WO2021257717A1

WO2021257717A1 - Method for making bio-based acrylic acid

Info

Publication number: WO2021257717A1
Application number: PCT/US2021/037650
Authority: WO
Inventors: Dieter SCHEIBEL; Robb Bagge; Lyudmyla CHUMAKOVA; Tao Gu
Original assignee: Nitto Denko Corporation
Priority date: 2020-06-19
Filing date: 2021-06-16
Publication date: 2021-12-23
Also published as: TW202208317A

Abstract

Described herein are methods for the preparation of bio-based acrylic acid from bio-based methyl lactate. Some methods involve the use of an azeotropic distillate of methyl acrylate and methanol. The methods enhance bio-based acrylic acid production yield.

Description

METHOD FOR MAKING BIO-BASED ACRYLIC ACID

Inventors: Dieter Scheibel, Robb Bagge, Lyudmyla Chumakova, Tao Gu

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of United States Provisional Application No. 63/041 ,382, filed June 19, 2020, which is incorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

The current disclosure describes a method for making pure bio-based acrylic acid and butyl acrylate.

BACKGROUND OF THE DISCLOSURE

Acrylic acid and acrylate esters have a variety of industrial uses, typically consumed in the form of polymers. In turn, these polymers are commonly used in the manufacture of adhesives, binders, coatings, paints, polishes, detergents, flocculants, dispersants, thixotropic agents, sequestrants, superabsorbent polymers and the like. Superabsorbent polymers are used in disposable absorbent articles including diapers and hygienic products. Acrylic acid is commonly made from petroleum sources. For example, acrylic acid has long been prepared by catalytic oxidation of propylene and other known methods. Petroleum-based acrylic acid contributes to greenhouse emissions due to its high petroleum derived carbon content. Furthermore, petroleum is a non-renewable material, as it takes hundreds of thousands of years to form naturally and only a short time to consume. As petrochemical resources become increasingly scarce, more expensive, and subject to regulations for carbon dioxide (CO2) emissions, there exists a growing need for alternative, bio-based acrylic acid and acrylate esters. Many attempts have been made over the last 40 to 50 years to make bio-based acrylic acid and acrylate esters from non-petroleum sources, such as lactic acid (also known as 2-hydroxypropionic acid), 3-hydroxypropionic acid, glycerin, carbon monoxide and ethylene oxide, carbon dioxide and ethylene, and crotonic acid, but none is without drawbacks.

Accordingly, there exists a need for a high yield bio-based acrylic acid and/or acrylate ester manufacturing process. SUMMARY OF THE DISCLOSURE

The current disclosure includes methods for making butyl acrylate and acrylic acid from renewable resources. The current disclosure also describes methods for making butyl acrylate and acrylic acid in high yield with a high percentage of bio-based material origins.

Some embodiments include a method for making bio-based acrylic acid. Some embodiments include a method for making bio-based butyl acrylate. Some embodiments include using a bio-based methyl lactate starting material, converting the bio-based methyl lactate material into a bio-based methyl 2-acetoxypropionate, and pyrolyzing the bio-based methyl 2-acetoxypropionate to afford a bio-based methyl acrylate solution. In some examples, the pyrolysis of methyl 2-acetoxypropionate comprises passing the distilled bio-based methyl 2-acetoxypropionate over silicon carbide at a high temperature to afford the bio-based methyl acrylate. In some embodiments, methyl acrylate may be a reactant in a butyl acrylate synthetic process, which upon distillation may provide an azeotropic mixture of methyl acrylate and methanol as a by-product. In some examples, the azeotropic distillate comprising methanol and methyl acrylate, wherein the azeoptropic distillate comprises greater than 33% v/v methyl acrylate, is saponified with a strong base to generate a basic saponified distillate, which is neutralized with a strong acid to generate an acrylic acid product, and the acrylic acid product is extracted with a polar solvent.

Some embodiments include reacting a mixture comprising methyl lactate and an acetylating agent, such as acetic anhydride, to form methyl 2-acetoxypropionate.

Some embodiments include heating methyl 2-acetoxypropionate to form methyl acrylate.

Some embodiments include reacting a mixture comprising methyl acrylate, n- butanol, and an acid catalyst (such as toluenesulfonic acid), optionally with heating, to form butyl acrylate and methanol.

Some embodiments include reacting a mixture comprising methyl acrylate, methanol, water, and a base to form acrylic acid. In some embodiments, a bio-based acrylate monomer may be made as described herein. In some embodiments, a bio-based butyl acrylate monomer may be made as described herein.

DETAILED DESCRIPTION

The current disclosure includes methods for making bio-based acrylic acid. Also described herein are methods for making bio-based butyl acrylate. Bio-based renewable resources reduce the need for petroleum-based production of acrylates. The current disclosure includes methods for making acrylic acid from renewable lactic acid derivatives. Also described herein are methods for converting methyl lactate to acrylic acid using a methanol/methyl acrylate azeotrope as a source reactant.

