Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C41/00—Preparation of ethers; Preparation of compounds having groups, groups or groups
  • C07C41/01—Preparation of ethers
  • C07C41/16—Preparation of ethers by reaction of esters of mineral or organic acids with hydroxy or O-metal groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C43/00—Ethers; Compounds having groups, groups or groups
  • C07C43/02—Ethers
  • C07C43/03—Ethers having all ether-oxygen atoms bound to acyclic carbon atoms
  • C07C43/14—Unsaturated ethers
  • C07C43/15—Unsaturated ethers containing only non-aromatic carbon-to-carbon double bonds
  • C07C43/16—Vinyl ethers
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C67/00—Preparation of carboxylic acid esters
  • C07C67/08—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C68/00—Preparation of esters of carbonic or haloformic acids
  • C07C68/06—Preparation of esters of carbonic or haloformic acids from organic carbonates
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C69/00—Esters of carboxylic acids; Esters of carbonic or haloformic acids
  • C07C69/02—Esters of acyclic saturated monocarboxylic acids having the carboxyl group bound to an acyclic carbon atom or to hydrogen
  • C07C69/12—Acetic acid esters
  • C07C69/16—Acetic acid esters of dihydroxylic compounds
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C69/00—Esters of carboxylic acids; Esters of carbonic or haloformic acids
  • C07C69/96—Esters of carbonic or haloformic acids
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
  • C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
  • C07D307/04—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having no double bonds between ring members or between ring members and non-ring members
  • C07D307/10—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having no double bonds between ring members or between ring members and non-ring members with substituted hydrocarbon radicals attached to ring carbon atoms
  • C07D307/12—Radicals substituted by oxygen atoms
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
  • C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
  • C07D307/34—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
  • C07D307/38—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with substituted hydrocarbon radicals attached to ring carbon atoms
  • C07D307/40—Radicals substituted by oxygen atoms
  • C07D307/42—Singly bound oxygen atoms

Definitions

• the present invention relates to a method for converting biologically-derived glycols into useful products.
• the invention pertains to a simple and green process of synthesizing a variety of compounds from alkylene glycols or furanic diols.
• glycol ethers are one of the most versatile classes of organic solvents. These molecules combine the best solvency features of alcohols and ethers, which allows for good miscibility and solvency in a wide range of organic chemicals and oils, as well as solubility in water. Glycol ethers also have higher boiling points. For these reasons, glycol ethers are prominent in the (i) surface coating industry as active solvents for resins, (ii) brake fluid industry as solvents, (iii) petroleum industry as anti-icers in various petroleum based fuels, (iv) automotive industry as antifreezes, and (v) specialty products for use in household goods.
• glycol ethers are labeled either “e-series” or “p-series” glycol ethers, depending on whether they are made from ethylene or propylene, respectively.
• e-series glycol ethers are found in pharmaceuticals, sunscreens, cosmetics, inks, dyes and water based paints, while p-series glycol ethers are used in degreasers, cleaners, aerosol paints and adhesives.
• E-series glycol ethers are higher in molecular weights, and can be used as intermediates that undergo further chemical reactions.
• P-series glycol ethers are generally high performance industrial solvents.
• glycol ethers have conventionally involved the generation of an alkylene oxide. For instance, one can react ethylene oxide (EO) or propylene oxide (PO) with alcohols in the e-series and p-series respectively.
• the glycol ether molecules can contain one or more EO or PO molecule in them.
• Typical alcohols used include methanol, ethanol, propanol, butanols, pentanols and hexanols. This reaction can produce glycol ethers of varying chain length depending on the molar ratio of reactions and temperature and pressures used in the reaction.
• the alkylene oxide can be synthesized by hydration of the alkylene with hypochlorous acid followed by base catalyzed epoxidation or by direct epoxidation of the alkylene with i-butyl hydroperoxide.
• glycol ethers can be produced by the reaction of an alcohol with an olefin oxide in the presence of an acidic or basic catalyst.
• U.S. Patent No. 6,124,506 describes an another process of glycol ether synthesis which involves reacting an olefin oxide with an alcohol over a catalyst comprising a layered double hydroxide (LDH) clay with its layered structure intact and having interlamellar anions, at least some of which are metal anions or (poly)oxometallate anions.
