Trimethylolpropane alkyl dicarbonate, method of making, and method of using

Abstract

Trimethylolpropane Alkyl Dicarbonate (C8O6H11R) having the structure of is disclosed, along with a method of producing the Trimethylolpropane Alkyl Dicarbonate and a methods for producing polycarbonates from the Trimethylolpropane Alkyl Dicarbonate.

Description

TRIMETHYLOLPROPANE ALKYL DICARBONATE, METHOD OF MAKING, AND METHOD OF USING CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to US App. No.63 / 666916 filed July 2, 2024, which is entitled “Trimethylolpropane Alkyl Dicarbonate, Method Of Making , And Method Of Using”, said application being incorporated herein by reference. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not Applicable. BACKGROUND

[0003] Disclosed is a new polymeric compound - trimethylolpropane alkyl dicarbonate (TMPD) - and a method of using TMPD to produce polycarbonates, and in particular, aliphatic polycarbonates.

[0004] Aliphatic polycarbonates (APCs) are an important type of polymer; they are widely used in the fields of solid electrolyte, biological medicine, and high performance plastics. Hydroxyl-terminated APCs are the most common type of APC and are often cured with isocyanates to form polycarbonate polyurethanes. APCs are typically produced by a reaction such as the following:Reaction 1

[0005] In this reaction, a dialkyl carbonate (e.g., dimethyl carbonate) is mixed with a diol (e.g., 1,6 hexanediol) in the presence (1-5%) of a transesterification catalyst, (such as a 1 molar solution of potassium hydroxide (KOH) or sodium hydroxide PCT Patent Application CAMR H453WO / 22263.0005 40098579.v1(NaOH) in methanol). The R’ in the diol can be any aliphatic alkyl group such as, but not limited to, hexamethylene, propylene, cyclohexane or butylene. The molar ratio of dialkyl carbonate to the diol determines how large (how high in molecular weight) the polycarbonate is going to be. For example, the dialkyl carbonate and the diol can be combined in a 3:4 molar ratio along with catalyst (e.g. 270 pounds (~122.5 kg) of dimethyl carbonate and 472 lbs (~214.1 kg) of 1,6 hexanediol can be mixed together with 15 pounds (~2.3 kg) of a 0.5 molar solution of potassium hydroxide in methanol) in a reactor having a fractionating column and a distillation head attached to the top thereof. The mixture (reactants + catalyst) is then heated while stirring to a point at which the dimethyl carbonate refluxes in the fractionating column but does not go over the distillation head. With reference to the just noted reactants, in this example, R is dimethyl carbonate and R’ is hexanediol. As the reaction begins to take place, methanol (i.e., HOR is methanol (HOCH3)) is produced, as shown in Reaction 2, below.

[0006] With reference to the above example, dimethyl carbonate has a boiling point of 90°C whereas methanol has a boiling point of 65°C. Thus, the process includes monitoring the temperature of the vapor coming over the top of the distillation head, and keeping the top of the column at or below 65°C. If the temperature at the top of the column gets much above 65°C, the dimethyl carbonate reactant will be lost over the distillation head. As methanol is is distilled over, the temperature of the reaction (in the reactor) increases, though it is kept at or below 180°C. If the reactor temperature exceeds 180°C, the dialkyl carbonate (for example, dimethyl carbonate or diethyl carbonate) can alkylate the hydroxyl of the diol, forming an ether, and producing carbon dioxide and alcohol as a byproduct. The reaction is allowed to continue until there is no more distillate coming over the top of the fractionating column. PCT Patent Application CAMR H453WO / 22263.0005 40098579.v1

[0007] While the process works successfully, it is very time intensive. To produce a large quantity of polycarbonate (as would be required for commercialization of a product), the reaction can take 96 hours. Because of the temperature constraints, the reaction must be constantly monitored. Thus, the method is very expensive from a labor standpoint.