As used herein, the term “azeotrope” refers to a constant boiling point mixture of two or more liquids whose proportions cannot be altered or changed by simple distillation.

As used herein, the term “bio-based” refers to a renewable material

As used herein, the term “reactant” refers to a substance that takes part in and undergoes change during a reaction.

As used herein, the term “renewable material" refers to a material that is produced from a renewable resource.

As used herein, the term “renewable resource” refers to a resource that is produced via a natural process at a rate comparable to its rate of consumption (e.g., within a 100 year time frame). The resource may be replenished naturally, or via agricultural techniques. Nonlimiting examples of renewable resources include plants (e.g., sugar cane, beets, corn, potatoes, citrus fruit, woody plants, ligno-cellulose, hemicellulose, cellulosic waste), animals, fish, bacteria, fungi, and forestry products. These renewable resources may be naturally occurring, hybrids, or genetically engineered organisms. Resources such as crude oil, coal, natural gas, and peat, which take longer than 100 years to form, are not considered renewable resources. Processing and use of petroleum-based resources contribute to carbon dioxide emissions. The materials of the present disclosure, being derived from renewable resources, may help reduce global warming potential and fossil fuel consumption.

As used herein, the term “petroleum-based” material refers to a material that is produced from fossil material, such as petroleum, natural gas, coal, etc.

As used herein, the term "bio-based content" refers to the amount of carbon from a renewable resource in a material as a percent of the weight (mass) of the total organic carbon in the material, as determined by ASTM D6866-18, Method B (see section 3.3.9 of ASTM D6866-18). "Bio-based carbon content", "bio-based content", "biogenic carbon content", "bio-based content", "biomass-derived carbon" herein refer to the same thing and are all measured in wt.-%. Herein, the term “bio-based carbon content” is used. ASTM D6866-12, Method B lab results report the percentage of biobased carbon content relative to total carbon, and not to total mass of the sample or molecular weight. ASTM D6866-12, Method B (see section 9 of ASTM D6866-18) requires the percent modern carbon value (pMC) reported to be multiplied by a correction factor of 0.95 to account for excess carbon-14 in the atmosphere due to nuclear weapons testing. Recently, ASTM D6866-12 was superseded by ASTM D6866-21. For the purposes of the present disclosure, the term "bio-based carbon content" as used herein is defined by the equation:

Bio-based carbon content=pMC^*1.00(%)

Use of the term “may” or “may be” should be construed as shorthand for “is” or “is not” or, alternatively, “does” or “does not” or “will” or “will not,” etc. For example, the statement “the methyl lactate may be used without further purification” should be interpreted as, for example, “the methyl lactate is used without further purification,” or “the methyl lactate is not used without further purification.”

Some embodiments include the preparation of bio-based acrylic acid. Some embodiments include the preparation of bio-based butyl acrylate. Some embodiments include the preparation of bio-based methyl acrylate. In some embodiments, the preparation of bio-based methyl acrylate employs bio-based methyl lactate as a renewable resource starting material. In another embodiment, the preparation of biobased butyl acrylate employs bio-based methyl lactate as a renewable resource starting material. In some examples, the preparation of bio-based acrylic acid employs a bio-based methyl lactate reactant as a renewable resource starting material. Some embodiments include the synthesis of bio-based methyl acrylate from methyl lactate via intermediate compound methyl 2-acetoxypropionate. In some embodiments, methyl 2-acetoxypropionate is prepared by the acetylation of methyl lactate. In other examples, reactant methyl 2-acetoxypropionate is converted to methyl lactate via pyrolysis. Some examples include the use of silicon carbide (SiC) in the pyrolysis reaction of methyl 2-acetoxypropionate to afford methyl acrylate.

Some methods of preparing a bio-based acrylic material, such as acrylic acid or butyl acrylate, include reacting a mixture comprising methyl lactate and an acetylating agent, such as acetic anhydride, to form methyl 2-acetoxypropionate.

In some examples, the molar ratio of methyl acrylate to acetylating agent, such as acetic anhydride, may be about 1 :4 to about 4:1 , e.g., a ratio of about 0.8: 1.2 to 1.2:0.8, about 0.9:1.1 to 1.1 :9, or about 1 :1 molar.

For some reactions of a mixture comprising methyl lactate and an acetylating agent, such as acetic anhydride, to form methyl 2-acetoxypropionate, an ion-exchange acidic resin may be present. In some embodiments, the ion-exchange resin may be an acidic resin in a hydrogen form. In some embodiments, the ion-exchange resin may be a strongly acidic cation exchange resin. In some embodiments, the ion- exchange resin may be Amberlyst^®, Amberlite™, and/or Dowex^®. In some cases, the ion-exchange resin may be a sulfonic acid ion exchange resin. In some embodiments, the sulfonic acid ion-exchange resin may be Amberlyst^®. In some embodiments, the Amberlyst^® may be Amberlyst^® 15 (Micropore Sigma Aldrich, St. Louis, MO).