• LDH layered double hydroxide
• U.S. Patent No. 8,748,635 B2 describes a method for the preparation of anhydrosugar ethers by alkylation of anyhydrosugar alcohols using a solid phase zeolite catalyst.
• Alkylene glycols can be generated by diverse processes. For instance, in one pathway, one subjects glucose to hydrogenation and hydrogeno lysis to generate propylene glycol (PG) or ethylene glycol (EG). In another pathway, one ferments glucose to produce ethanol and CO2. Ethanol is then converted to ethylene oxide with a silver catalyst, which then reacts with CO2 to form cyclic ethylene carbonate, which generates a corresponding dialkyl carbonate when reacted with an alcohol. In the dehydration/reduction step to make epoxides one requires an additional reaction step. These processes all involve multiple steps that both add to the complexity and costs of producing the desired product.
• the present disclosure relates to a method of preparing a mono-ether from a diol compound, comprising either a first pathway or second pathway.
• the diol compound contacts an R 1 organic acid in the presence of a Bronsted acid at a temperature and for time sufficient to form a R 1 mono ester of the diol compound, then the R 1 mono ester of the diol compound contacts a R 2 alkyl diester of the formula R 2 (COs)R 2 in the presence of a deprotonating agent at a temperature and for a time sufficient to form the monoester ether.
• the diol compound contacts the an R 2 alkyl diester of the formula R 2 (COs)R 2 in the presence of a deprotonating agent at a temperature and for a time sufficient to form a mono ester of the diol compound, then the mono ester of the diol compound contacts an R 1 organic acid in the presence of a Bronsted acid at a temperature and for time sufficient to form the monoester ether.
• the R 1 and R 2 are either the same or different alkyl, cyclo-alkyl or aromatic moieties.
• FIG. 1 is a general schematic showing two synthesis pathways in preparing etherified or acetylated diols from an alkylene diol.
• FIG. 2 is a schematic of a reaction according to an embodiment of the present method, which shows propylene glycol and propylene glycol-acetate alkyl etherification.
• FIG. 3 is a schematic of a reaction according to another embodiment of the present method, which shows FDM and FDM acetate alkyl etherification.
• FIG. 4 is a schematic of a reaction according to an alternate embodiment of the present method, which shows bHMTHFs and alkyl etherification of bHMTHF acetates.
• FIG.5 is a schematic of a reaction according to another embodiment of the present method, which exhibits the synthesis of alkylene glycol carbonates.
• FIG.6 is a schematic of a reaction according to another embodiment of the present method, which reveals the synthesis of FDM carbonates
• FIG 7 is a schematic of a reaction according to another embodiment of the present method, which demonstrates the synthesis of bHMTHF carbonates.
• the present synthesis method provides a simple, clean and elegant process for preparing ethers and/or acetates directly from alkyl or furanic diols without need to either dehydrate or reduce the starting materials from renewable, bio-based materials.
• the present method involves reacting an alkyl glycol with a solution of a dialkyl-carbonate reagent in the presence of a deprotonating agent, and in substantial absence of any other extrinsic catalyst.
• substantial absence refers to a condition in which an extrinsic catalyst is either largely or completely absent, or is present in de minimis or trace amount of less than catalytic efficacy. In other words, no extrinsic catalyst is present, or is present at a level less than 5%, 3%, or 1% weight/weight relative to the amount of dialkyl- carbonate reagent in the reaction.
• the method can be used to make mono-ethers, mono-esters, and alkoxy-esters from renewable alkylene, alkyl or furanic diols without need to either oxidize to form oxides or dehydrate and reduce to form epoxides.
• diols are glycols such as ethylene glycol (EG), propylene glycol (PG), and 2,3-butane diol (BDO).
• the reactant materials may be ethylene glycol mono-acetate, propylene glycol mono-acetate, or a mixture thereof.
• the furanic diol reactant can be the reduced analogs of HMF - furan-2,-5-dimethanol (FDM), and/or 2,5-fe-hydroxymethyl- tetrahydro-furan (bHMTHF).