[0008] It would be desirable to provide a new method for producing aliphatic polycarbonates which is not so time intensive. BRIEF SUMMARY

[0009] I have found a method of producing polycarbonates from a new compound - trimethylolpropane alkyl dicarbonate (TMPD) - which substantially reduces the time and cost required to produce the polycarbonate. This is a biomimetic process in which the making of one intermediate chemical is used to make a wide range of molecules. The TMPD can be made in very large volumes, to reduce the production cost, and can then be stored and later utilized to make smaller batches of specific polycarbonates. The overall process time for producing polycarbonates can be reduced from about 96 hours to about 32 hours, cutting the process time by about a third; about 26 of these hours are for making the TMPD and about 6 hours are for making the polycarbonate using the TMPD. But an important added benefit in cost savings is that TMPD can be made in very large batches and stored. Polymers can be made easily and quickly in smaller batches at or where the polymers will be needed. This reduces production as well as shipping costs, since the alcohols used for extending TMPD to make polycarbonate are generally available around the world.

[0010] The TMPD is made by refluxing dimethyl carbonate (DMC) or diethylcarbonate (DEC) with a triol containing hydroxyls in gamma position to each other (three carbons apart). In particular the triol can be 2-ethyl-2- (hydroxymethyl)propane-1,3-diol, (otherwise known as trimethylol propane or TMP). The reaction for production of TMPD using TMP is shown below: PCT Patent Application CAMR H453WO / 22263.0005 40098579.v1,in which R is methyl or ethyl and M is a metal such as potassium, calcium, or sodium. TMPD has a molecular weight of 218g / mol when R is methyl, and a molecular weight of 232 g / mol when R is ethyl.

[0011] This reaction takes about 26 hours and does not require fractional distillation. The solution is simply refluxed for about 24 hours. In this reaction, the side product HOR is methanol, which is distilled away until the reaction temperature reaches about 100°C, which usually requires about 2-4 hours, depending on the amount of reactant and the size of the reactor and column. The reaction temperature should not go above about 140°C, because, above about 140°C ring-opening polymerization of the cyclic carbonate will occur and the material will become too viscous to work with. If ring opening polymerization does occur, it can be reversed, and the presence of the small polymers which would result from the ring-opening polymerization does not hinder the effectiveness of this technology.

[0012] The polycarbonate is then produced from TMPD by adding a desired mono-alcohol (such as benzyl alcohol), a di-alcohol (such as 1,6 hexanediol), or a tri- alcohol (such as trimethylolpropane) to the TMPD and heating the solution until no more methanol is distilled or the solution temperature reaches 120-160°C, depending on the boiling point of the alcohol. The temperature should not go above 210°C, in order to avoid decomposition of the carbonate and evolving carbon dioxide. In this way a wide range of linear or branched aliphatic polycarbonates can be made. Advantageously, TMPD can be made in bulk, which means the cost is dramatically reduced, and stored for later use for making desired polycarbonates. This substantially reduces the time for making the polycarbonate, especially if the polycarbonate is produced from a pre-existing supply of TMPD. PCT Patent Application CAMR H453WO / 22263.0005 40098579.v1DETAILED DESCRIPTION

[0013] The following detailed description illustrates the claimed invention by way of example and not by way of limitation. This description will clearly enable one skilled in the art to make and use the claimed invention, and describes several embodiments, adaptations, variations, alternatives and uses of the claimed invention, including what I presently believe is the best mode of carrying out the claimed invention. Additionally, it is to be understood that the claimed invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. The claimed invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0014] I have found that by using a new compound - trimethylolpropane alkyl dicarbonate (TMPD) - as the carbonate and trimethylol propane as the alcohol for the production of polycarbonates, the process for producing polycarbonates can be reduced to as little as 30 hours - less than 1 / 3 the time required using the standard method as described above. And because the TMPD produced can be used as a raw material for making a wide range of polycarbonate polyols, costs are further reduced by the ability to produce TMPD in large volumes. The TMPD can then be shipped and stored in bulk at various manufacturing sites, which could be located around the world. Polycarbonate polyols can be made from TMPD quickly and in smaller batches using simple distillation equipment. TMPD has the structure shown below:(TMPD) SYTHNTHESIS OF TMPD