A reactions of a mixture comprising methyl lactate and an acetylating agent, such as acetic anhydride, to form methyl 2-acetoxypropionate, may be done for any suitable amount of time, such as about 1 hour to about 20 hours, e.g., 2 hours to 18 hours, or about 15-20 hours.

The methyl 2-acetoxypropionate thus obtained may be isolated or purified by any suitable method, such as distillation, e.g. vacuum distillation. Some methods of preparing a bio-based acrylic material, such as acrylic acid or butyl acrylate, include heating methyl 2-acetoxypropionate to form methyl acrylate.

For some reactions, methyl 2-acetoxypropionate is pyrolyzed to methyl acetate over SiC. In some examples, the exposure to SiC may occur at 450 °C to 650 °C, e.g., 550 °C. In some cases, the exposure to SiC may be under a carbon dioxide (CO2) atmosphere. Some embodiments include the addition of an inhibitor to the crude methyl acrylate product solution.

The methyl acetate thus obtained may be isolated or purified by any suitable method, such as distillation, e.g. vacuum distillation.

Some methods of preparing a bio-based acrylic material include reacting a mixture comprising methyl acrylate, n-butanol, and an acid catalyst (such as toluenesulfonic acid), optionally with heating, to form butyl acrylate.

For a conversion of methyl acrylate to butyl acrylate, the acid catalyst may be a strong acid. In some embodiments, the strong acid may be an organic acid. In some examples, the strong acid may be a sulfonic acid. In some embodiments, the strong acid may be p-toluenesulfonic acid (also referred to as p-TsOH, TsOH or tosic acid).

For a conversion of methyl acrylate to butyl acrylate, the molar ratios of the respective reactants may be about 1 -5 moles of methyl acrylate (e.g. about 1 -2 moles, about 2-3 moles, about 3-4 moles, or about 4-5 moles of methyl acrylate) to about 0.5- 2 moles of butanol (e.g. about 0.5-1 moles, about 1-1.5 moles, or about 1.5-2 moles of butanol) to about 0.001-0.5 moles of TsOH (e.g. about 0.001-0.01 moles, about 0.01-0.1 moles, or about 0.1-0.5 moles of TsOH), e.g., about 3 moles of methyl acrylate to about 1 mole of butanol to about 0.01 mole of TsOH.

A reaction mixture comprising methyl acrylate, n-butanol, and an acid catalyst (such as p-toluenesulfonic acid), may optionally be heated. In some embodiments, the reaction temperature is maintained between about 100 °C to about 130 °C, e.g., about 115 °C. In some embodiments, the heated reaction mixture may be stirred for about 8 to about 24 hours, e.g., about 18 hours.

Transesterification of methyl acrylate with n-butanol may produce butyl acrylate and methanol. Methanol forms an azeotropic mixture with methyl acrylate. As a result, in some embodiments, the first distillation fraction to be removed from the transesterification of methyl acrylate and n-butanol is this azeotropic mixture of methyl acrylate and methanol (also referred to herein as “azeotropic distillate”). Removal of the azeotropic mixture drives the conversion of n-butanol to butyl acrylate, but requires excess methyl acrylate. Thus, the azeotropic mixture of methanol and methyl acrylate may be first removed, followed by distillation of the excess methyl acrylate.

In some embodiments, the azeotropic distillate comprises greater than 25% v/v methyl acrylate. In other embodiments, the azeotropic distillate may comprise greater than 30%, greater than 33%, greater than 40, greater than 45%, greater than 50%, about 33%, or about 50% v/v methyl acrylate.

Acrylic acid may be recovered from the azeotropic distillate by saponifying (also referred to herein as hydrolyzing) the azeotropic distillate with a strong base to generate a basic saponified distillate containing an acrylate salt. In some embodiments, the method comprises neutralizing the acrylate salt with a strong acid to generate an acrylic acid product. In some embodiments, the method comprises extracting the acrylic acid product with a polar solvent. In other embodiments, the extracted acrylic acid product is further purified by distillation.

In some embodiments, the methyl acrylate reactant may comprise methyl acrylate ora methyl acrylate/methanol azeotrope. In some embodiments, saponifying the methyl acrylate reactant comprises adding a strong base. In some embodiments, the strong base may be a base having a pKa of greater than 15.7. In some examples, the strong base may be sodium hydroxide or potassium hydroxide. In some embodiments, sufficient strong base is added to raise the pH of the reactant solution to about pH 10.0 to about 15.0, e.g., about 14. In some embodiments, the strong base may be pre-chilled to about 1-20 °C, e.g., about 10 °C.

