Phosphonic acid catalyst in dehydrative cyclization of 5 and 6 carbon polyols with improved color and product accountability

Patent metadata

Field	Value
Publication number	US-2017015676-A1
Application number	US-201415302368-A
Country	US
Kind code	A1
Filing date	Nov 19, 2014
Priority date	Apr 10, 2014
Publication date	Jan 19, 2017
Grant date	—

Abstract

A process for preparing materials derived from sugar alcohols such that the dehydration products exhibit better accountability and improved color to water-clear or near water-white appearance is described. In particular, the process involves employing a reducing Brønsted acid (e.g., phosphonic acid) for the catalysis of sugar alcohols to their corresponding dehydrated-cyclized products.

First claim

We claim:

1 . A method for preparing a cyclic dehydration product from 5 or 6 carbon polyols comprising: reacting a 5 or 6 carbon polyol with a reducing Brønsted acid catalyst in a reaction mixture, at a temperature and for a time sufficient to convert said 5 or 6 carbon polyol to corresponding cyclic dehydration products in a product mixture, wherein at least 70% of the 5 or 6 carbon polyol is converted to the corresponding cyclic dehydration products.

2 . The method according to claim 1 , further comprising purifying said dehydration products by at least a means selected from the group consisting of chromatography, crystallization, and distillation.

3 . The method according to claim 1 , wherein said reducing Brønsted acid catalyst is phosphonic acid.

4 . The method according to claim 1 , wherein said product mixture has an opacity and color appearance that ranges from translucent, with a medium brown to light honey color, to transparent, clear or near water-white color after completion of said reaction time, without being subject to a purifying or decolorizing operation.

5 . The method according to claim 3 , wherein said product mixture exhibits a color appearance after completion of said reaction time that is lighter and more translucent relative to a product mixture prepared using sulfuric acid catalyst at a catalyst load of ≧0.1 mol %, instead of the phosphonic acid catalyst for the same time and temperature.

6 . The method according to claim 3 , wherein said product mixture exhibits reduced levels of color body formation or accumulation in said product mixture relative to a product mixture prepared using sulfuric acid catalyst at a catalyst load of ≧0.1 mol. %, instead of the phosphonic acid catalyst for the same time and temperature.

7 . The method according to claim 1 , wherein said 5 or 6 carbon polyol is selected from the group consisting of sorbitol, mannitol, iditol, xylitol, and 1,2,5,6-hexanetetrol.

8 . The method according to claim 3 , wherein said reaction mixture includes one or more other acid catalysts in addition to phosphonic acid.

9 . The method according to claim 1 , wherein said reducing Brønsted acid is present at a catalyst load of about 1 mol. % to about 20 mol. % relative to a concentration of said 5 or 6 carbon polyol.

10 . The method according to claim 3 , wherein said phosphonic acid is at a catalyst load of about 2 mol. % to about 15 mol. % relative to a concentration of said 5 or 6 carbon polyol.

11 . The method according to claim 1 , wherein said reaction temperature is in a range from about 100° C. up to about 160° C.

12 . The method according to claim 1 , wherein from at least 80% to substantially all of said 5 or 6 carbon polyol is converted to said corresponding intramolecular dehydration product.

13 . The method according to claim 1 , wherein the product mixture further includes poly-condensation products and the relative concentration of said poly-condensation products in said product mixture is less than 25% of total products.

14 . The method according to claim 1 , wherein a yield of one species of said corresponding dehydration products is at least 50%.

15 . The method according to claim 1 , wherein said 5 or 6 carbon polyol is selected from the group consisting of mannitol, sorbitol, iditol and xylitol and said corresponding cyclic dehydration products include at least one member selected from the group consisting of 1,4-sorbitan, 2,5-sorbitans), isosorbide, isomannide, isoiodide, and 1,4-anhydroxylitol.

16 . The method according to claim 1 , wherein said 5 or 6 carbon polyol is 1,2,5,6 hexanetetrol and the corresponding cyclic dehydration product is 2,5-bis-(hydroxymethyl)-tetrahydrofuran diol (THF diol) as a primary product.

17 . The method according to claim 1 , wherein said 5 or 6 carbon polyol is selected from the group consisting of sorbitol and mannitol, and the corresponding cyclic dehydration products include isosorbide or isomannide as primary product and at least one of 1,4-sorbitan or 2,5-sorbitans as a secondary product.

18 . The method according to claim 1 , wherein said the reaction time is up to about 3 hours.

19 . The method according to claim 1 , wherein said reaction is at an operating pressure of about 5 torr to about 100 torr.

20 . The method according to claim 21 , wherein said reaction is at an operating pressure of about 10 torr to about 30 torr.

Assignees

• Archer Daniels Midland Co

Inventors

• Stensrud Kenneth
• Hagberg Erik

Classifications

• C07D307/20

  Oxygen atoms · CPC title

• C07D307/12 Primary

  Radicals substituted by oxygen atoms · CPC title

• C07D493/04 Primary

  Ortho-condensed systems · CPC title

• A23L27/34

  Sugar alcohols · CPC title

• C07C31/26

  Hexahydroxylic alcohols · CPC title