[0015] TMPD, which is a di-carbonate, is synthesized similarly as described above using trimethylol propane (TMP) as the polyol. Importantly, the polyol should, at a minimum, contain three hydroxyls gamma (three carbons) from each other. TMP PCT Patent Application CAMR H453WO / 22263.0005 40098579.v1satisfies this requirement. In such a polyol, two hydroxyls gamma to each other can be carbonated to form a strained six-membered ring which provides a highly reactive site for extention of the TMPD to make a wide range of polycarbonates. But the fact that there is another hydroxyl, gamma to the just-noted hydroxyls, means that when an alcohol or polyol reacts with the cyclic carbonate via a transesterification reaction, the hydroxyl produced can displace the alkyl carbonate and form another reactive cyclic carbonate. In this way polymerization occurs. The reaction of producing TMPD, using TMP, is shown below in Reaction 4.Wherein R is methyl or ethyl; and M is potassium, sodium, or calcium. Reaction 4

[0016] In an illustrative synthesis of TMPD, 1792 grams (~13.4 mol) of TMP is combined with 2224 grams (~24.7 mol) of dimethyl carbonate (10% less or 100% more dimethyl carbonate can be used) and 12 grams of a 1.0 Molar solution of potassium hydroxide in methanol. The mixture is stirred under a blanket of nitrogen and heated until the solution is boiling and dimethyl carbonate is refluxing. The mixture is refluxed with the temperature at the top of the condensing column being controlled to ensure that the methanol distillate does not come over the top of the column. To this end, the temperature is controlled so that the temperature at the top of the column is below the boiling point of methanol, or below 65°C. The reaction starts when the reactor is at about 90°C (the boiling point of dimethyl carbonate). However, the temperature in the reactor ultimately drops because the reaction mixture starts to contain more and more methanol. Because the reaction temperature drops, the reaction temperature will remain below 90°C, and thus, the reaction need not be monitored. The reaction is allowed to continue for about 24 hours. After 24 hours, the reactor is heated up sufficiently to cause the methanol to come over the top of the column (i.e., so that the PCT Patent Application CAMR H453WO / 22263.0005 40098579.v1temperature at the top of the column exceeds 65°C. This is done until the reaction mixture reaches a temperature of about 100°C. At this point, the reaction is stopped. PRODUCTION OF POLYCARBONATES USING TMPD

[0017] The polycarbonate is produced from the TMPD by mixing TMPD with a desired alcohol in a reactor having a distillation head and a distillate collection vessel. The alcohol can be a mono alcohol (such as benzyl alcohol), a diol (such as 1,6 hexanediol), a triol (such as TMP), or a polyol. The amount of alcohol used will depend on the alcohol that is used. Preferably, the molar ratio of hydroxyls to TMP is less than 2:1. The mixture is heated to a temperature at which the methanol distils over the top of the column. The heating continues until all methanol produced in the side reaction of the carbonate and alcohol (similar to Reaction 2, above) is distilled (i.e., there is no more methanol distillate) or the temperature in the reactor (i.e., the reaction temperature) reaches 160°C, whichever comes first. At that point, the reaction is stopped. This reaction can take about 4 hours. However, the actual time will depend upon the quantity of reactants and the size of the column and the size of the reactor. This general reaction is shown below:

[0018] Advantageously, TMPD can be made in bulk and stored for later use for making desired polycarbonates. This ability to produce TMPD in bulk and store for later use dramatically reduces the production costs of TMPD and of polycarbonates. Additionally, it substantially reduces the time required for making the polycarbonate, especially if the polycarbonate is produced from a pre-existing supply of TMPD. As can be appreciated, the polycarbonate can be produced in four hours, rather than in 96 hours, if stored (i.e., previously made) TMPD is used. PCT Patent Application CAMR H453WO / 22263.0005 40098579.v1Example 1: Synthesis Of a Branched Polycarbonate Polyol Using TMPD

[0019] Dendrimeric or Spherical polycarbonate polyols are formed via the following reaction: ,• R is an alkyl group such as methyl or ethyl; and • R’ is any aliphatic alkyl group that is larger than R, including but not limited to propyl, butyl, benzyl, cyclohexyl .

[0020] An exemplary procedure for producing dendrimeric (spherical) polyols / polycarbonates comprises mixing TMPD with n-butyl alcohol and TMP in a reactor having a distillation head (a fractionating column or condenser is not needed). Preferably, there are fewer than two moles of hydroxyls for every mol of TMPD. For example, 775 grams (~3.3 - ~3.5 mol) of TMPD can be mixed with 264 grams (~3.6 mol) of n-butyl alcohol and 160 grams (~1.2 mol) of TMP This results in a hydroxyl:TMPD molar ratio of about 4.6:3.5 - 4.6:3.3 (or about 1.3 – 1.4). The mixture is heated to 120°C until the methanol produced in the above-noted reaction is distilled off and the distillation head reaches 90°C.