The acrylate salt formed by saponifying the azeotropic mixture may be neutralized with an acid, such as a strong acid, to obtain acrylic acid. In some embodiments, the strong acid may be an acid having a pKa of less than -6. Some examples of a strong acid are sulfuric acid (H2SO4), phosphoric acid (H3PO4), and/or hydrochloric acid (HCI). In some embodiments, sufficient strong acid is added to the saponified reactant mixture to lower the pH of the reactant solution to about pH 6.0 to about 8.0, e.g., about 7.0. In some cases, the strong acid may be pre-chilled to about 1-20 °C, e.g., about 10 °C.

In some embodiments, the method for making acrylic acid may comprise extracting the neutralized methyl acrylate reactant mixture with a polar solvent. In some embodiments, the polar solvent may be a polar aprotic solvent, such as a polar aprotic solvent that is immiscible with water. In some embodiments, the polar solvent may have a dielectric constant of greater than 5.0. In some embodiments, the polar solvent may have a dipole moment of greater than 1.50 D. In some embodiments, the polar solvent may be dichloromethane (DCM), chloroform, diethyl ether, ethyl acetate, cyclohexane, toluene and/or combinations thereof. In some examples, the polar solvent is dichloromethane. In other examples, the polar solvent is ethyl acetate.

In some embodiments, the azeotropic distillate of bio-based methyl acrylate and methanol is prepared through the reaction of bio-based methyl acrylate with butanol as described above. While the method described herein for bio-based acrylic acid and bio-based butyl acrylate production from bio-based methyl acrylate is a preferred embodiment, the method may also be used for petroleum-based methyl acrylate.

In some embodiments, the method of making bio-based acrylic acid comprises starting material methyl lactate. In some examples, methyl lactate may be purchased from a commercial vendor. In other embodiments, the methyl lactate may be used without further purification. In some cases, methyl lactate may be synthesized from lactic acid. In some embodiments, methyl lactate may be synthesized from a lactic acid salt and methanol by any suitable procedure. In some embodiments, the lactic acid salt may be calcium lactate, sodium lactate or mixtures thereof. In some embodiments, the methyl lactate may be purified by aqueous extraction. In other embodiments, the methyl lactate may be purified by distillation. Some embodiments include purifying the methyl lactate by distillation after aqueous extraction. In some embodiments, methyl lactate may be synthesized from ammonium lactate present in a fermentation broth.

In some embodiments, methyl acrylate may be purchased from a commercial vendor. In some examples, methyl acrylate may be synthesized from methyl lactate as described herein. In some embodiments, the methyl lactate reactant may be bio- based. Some embodiments include the conversion of methyl lactate to methyl 2- acetoxypropionate, which in turn is converted into methyl acrylate by pyrolysis over silicon carbide (SiC).

In some embodiments, the starting materials and products described herein are bio-based. In some examples, the amount of originating bio-sourced material may be greater than about 89%, greater than about 90%, greater than about 95%, or greater than about 99% bio-based carbon. The percentage of bio-based carbon may be determined by any suitable method. For example, the result may be obtained using the radiocarbon isotope (also known as Carbon-14, C14 or 14C), a naturally occurring isotope of carbon that is radioactive and decays in such a way that there is none left after about 45,000 years following the death of a plant or animal. The current active standard is ASTMD6866-20, although different standards may be used worldwide.

The analytical procedures for measuring radiocarbon content using the different standards are identical, the only difference being reporting format. Results are usually reported using the standardized terminology “% biobased carbon.” Only ASTM D6866 uses the term “% biogenic carbon” when the result represents all carbon present (Total Carbon) rather than just the organic carbon (Total Organic Carbon). The terms “% biobased carbon” and “% biogenic carbon” are now the standard units in regulatory and industrial applications, replacing obscure units of measure historically reported by radiocarbon dating laboratories (e.g., disintegrations per minute per gram (dpm/g) or radiocarbon age).

The bio-based carbon result may be obtained by measuring the ratio of radiocarbon in the material relative to a National Institute of Standards and Technology (NIST) modern reference standard (SRM 4990C). This ratio may be calculated as a percentage and may be reported as percent modern carbon (pMC). The value obtained relative to the NIST standard may be normalized to the year 1950 AD so an adjustment was required to calculate a carbon source value relative to today. A value of 100% bio-based or biogenic carbon would indicate that 100% of the carbon came from plants or animal by-products (biomass) living in the natural environment and a value of 0% would mean that all of the carbon was derived from petrochemicals, coal and other fossil sources. A value between 0-100% would indicate a mixture. The higher the value, the greater the proportion of naturally sourced components in the material.

Exemplary but non-limiting embodiments are as follows:

Embodiment 1. A method for making acrylic acid comprising: providing an azeotropic distillate comprising methanol and methyl acrylate, wherein the azeoptropic distillate comprises greater than 33% v/v methyl acrylate; saponifying the azeotropic distillate with a strong base to generate a basic saponified distillate; neutralizing the basic saponified distillate with a strong acid to generate an acrylic acid product; and extracting the acrylic acid product with a polar solvent.