• FDM furan-2,-5-dimethanol
• bHMTHF 2,5-fe-hydroxymethyl- tetrahydro-furan
• glycol mono-ethers are synthesized according to a base-mediated process.
• mono-acetates, or ether-acetates or glycol, mono- or dicarbonates are prepared directly from alkylene glycol precursors in a simple, direct fashion using alkyl-carbonate as an alkylating agent and/or acid-catalyzed Fischer acetylation.
• the method also enables one to selectively prepare ethers, acetates, aggregate ether-acetates, mono-carbonates and di-carbonates from furanic diols.
• the mono-ether is the favored and predominant product resulting from the reaction.
• Figure 1 represents a schematic of two alternate pathways according to the present invention for preparing a glycol mono-ether or mono-acetate ester. Both pathways will enable one to generate either ether or acetate products.
• first pathway one reacts either an alkylene glycol with a solution of a dicarbonate reagent in the presence of a deprotonating agent, in substantial absence of an extrinsic catalyst, to produce an ether, and subsequently acetylating the ether with an acid, base or enzymatic catalyst.
• one reacts the alkylene glycol with an acetate donor in the presence of an acid, base, or enzymatic catalyst to generate an alkylene mono-acetate, and then etherifying with a carbonate in the presence of a deprotonating agent or base.
• one reacts an ether product of the first pathway or acetate product of the second pathway with a carbonate containing C3 chains or higher, allyl, phenyl, or benzyl, to produce a mono-carbonate or dicarbonate or both.
• the alkylene glycol when starting with an alkylene glycol according to the first pathway, one will generate an ether in a first step. Alternatively, one will make an acetate in the first step in the other second pathway.
• the alkylene glycol contacts a dialkylcarbonate reagent in the presence of a deprotonating agent in substantial absence of an extrinsic catalyst to produce ethers.
• a deprotonating agent in substantial absence of an extrinsic catalyst
• one acetylates the ether product with either an acid (e.g., acetic acid) as shown, or alternatively with a base (e.g., any alkoxide base - methoxide), or enzymatic catalyst.
• alkylene glycols are reacted with an acetate donor (e.g., free acid, anhydride, ether) in the presence of a mineral acid (alternatively a base or enzymatic catalyst) to generate an alkylene mono-acetate, which is then etherified with a carbonate in the presence of a deprotonating agent or base.
• an acetate donor e.g., free acid, anhydride, ether
• a mineral acid alternatively a base or enzymatic catalyst
• the intermediate ether or acetate product is, respectively, acetylated or etherified to a final product.
• the dialkyl-carbonate reagent can have an R-group with 1 to 20 carbon atoms.
• R- group is a methyl, ethyl, propyl group
• an ether is usually the product of the reaction.
• R- group is a C4-C20 group
• a mono-alkylcarbonate is generated.
• the larger or more bulky R-moiety tends to promote the formation of a mono-alkylcarbonates.
• the etherifying agent contains an R- group that is an allyl, phenyl, or benzyl moiety or has C4 or greater chain, the product tends to be a mono- or dialkyl-carbonate or a mixture of both.
• the reaction is assisted by a deprotonating agent or a proton acceptor such as a Bronsted base.
• Various proton acceptors may include, for example, at least one of the following: calcium, potassium or sodium carbonate, an amine, ammonia, etc.
• the mineral carbonates in particular, exhibit low solubility in the reactor medium, which makes the carbonates easier to separate from the final products in downstream processing.
• the pathways can be inverted, i.e., the glycol can be mono-acetylated first, then etherified in the aforementioned manner.
• the etherification occurs without an extrinsic catalyst, but by merely deploying a Bronsted base to facilitate the alkylation.
• the Bronsted base has a pKa of at least 4, which assists the -OH deprotonatation of the polyol.
• the amount of dialkyl-carbonate reagent employed in the reaction can be in an amount of at least one (1) to about three (3) stoichiometric equivalents per alkylene glycol molecule.
• the amount of dialkyl-carbonate reagent is present at about two (2) stoichiometric equivalents per hydroxyl (OH) group of the alkyl diol.