[0021] A more branched polymer can be made by replacing some n-butanol with TMP. A less branched polymer can be made by replacing some TMP with n-butanol. Example 2: Synthesis Of Linear Polycarbonate Polyol Using TMPD

[0022] A linear polyol with hydroxyls along the polymer backbone are formed via the following reaction: PCT Patent Application CAMR H453WO / 22263.0005 40098579.v1,• R is an alkyl group, such as methyl or ethyl; and • R’ can be any aliphatic alkyl group such as, but not limited to, hexamethylene, propylene, cyclohexane or butylene.

[0023] An exemplary procedure for producing the linear polyol comprises mixing 819 grams (~3.5 - ~ 3.8 mol) TMPD with 472 grams (~4 mol) of 1,6 hexanediol. The mixture is then heated under agitation to react the TMPD with the diol to produce the linear polyol. Methanol is distilled over and should stop when the reaction mixture reaches 160°C.

[0024] A lower molecular weight polymer can be made by using up to 10% more 1,6 hexanediol. A higher molecular weight polymer can be made by using up to 10% less 1,6 hexanediol.

[0025] As various changes could be made in the above methods without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. PCT Patent Application CAMR H453WO / 22263.0005 40098579.v1

Claims

CLAIMS:

1. Trimethylolpropane Alkyl Dicarbonate (C8O6H11R) having the structure of .

2. Alkyl Dicarbonate of Claim 1 wherein R is methyl or ethyl.

3. A method of making the Trimethylolpropane Alkyl Dicarbonate (TMPD) of either Claim 1 or Claim 2 comprising: combining a polyol having a minimum of three hydroxyls gamma (3 carbons) from each other with an excess of a dialkyl carbonate and a metal hydroxide catalyst in a reaction vessel having a condensing column; maintaining the temperature of the reaction vessel such that the temperature at a top of the condensing column is less than the boiling point of methanol; after a predetermined period of time (such as about 24 hours), heating up the reaction vessel sufficiently to cause methanol produced in a side reaction to come over a top of the reaction vessel; and stopping the reaction when the temperature in the reaction vessel reaches about 100°C.

4. The method of Claim 3 wherein the dialkyl carbonate is dimethyl carbonate.

5. The method of Claim 3 wherein the dialkyl carbonate is diethyl carbonate 6. The method of any of Claims 3-5 wherein the polyol is trimethylolpropane.

7. The method of any of Claims 3-5 wherein the polyol is trimethylolethane. PCT Patent Application CAMR H453WO / 22263.0005 40098579.v18. A method of producing an aliphatic polycarbonate using the Trimethylolpropane Alkyl Dicarbonate (TMPD) of either Claim 1 or Claim 2 comprising: mixing the TMPD with an alcohol in a reactor having a distillation head and a distillate collection vessel; heating the mixture of TMPD and alcohol until substantially all methanol produced by the reaction of TMPD with the alcohol is distilled and when the temperature in the reactor reaches about 160°C.

9. The method of Claim 8 wherein the alcohol is a mono-alcohol (i.e., ROH).

10. The method of Claim 8 wherein the alcohol is a polyol.

11. The method of any of Claims 8-10 wherein the step of heating the reaction is carried out for about 4 hours.

12. A method of producing a branched polyol using the TMPD of either Claim 1 or Claim 2; the method comprising: mixing TMPD with a first alcohol (R’(OH)n) and a triol (R(OH)3) to form a mixture; heating the mixture to about 120°C to about 160°C until HOR produced during the reaction is distilled off; and stopping the reaction when there is no more HOR in the vapor.

13. The method of Claim 12 wherein the triol is trimethylol propane (TMP) or trimethylol ethane (TME).

14. The method of either Claim 12 or Claim 13 wherein the first alcohol is a monoalcohol (HOR’).

15. The method of either Claim 12 or Claim 13 wherein the first alcohol is a triol, such as TMP. PCT Patent Application CAMR H453WO / 22263.0005 40098579.v1

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