Embodiment 2. The method of embodiment 1 , wherein pure methyl acrylate is further provided.

Embodiment 3. The method of embodiment 1 , wherein the strong base of the saponifying step comprises sodium hydroxide.

Embodiment 4. The method of embodiment 3, wherein the sodium hydroxide is pre-chilled to about 1-10 °C.

Embodiment 5. The method of embodiment 1 wherein the strong acid comprises at least hydrogen chloride (HCI).

Embodiment 6. The method of embodiment 5, wherein the strong acid is pre-chilled to about 1-10 °C.

Embodiment 7. The method of embodiment 1 , wherein the polar solvent can be dichloromethane.

Embodiment 8. The method of embodiment 1 or 2 wherein providing as azeoptropic distillate comprises providing a bio-based methyl lactate starting material; converting the bio-based methyl lactate material into a bio-based methyl 2- acetoxypropionate ; and converting the bio-based methyl 2-acetoxypropionate into a bio-based methyl acrylate solution.

Embodiment 9. The method of embodiment 8, wherein the conversion of bio-based methyl lactate into a bio-based methyl 2-acetoxypropionate comprises mixing bio-based methyl lactate with acetic anhydride (AC2O) in the presence of Amberlyst (H-form) resin for a period of about 10-20 hours and distilling the resultant bio-based methyl 2-acetoxypropionate product solution.

Embodiment 10. The method of embodiment 9, wherein the bio-based methyl lactate is between 25 -75 molar % and the acetic anhydride is between 75- 25 mol%.

Embodiment 11. The method of embodiment 8, wherein converting the methyl 2-acetoxypropionate comprises passing the distilled bio-based methyl 2- acetoxypropionate via a carbon dioxide carrier over Silicon Carbide (SiC) at a high temperature (between 500 to 600 °C, preferably between 550 - 560 °) to make a biobased methyl acrylate.

Embodiment 12. The method of embodiment 1 , wherein the azeotropic distillate is a by-product of a butyl acrylate synthetic process.

Embodiment 13. The method of embodiment 12, wherein the butyl acrylate synthetic process comprises providing a precursor solution of methyl acrylate and n- butyl alcohol, wherein at least 2 (3) molar equivalents of methyl acrylate are provided for each molar equivalent of n-butyl alcohol.

Embodiment 14. The method of embodiment 13, wherein the butyl acrylate synthetic process comprises mixing methyl acrylate and n-butanol in the presence of p-toluenesulfonic acid (Tosic acid/TsOH).

Embodiment 15. A bio-based acrylate monomer made according to embodiments 1-10.

EXAMPLES

I. Synthesis of Bio-Based Acrylic Acid Example 1.

Synthesis of Methyl 2-Acetoxypropionate.

In a 1 L round bottom flask was placed methyl lactate (200 mL, 2.1 mol, CAS 27871-49-4) and Amberlyst 15 (H) resin (3 g, CAS 39389-20-3). The reaction mixture was cooled to 0°C and then acetic anhydride (198 mL, 2.1 mol, CAS 108-24-7) was added slowly via addition column to avoid exothermic reaction. The reaction mixture was stirred at room temperature for 18 h, then the solution was filtered to remove the Amberlyst resin using diethyl ether (50 mL) as a rinse. Diethyl ether was removed through evaporation and the crude product was purified via fractionating vacuum distillation. Methyl 2-acetoxypropionate was isolated at 55-58°C of vapors and 7-9 mmHg vacuum pressure as a colorless and transparent liquid (277 g, 90%, with ~4% residual acetic acid). 1 H NMR (400 MHz, Chloroform-d) d 5.09 (q, J = 7.1 Hz, 1 H), 3.75 (s, 3H), 2.13 (s, 3H), 1.49 (d, J = 7.1 Hz, 3H).

Example 2.

Synthesis of Methyl Acrylate from Methyl 2-Acetoxypropionate.

