratio) and water (20% of total weight). The liquid feed was pumped into the reactor using a high performance liquid chromatography (HPLC) pump at a flow rate of 0.2 millimeters/minute. As the reactor temperature was very high (350-450°C), the liquid feed that enters into the reactor vaporizes before it encounters the catalyst. The alkylation reactions occurred in the catalyst bed, and all the gaseous material exiting the reactor passed through a condenser to form a mixture of liquid products and non-condensable gases. Figure 1 is a gas chromatogram of the unpurified reaction mixture. In Figure 1, "DMR" is dimethylresorcinol (unspecified isomer(s)); and "TMR" is 2,4,6-trimethylresorcinol. This mixture of liquid products and non-condensable gases was separated in a gas-liquid separator. The liquid products were purified using extraction, distillation, and crystallization. Analysis of the unpurified reaction mixture indicated 65% conversion of resorcinol with a 62% selectivity for TMR.

[0059] In a first purification method, one weight part of the liquid products was washed with 2 weight parts water. This procedure was repeated two more times and removed most of the unreacted resorcinol and methanol. The product was concentrated further to produce a viscous liquid to which ten volume parts hexane were added to produce a precipitate, and the resulting liquid/solid mixture was stirred for 30 minutes at 50 °C. The powder was filtered and washed 2 times with hexane to yield a crude product with 2,4,6-trimethylresorcinol of 85 weight percent purity, the primary contaminants being dimethyl resorcinols and monomethyl resorcinols. The product was further purified by crystallization as follows.

[0060] Ten (10) grams of the crude product having 85% purity was dissolved in a minimum amount of acetone (5 to 10 milliliters), and water was added slowly until turbidity was observed. The resulting mixture was stirred, then heated to dissolve the turbid particles. The mixture was filtered, and the filtrate was aside for two to three hours, during which time crystals formed. The crystals were filtered, washed with 20 milliliters of water, and dried at room temperature. The final product was characterized by GC, GC-MS and ^lH NMR, and had a purity of 98.3%.

[0061] In a second purification method, one weight part of the liquid products was washed with 2 weight parts water. This procedure was repeated two more times and removed most of the unreacted resorcinol and methanol. About 200 grams of the washed product was added to a 500 milliliter round bottom flask, which was connected to distillation column and condenser. The condenser was further connected to vacuum pump equipped with a pressure gauge. Above the condenser a digital thermometer was used to monitor the vapor temperature. The round bottom flask, the contents of which were at atmospheric pressure, was immersed in an oil bath, which was heated to an initial temperature of 150 °C. Under these conditions, most of the methanol was distilled off. The temperature was then increased to 180 °C and vacuum was applied to create an absolute pressure of 50 kilopascals (500 millibars). Under these conditions, which were maintained for one hour, water and the remaining methanol were distilled off. The temperature was slowly increased to 200 °C, and the vacuum increased to yield an absolute pressure of 5 kilopascals (50 millibars). Five fractions each of 20 to 30 grams were collected and analyzed by GC. Fractions 1 to 3 were rich in resorcinol and other impurities. Fractions 4 and 5 had more than 80% of TMR along with monomethyl resorcinols and dimethyl resorcinols. Finally, the temperature was increased to 220 °C and vacuum increased to yield an absolute pressure less than 0.5 kilopascal (5 millibars). A single fraction of about 5 grams was collected, but was not rich in TMR. The purity of the isolated fractions was investigated using gas chromatography.

[0062] Gas chromatography utilizing a Shimadzu GC-17A gas chromatograph with flame ionization detector was used for quantitative analysis of reaction samples. 50 microliters of sample were diluted with 950 microliters of acetonitrile for analysis. The GC inlet temperature was maintained at 280 °C with a split ratio of 20 and flow rate of 1 milliliter/minute. The GC was equipped with an HP-1 column of dimensions 30 meters (length) by 0.250 millimeter (inner diameter) by 0.25 micrometer (film thickness). The temperature of the flame ionization detector was at 300 °C with H₂ and air flow at 40 milliliters/minute and 400 milliliters/minute, respectively. The oven temperature was initially at 60 °C (hold for 0 mins), ramped to 130 °C (ramp rate of 10 °C/minute, hold for 3 minutes) and ramped to 300 °C (ramp rate of 10 °C/minute, hold for 1 minute). [0063] Samples were further analyzed by gas chromatography-mass spectrometry. A Thermo Scientific Trace GC Ultra with quadrupole detector was used for peak identification. Fifty (50) microliters of sample were diluted with 950 microliters of acetonitrile for analysis. The GC inlet temperature was maintained at 280 °C with a split ratio of 9 and a flow rate of 1.1 milliliter s/minute. The GC was equipped with an HP-5 column of dimensions 30 meters (length) by 0.320 millimeters (inner diameter) by 0.25 micrometer (film thickness). The MS ion source temperature was maintained at 200 °C with solvent cut-off time of 4 minutes. The oven temperature was initially at 60 °C (hold for 2 minutes), and ramped to 300 °C (ramp rate of 10 °C/minute, hold for 10 minutes). The auxiliary temperature was maintained at 280 °C.

[0064] Fractional crystallization was used to further purify the product, using the procedure described for the first purification method.

[0065] In a third purification method, 10 grams of crude liquid products were washed with 50 milliliters of 1% aqueous sodium hydroxide, and the aqueous layer was decanted. To the organic layer was added 50 milliliters of dichloromethane and 100 milliliters of water, and the resulting mixture was shaken thoroughly in a separatory funnel. The mixture was allowed to phase separate, and the dichloromethane layer was removed and dried under vacuum to yield a powder. The obtained product was analyzed using gas GC and GC-MS.