• the carbonate reagent can be one of the functional groups: mono- propyl, mono-butyl, mono-pentyl, mono-hexyl, mono-benzyl, mono-phenyl, mono-allyl, di-propyl, di-butyl, di-pentyl di-hexyl,di -benzyl, di-phenyl, di-allyl.
• the resulting ether or carbonate product, respectively can be either: a mono-alkyl, ether or dialkyl ether, or mono-alkyl, mono-allyl, mono-aryl carbonate, or dialkyl, diallyl, or diaryl carbonate.
• the present disclosure pertains to the ethers, acetates and alkyl-carbonates synthesized according the foregoing method.
• the mono-ether of the alkylene glycol compound is at least one of the following: mono-ether of ethylene glycol (EG), propylene glycol
• the mono-acetate of the alkylene glycol compound is at least one of the following: ethylene glycol, propylene glycol mono-acetate, or 2,3-butane-diol (BDO).
• the acetate of the alkylene glycol compound is at least one of the following:
• the mono- or dialkyl-carbonate product can contain at least one of the following: alkyl, allyl or aryl groups: a mono-butyl, mono-pentyl, mono-hexyl, mono-benzyl, mono-phenyl, mono-allyl, di-butyl, di-pentyl, dihexyl, di-benzyl, di-phenyl, di-allyl, or a mono- or di-alkyl group from C3-C20 carbon atoms.
• FIG. 2 A synthesis according to an embodiment of the present method is illustrated in Figure 2.
• the propylene glycol reacts with a dicarbonate under heat and in the presence of a nucleophile, such as potassium carbonate, to generate propylene glycol alkyl ethers.
• a nucleophile such as potassium carbonate
• ethers can further be processed to make propylene glycol alkyl ether acetates by treating with an acetyl-alcohol and acid.
• alkylation reactions depicted in Figures 3 and 4 show alternate embodiments using furanic diols, FDM and bHMTHFs, respectively.
• FDM reacts with dialkyl-carbonate to produce FDM alkyl ether, which is subsequently converted to FDM alkyl ether-acetate.
• An advantage of the present methods is that they can provide simple, clean and elegant processes for preparing ethers directly from an alkylene glycol, in particular a biologically-derived alkylene glycol.
• biologically-derived or bio-based refer to hydrocarbon molecules produced from renewable biological resources such as plants, cellulosic, or agricultural biomass or derivatives thereof, in contrast to so-called fossil-based or petroleum-based hydrocarbons.
• the clean process can help to simplify downstream separation and purification processes.
• the dialkyl ether analog when the etherification is conducted neat in dialkyl carbonate, the dialkyl ether analog is the only product observed.
• dialkylcarbonate i.e., a stoichiometric amount of alkylating agent
• monoether products are generated, although in relatively low yields (e.g., ⁇ 10%).
• Most of the propylene glycol or ethylene glycol remains unreacted.
• Optimization of the conditions can improve target yields. Improved yields of target monoalkyl ethers, for instance, can be achieved using about two or three equivalents of dialkylcarbonate and modifying other reaction parameters such as a lower temperature or longer reaction time.
• the method provides an environmentally benign approach for etherification of the glycols, according to a controlled reaction performed under relatively mild temperature and ambient pressure.
• the reaction is performed generally at a temperature between about 70°C and 150°C.
• the reaction is at a temperature in the range of about 70°C or 80°C to about 130°C or 140°C. More typically, the reaction temperature is in a range from about 80°C or 90°C to about 1 10°C or 120°C (In most reactions, the temperature is under about 125°C.
• These mild reaction conditions help to control and minimize the formation of byproduct compounds or other potential isomers and impurities.
• FIG 3 shows a schematic of a synthesis reaction according to an embodiment in which a FDM is reacted with dialkyl-carbonate to form a FDM mono-alkyl-ether. Subsequently, the ether is acetylated to generate the corresponding FDM alkyl-ether-acetate.
• Figure 4 depicts a similar two-step reaction with bHMTHFs (THF-diols), where bHMTHF is converted to the corresponding THF alkyl ethers and then acetylated to the THF alkyl ether-acetates.
• the furanic diol is at least one of the following: FDM, bHMTHF diestereomers, respectively; FDM-mono-acetate, bHMTHF-mono-acetate diestereomers, respectively.