A quartz tube (74 cm in length, 25 mm ID, 28 mm OD) was packed with 250 g of silicon carbide boiling chips, using enough to fill the bottom 30 cm of the quartz tube. The tube was positioned vertically and wrapped with 2 separately controlled heating tapes (~30 cm length sections at the top and bottom), fitted with a 60 mL addition funnel, at the top and a 2-neck 250 mL round-bottom flask at the bottom. The second neck of the round-bottom flask was fitted with a glass adapter and reflux condenser. A gas inlet adapter was placed on the addition funnel, and the outlet of the condenser was attached to a bubbler, allowing a constant flow of carbon dioxide throughout the reaction. The quartz tube was heated to 170°C for the top 30 cm section and 550°C for the bottom 30 cm section, a stream of CO2 was flowed through the system at a rate of 0.15 LPM, the round-bottom flask was kept cool throughout the reaction by immersion in dry ice, and the reflux condenser was cooled with room temperature water. After stabilization of the pyrolysis tube at 170°C and 550°C for 30 minutes, methyl 2-acetoxypropionate (145.8 g, 1.00 mol) was added dropwise in 60 mL fractions at a rate of 1 drop per 1-3 seconds. Afterthe final addition, MEHQ was added to the yellow liquid that had condensed in the round-bottom flask, and the liquid was allowed to warm to 25°C under ambient conditions. The product was purified via vacuum distillation over a temperature range of 60-85°C and vacuum pressure of 24- 25 inHg yielding a colorless liquid of mass 65.13 g, 76% yield. 1 H NMR (400 MHz, Chloroform-d) d 6.41 (d, J = 17.3 Hz, 1 H), 6.13 (dd, J = 17.3, 10.4 Hz, 1 H), 5.83 (d, J = 11.9 Hz, 1 H), 3.76 (s, 3H). The product was stored at room temperature after addition of MEHQ.

Example 3.

Synthesis of Butyl Acrylate from Methyl Acrylate.

TsOH

112°C; 18h; distillation

In a 500 mL round bottom flask were combined methyl acrylate (135 mL, 1.5 mol, Example 2), n-butanol (46 mL, 0.5 mol, Bio-based, Green Biologies Ltd.); p- toluenesulfonic acid monohydrate (0.95 g, 0.005 mol, CAS 6192-52-5) and hydroquinone (2 g, 0.018 mol) was used as an inhibitor. This reaction mixture was heated by oil bath at 115°C with a 24-28 cm fractionation column (vigreux type) to distill out an azeotropic mixture of formed methanol and methyl acrylate (bp = 63°C) into an attached round bottom flask. After 18 h no additional formation of azeotropic distillate was observed, which yielded 57 g of 50% MeOH in methyl acrylate mixture (1 :1 mol ratio by NMR analysis). The reaction mixture was cooled to room temperature and the excess methyl acrylate was distilled out without vacuum at 135°C (35-45°C vapors). After cooling to room temperature, fractional vacuum distillation was conducted on the remaining mixture. A 98% pure butyl acrylate (38.2 g, 60%) was isolated as a colorless and transparent liquid at 40-42°C of vapors and 15-16 mmHg vacuum pressure. The mixed fractions containing n-butanol and butyl acrylate were re-distilled or re-used in the same synthesis as an addition to the pure components of the reaction mixture. 1 H NMR (400 MHz, Chloroform-d) d 6.29 (dd, J = 17.4; 1.6 Hz, 1 H), 6.02 (dd, J = 17.3; 10.4 Hz, 1 H), 5.70 (dd, J = 10.4; 1.6 Hz, 1 H), 4.06 (t, J = 6.7 Hz, 2H), 1 .49 - 1.62 (m, 2H), 1.23 - 1.38 (m, 2H), 0.84 (t, J = 7.4 Hz, 3H).

Biobased carbon content = 100%. Laboratory Number Beta- 555313 Percent modern carbon fpMC) 100.03 +/- 021 pMC Atmospheric adjustment factor (REF) 100.0; = pMC/1.000

Example 4.

Synthesis of Butyl Acrylate from Methyl Acrylate with 1 :2 molar ratio of starting material components.

Butyl acrylate was prepared according to the procedure described in example 3 from bio-based n-butanol (46 mL, 0.5 mol) and methyl acrylate (86 g, 1 mol), p- toluenesulfonic acid monohydrate (0.95 g, 0.005 mol, CAS 6192-52-5) and hydroquinone (2 g, 0.018 mol) was used as an inhibitor. After fractional distillation of the crude reaction mixture 32 g of butyl acrylate was obtained (50%, purity 96%).

Example 5.

Synthesis of Butyl Acrylate from Recycled Materials.

Butyl acrylate was prepared according to the procedure described in example 3 from bio-based n-butanol (46 mL, 0.5 mol), p-toluenesulfonic acid monohydrate (0.95 g, 0.005 mol, CAS 6192-52-5), hydroquinone (2 g, 0.018 mol) as an inhibitor and methyl acrylate (138 g, 1.5 mol) as recycled mixed fractions isolated after distillation from previous reactions and contained mostly methyl acrylate, -20% n-butanol, -10- 20% methanol and traces of butyl acrylate. After fractional distillation of the crude reaction mixture 40 g of butyl acrylate was obtained (63%, purity 96%).

Example 6.

Synthesis of Acrylic Acid from Methyl Acrylate.

Hydrolysis of Bio-Based Methyl Acrylate with DCM Extraction Procedure.