[0066] The crude TMR with 85% purity was analyzed by GC-MS. Figure 2 shows the gas chromatogram, and Figure 3 the mass fragmentation pattern for the peak at 13.44 minutes, which corresponds to TMR peak. The MS peak at m/z of 152.09 for the peak at 13.44 in Figure 2 is consistent with the TMR mass, and the peak at m/z of 137.05 is consistent with loss of one methyl group.

[0067] The trimethylation in TMR was confirmed by performing ^lH NMR spectroscopy in CDCI3. Figure 4 shows the ^lH NMR spectrum for TMR. The peak at 2.18 ppm for 9 protons indicates the presence of three methyl groups. And two protons from the free hydroxyl group at 4.52 ppm supports that methylation occurred on the aromatic ring and not as O-methylation. The peak at 6.75 ppm for one proton is consistent with a single hydrogen atom directly bonded to the aromatic ring.

EXAMPLE 2

[0068] In this example, the resorcinol alkylation conditions were the same as those in Example 1, except that the weight hourly space velocity (WHSV) was 1 hour^"1 rather than 0.11 hour^"1 in Example 1. The reaction achieved >99% resorcinol conversion and a TMR selectivity of 61%.

Claims

1. A method of producing 2,4,6-trialkylresorcinol, the method comprising:

reacting resorcinol and a Ci-12 alkanol in the presence of a catalyst comprising magnesium oxide to form 2,4, 6-tri(C 1-12 alkyl)resorcinol;

wherein said reacting is conducted at a temperature of 300 to 500 °C, a pressure of 100 to 1000 kilopascals, and a molar ratio of Ci-12 alkanol to resorcinol of 5:1 to 20:1;

wherein the catalyst comprises 40 to 90 weight percent of the magnesium oxide based on the weight of the catalyst; and

wherein the 2,4,6-tri(Ci-i2 alkyl)resorcinol is formed with a selectivity of at least 30 mole percent, based on converted moles of resorcinol.

2. The method of claim 1, wherein the Ci-12 alkanol comprises methanol, ethanol, propanol, hexanol, 2-ethylhexanol, or a combination thereof.

3. The method of claim 1 or 2, wherein the catalyst is the product of calcining a catalyst precursor comprising, based on the weight of the catalyst precursor,

70 to 98 weight percent magnesium oxide;

0.1 to 2 weight percent copper oxide or a copper oxide precursor;

0.5 to 8 weight percent of a binder comprising a hydrous magnesium aluminosilicate;

1 to 15 weight percent of a pore-former;

0.2 to 5 weight percent of a lubricant; and

0.2 to 15 weight percent water.

4. The method of any one of claims 1 to 3, wherein said reacting is conducted in the presence of 5 to 25 weight percent water, based on the total weight of Ci-12 alkanol, resorcinol, and water.

5. The method of any one of claims 1 to 4, wherein said reacting comprises converting at least 50 percent of the resorcinol.

6. The method of any one of claims 1 to 5, wherein the catalyst has a surface area of 50 to 200 meter²/gram.

7. The method of any one of claims 1 to 6, wherein said reacting is conducted at a weight hourly space velocity of 0.1 to 2 hour^"1.

8. A method of producing 2,4,6-trimethylresorcinol, the method comprising:

reacting resorcinol and methanol in the presence of a catalyst comprising magnesium oxide to form 2,4,6-trimethylresorcinol;

wherein said reacting is conducted at a temperature of 300 to 500 °C, a pressure of 100 to 1000 kilopascals, and a molar ratio of methanol to resorcinol of 5: 1 to 20: 1 ;

wherein the 2,4,6-trimethylresorcinol is formed with a selectivity of at least 30 mole percent, based on converted moles of resorcinol.

9. The method of claim 8, wherein the catalyst is the product of calcining a catalyst precursor comprising, based on the weight of the catalyst precursor,

70 to 98 weight percent magnesium oxide;

0.1 to 2 weight percent copper oxide or a copper oxide precursor;

1 to 15 weight percent of a pore-former;

0.2 to 5 weight percent of a lubricant; and

0.2 to 15 weight percent water.

10. The method of claim 8 or 9, wherein said reacting is conducted in the presence of 5 to 25 weight percent water, based on the total weight of methanol, resorcinol, and water.

11. The method of any one of claims 8-10, wherein said reacting comprises converting at least 50 percent of the resorcinol.

12. The method of any one of claims 8-11, wherein the catalyst has a surface area of 50 to 200 meter²/gram.

13. The method of any one of claims 8-12, wherein said reacting is conducted at a weight hourly space velocity of 0.1 to 2 hour^"1.

14. The method of claim 8, wherein said reacting is conducted at a temperature of 330 to 480 °C, a pressure of 150 to 500 kilopascals, and a molar ratio of methanol to resorcinol of 6: 1 to 15: 1;

the catalyst is the product of calcining a catalyst precursor comprising, based on the weight of the catalyst precursor,

70 to 98 weight percent magnesium oxide,

0.1 to 2 weight percent copper oxide or a copper oxide precursor,

0.5 to 8 weight percent of a binder comprising a hydrous magnesium aluminosilicate,

1 to 15 weight percent of a pore-former,

0.2 to 5 weight percent of a lubricant, and

0.2 to 15 weight percent water;

said reacting is conducted in the presence of 5 to 25 weight percent water, based on the total weight of methanol, resorcinol, and water; and

said reacting comprises converting at least 50 percent of the resorcinol.