• the ether product has at least one of the following alkyl groups: a mono-alkyl, mono-ethyl, mono-allyl.
• the present reactions are adaptable to make organo-carbonates, which are a class of reactive platforms with diverse utilities, particularly in trans-esterifications, alkylations, or arylations.
• Figures 5-7 represent three separate generic reactions for preparation of carbonates according to different embodiments, when the R-group of the dialkylcarbonate reagent is C3 or greater, allyl, benzyl, or aryl.
• R-group of the dialkylcarbonate reagent is C3 or greater, allyl, benzyl, or aryl.
• propylene glycol is converted to a corresponding diaklokycarbonate.
• FDM is converted to a furan carbonate
• bHMTHFs are converted to isomeric THF carbonates.
• Glycol acetates constitute materials that are useful in applications, such as solvents, precursors for additives, binders, plasticizers, lubricants and surfactants.
• a 500 mL round bottom flask equipped with dean stark apparatus was charged with 100 g of propylene glycol, 75 g of acetic acid and 5 g of a macroporous polymer catalyst (known commercially as AmberlystTM 70 from Dow Chemical, Inc.) for use in high-temperature heterogeneous catalysis.
• the reaction mixture is heated to 120°C and water was removed from the reaction mixture. The residue contained mostly propylene glycol mono-acetate.
• a 500 mL round bottom flask equipped with dean stark apparatus was charged with 100 g of propylene glycol, 115 g of ethyl acetate and 0.5 g of sodium methoxide.
• the reaction mixture was heated to 90°C and ethanol was removed from the reaction mixture.
• the residue contained mostly propylene glycol mono-acetate.
• a I L autoclave engineer reactor was charged with 200 g of propylene glycol, 150 mL of acetic acid and 2 drops of Cone. H2SO4. The reactor body was assembled and the reactor was heated to 130°C for 3 h. The reactor was cooled. The product consisted mostly of propylene glycol mono- acetate.
• a 10 mL single neck boiling flask equipped with a PTFE coated magnetic stir bar was charged with 100 mg of A (FDM, 0.780 mmol), 539 mg of potassium carbonate (3.902 mmol), and 5 mL of dimethyl carbonate (413 mmol).
• a reflux condenser was fitted to the flask, and while stirring, the heterogeneous mixture was heated to 90°C for 8 hours. After this time, the residual potassium carbonate was removed by filtration, and the filtrate concentrated under reduced pressure.
• Example 2 Synthesis of ((2S,5R)-5-(methoxymethyl)tetrahydrofuran-2-yl)methanol, ((2S,5S)-5- (methoxymethyl)tetrahydrofuran-2-yl)methanol, ((2R,5R)-5-(methoxymethyl)tetrahydrofuran-2- yl)methanol B; (2R,5S)-2,5-bis(methoxymethyl)tetrahydrofuran, (2S,5S)-2,5-bis(methoxy- methyl)tetrahydrofuran, C
• Example 2 Synthesis of ((2R,5S)-5-(hydroxymethyl)tetrahydrofuran-2-yl)methyl propyl carbonate, ((2S,5S)-5-(hydroxymethyl)tetrahydrofuran-2-yl)methyl propyl carbonate, ((2R,5R)-5- (hydroxymethyl)tetrahydrofuran-2-yl)methyl propyl carbonate B; dipropyl (((2R,5S)-tetrahydrofuran- 2,5-diyl)bis(methylene)) bis(carbonate), dipropyl (((2S,5S)-tetrahydrofuran-2,5-diyl)bis(methylene)) bis(carbonate) C
• a single neck, 5 mL round bottomed flask equipped with a PTFE coated magnetic stir bar was charged with 100 mg of A (0.751 mmol), 1.17 mL dipropylcarbonate (DPC, 7.51 mmol), and 522 ⁇ L ⁇ DIEA (3.00 mmol).
• the neck was stoppered with a rubber septum affixed to an argon inlet and the mixture heated to 120°C overnight under an argon blanket with vigorous stirring. After this time, excess DPC and DIEA were removed under high vacuum, and the tacky, yellow oil dissolved in a minimum amount of methylene chloride, and charged to a pre-fabricated silica gel column.

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• 2014
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