To a 25 mL sodium hydroxide solution (7.2 M, 180 mmol) at 4 °C was added methyl acrylate (16.6 mL, 180 mmol) under vigorous stirring. The reaction was stirred at room temperature until completely homogenize resulting in a colorless turbid solution. After approximately 25 minutes a rapid exotherm is observed, the solution clarifies, and after cooling to 0 °C the reaction mixture was treated with a pre-chilled 6 M HCI solution (30 mL, 180 mmol). A conversion of 100% and acrylic acid selectivity of 92% was determined via NMR analysis. The obtained solution was stirred at room temperature for one hour and then extracted with dichloromethane (3x80 mL) and dried over anhydrous sodium sulfate. Vacuum distillation with 100 mg phenothiazine as inhibitor at 10 mmHg at 28°C of vapors yields 73.1 % of acrylic acid (>99% acrylic acid, <1% other). Biobased carbon content is 96%. 1 H NMR (400 MHz, Chloroform- d) 5 6.52 (d, J = 17.3 Hz, 1 H), 6.14 (dd, J = 17.6, 10.8 Hz, 1 H), 5.96 (d, J = 10.8 Hz, 1 H).

Example 7.

Hydrolysis of Bio-Based Methyl Acrylate with EtOAc Extraction Procedure.

To a 25 mL sodium hydroxide solution (7.2 M, 180 mmol) at 4°C was added methyl acrylate (16.6 mL, 180 mmol) under vigorous stirring. The reaction was stirred at room temperature until completely homogenize resulting in a colorless turbid solution. At approximately 25 minutes a rapid exotherm is observed, the solution clarifies, and after cooling on ice bath the reaction mixture was treated with a prechilled 6 M HCI solution (30 mL, 180 mmol). A conversion of 100% and acrylic acid selectivity of 93% was determined via NMR analysis. The solution was stirred at room temperature for one hour, then extracted with ethyl acetate (3x100 mL) and dried over anhydrous sodium sulfate. Vacuum distillation with 100 mg phenothiazine as inhibitor was conducted at 10 mmHg at28°C of vapors and yields 62.2% of acrylic acid (97.1% acrylic acid, 1.9% methyl-3-hydroxypropionate, 1% ethyl acetate).

Example 8.

Hydrolysis of Bio-Based Methyl Acrylate (50% in Methanol) from azeotropic mixture with EtOAc Extraction Procedure.

To a 50 mL sodium hydroxide solution (7.2 M, 360 mmol) at 4°C was added a methyl acrylate (43.26 g, 360 mmol; 50% solution in methanol), as an azeotropic mixture obtained in Example 3, under vigorous stirring. The reaction was stirred at room temperature until completely homogenize resulting in a colorless turbid solution. The solution clarifies in 5-10 minutes following a rapid exotherm. After cooling on ice bath the reaction mixture was treated with the addition of a pre-chilled aqueous 6 M HCI (60 mL, 360 mmol). A conversion of 100% and acrylic acid selectivity of 85% was determined via NMR analysis. After stirring at room temperature for 30 minutes, acrylic acid is extracted with ethyl acetate (3x100 mL) and the combined organic layers dried over anhydrous sodium sulfate. Vacuum distillation with 100 mg phenothiazine as inhibitor yields at 10 mmHg and 28°C of vapors of acrylic acid (67.6% yield; 95% acrylic acid, 1.3% ethyl acetate, 3.7% acetic acid).

Example 9.

Hydrolysis of Bio-Based Methyl Acrylate (33% in Methanol) from azeotropic mixture with EtOAc Extraction Procedure.

To a 40.2 mL sodium hydroxide solution (7.2 M, 289 mmol) at 4°C was added a 33% methyl acrylate (36.39 g, 289 mmol) solution in methanol (azeotropic mixture) under vigorous stirring. The reaction was stirred at room temperature until completely homogenize resulting in a colorless turbid solution. The solution clarifies in 4 minutes following a rapid exotherm. After cooling on ice bath the reaction mixture was treated with addition of a pre-chilled aqueous 6 M HCI (48.2 mL, 289 mmol). A conversion of 100% and acrylic acid selectivity of 75.8% was determined via NMR analysis. After stirring at room temperature for 30 minutes, acrylic acid is extracted with ethyl acetate (3x100 mL) and the combined organic layers dried over anhydrous sodium sulfate. Vacuum distillation with 100 mg phenothiazine as inhibitor yields at 10 mmHg and 28°C of vapors of acrylic acid (49% yield; 94% acrylic acid, 1 % methyl-3- hydroxypropionate, 5% acetic acid).

Example 10.

Determination of bio-based content

Analytical procedure for determination of bio-based content according to ASTM 6866-18, Method B by Beta Analytic test laboratory (Miami, FL, USA):

The provided sample material did not undergo any pre-treatment procedure and was converted to graphite as was using the following procedure.

Depending on the estimated amount of carbon content, typically a few milligrams of sample material was being combusted in an Elemental Analyzer (EA). The resulting gas mixture was being cleaned and CO₂ was automatically separated by the EA using the purge and trap technology.

The remaining CO₂ was transferred into a custom-made graphitization system, converted into carbon (graphite) catalytically using H2 and an iron-powder catalyst.

The carbon-14 determination of the graphite derived from acrylic acid made herein was performed at Beta Analytic (Miami, FLA, USA).

Laboratory Number Beta-555314

Percent modern carbon fpMC) 95.75 +/- 0.2 pMC Atmospheric adjustment factor (REF) 100.0; = pMC/1 .000

The carbon-14 determination of the graphite derived from the butyl-acrylate made herein was performed at Beta Analytic (Miami, FLA, USA).

Laboratory Number Beta-555313

Percent modern carbon {pMC) 100.03 +/- 0.21 pMC

Atmospheric adjustment factor (REF) 100.0; = pMC/1.000

Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

The terms “a,” “an,” “the” and similar referents used in the context of describing the disclosure (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. All methods described herein may be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein is intended merely to better illuminate the disclosure and does not pose a limitation on the scope of any claim. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the present disclosure.

Groupings of alternative elements or embodiments disclosed herein are not to be construed as limitations. Each group member may be referred to and claimed individually or in any combination with other members of the group or other elements found herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

Certain embodiments are described herein, including the best mode known to the inventors for carrying out the present disclosure. Of course, variations on these described embodiments will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventors intend for the present disclosure to be practiced otherwise than specifically described herein. Accordingly, the claims include all modifications and equivalents of the subject matter recited in the claims as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is contemplated unless otherwise indicated herein or otherwise clearly contradicted by context.

In closing, it is to be understood that the embodiments disclosed herein are illustrative of the principles of the claims. Other modifications that may be employed are within the scope of the claims. Thus, by way of example, but not of limitation, alternative embodiments may be utilized in accordance with the teachings herein. Accordingly, the claims are not limited to embodiments precisely as shown and described.

Claims

1. A method for making acrylic acid, comprising: acetylation of methyl lactate to provide methyl 2-acetoxypropionate.

2. A method for making acrylic acid, comprising: reacting methyl acrylate with n-butanol to form butyl acrylate and methanol while leaving unreacted methyl acrylate in the reaction mixture; distillation of the reaction mixture to provide an azeotropic mixture of the methanol and the unreacted methyl acrylate; further distillation of the reaction mixture to obtain butyl acrylate; and hydrolysis of the azeotropic mixture of methanol and methyl acrylate to obtain acrylic acid.

3. A method for making acrylic acid, comprising: acetylation of methyl lactate to provide methyl 2-acetoxypropionate; pyrolysis of methyl 2-acetoxypropionate to provide methyl acrylate; reacting the methyl acrylate with n-butanol to form butyl acrylate and methanol while leaving unreacted methyl acrylate in the reaction mixture; distillation of the reaction mixture to provide an azeotropic mixture of the methanol and the unreacted methyl acrylate; further distillation of the reaction mixture to obtain butyl acrylate; and hydrolysis of the azeotropic mixture of methanol and methyl acrylate to obtain acrylic acid.

4. The method of claim 1 or 3, wherein acetylation of methyl lactate comprises mixing methyl lactate with acetic anhydride in the presence of an acidic resin for a period of about 10-20 hours, followed by distillation to provide methyl 2- acetoxypropionate.

5. The method of claim 3 or 4, wherein pyrolysis comprises passing methyl 2- acetoxypropionate over silicon carbide at a temperature of about 500-600 °C under a CO2 atmosphere, followed by distillation to provide methyl acetate.

6. The method of claim 2, 3, 4, or 5, wherein the azeotropic mixture of methanol and methyl acrylate comprises greater than 33% v/v methyl acrylate.

7. The method of claim 2, 3, 4, 5, or 6, wherein hydrolysis comprises: treating the azeotropic mixture of methanol and methyl acrylate with a strong base; neutralizing with a strong acid; extraction with a polar solvent to provide a crude acrylic acid product; addition of an inhibitor; and vacuum distillation to obtain an acrylic acid product.

8. The method of claim 7, wherein the strong base is sodium hydroxide.

9. The method of claim 7 or 8, wherein the strong acid is hydrogen chloride.

10. The method of claim 7, 8, or 9, wherein the polar solvent is ethyl acetate.

11. The method of claim 7, 8, or 9, wherein the polar solvent is dichloromethane.

12. The method of claim 7, 8, 9, 10, or 11 , wherein the acrylic acid product is greater than 90% pure.

13. The method of claim 12, wherein the acrylic acid product is greater than 95% pure.

14. The method of claim 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, or 13, wherein the butyl acrylate has a bio-based carbon content of greater than 95%.

15. The method of claim 14, wherein the butyl acrylate has a bio-based carbon content of greater than 99%.

16. The method of any one of claims 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, or 15, wherein the acrylic acid has a bio-based carbon content of greater than 95%.

17. The method of claim 16, wherein the acrylic acid has a bio-based carbon content of greater than 99%.