US 6894199, Process for the production of xylitol

 

(2R,4S)-Pentane-1,2,3,4,5-pentol

Xylitol  used to denote sugar alcohols) is a sugar alcohol sweetener used as a sugar substitute. Xylitol has the formula (CHOH)3(CH2OH)2 and is an achiral isomer of pentane-1,2,3,4,5-pentol. Xylitol is roughly as sweet as sucrose with 33% fewer calories. Unlike other sweeteners, xylitol is actively beneficial for dental health, reducing caries to a third in regular use, and has been shown to reduce the incidence of ear infections.

Xylitol is found in the fibers of many fruits and vegetables, and can be extracted from various berries, oats, and mushrooms, as well as fibrous material such as corn husksand sugar cane bagasse,and birch.[5] However, industrial production starts from xylan (a hemicellulose) extracted from hardwoods or corncobs, which is hydrolyzed into xylose and catalytically hydrogenated into xylitol.

L-XYLOSE

 

Marida&MigenPatent No. U.S. 6,894,199

Process for the production of xylitol The present invention relates to the production of xylitol. In particular, processes utilising L-xylose as an intermediate for xylitol production are described. The present invention also relates to process for the preparation or L-xylose, as an intermediate, by-product or end-product to be used per se.


Assignee:  Danisco Sweeteners Oy, Espoo, Finland
 
This is the first of two patents covering xylitol 16 that is widely used in many foods and confectionary products. 16 occurs naturally in low concentrations in fruits but is normally produced by synthetic means from a variety of natural sources. This patent describes a method of preparing 16 from l-xylose 14 that is not a naturally occurring material since natural xylose exists in the d-form. The patent describes a number of methods of producing 14, and Scheme 3 shows two of these that start from 11. Two options are available, and the first converts 11 to12 by a decarboxylation reaction using alkaline H2O2. Reduction of 12 using Ru/C forms 16containing 1416 can be obtained from the mixture by using an acidic ion-exchange resin (IER) to remove 14 and other impurities. The alternative route from 11 to 16 is via initial reduction using Raney Ni to give 13. This is then decarboxylated with NaOCl to give 14 and reduction using Raney Ni gives 16.
 

Scheme 3

 Figure
The patent covers a substantial amount of work and gives details of the purification of 16 by crystallisation. There is also described a process for the production of l-xylulose 15 by a fermentation process, and 15 can be converted to 14 by alkaline isomerisation.
 

Advantages–The process allows the production of the important sweetener from synthetic reagents

Xylitol crystals

File:Xylitol crystals.jpg

Picture of Xylitol

XYLITOL 3D STR

DIMER

J. Mater. Chem., 2009,19, 5956-5963

DOI: 10.1039/B900890J

Related topicshttp://pubs.rsc.org/en/content/articlelanding/2009/jm/b900890j/unauth

MORE ABOUT XYLITOL

Xylitol is a five-carbon sugar alcohol that is used as a sugar substitute. Xylitol is a naturally occurring sweetener found in the fibers of many fruits and vegetables, including various berries, corn husks, oats, and mushrooms. It can be extracted from corn fiber, birch, raspberries, plums, and corn. Xylitol is roughly as sweet as sucrose but contains 40% less calories.

Xylitol was first derived from Birch trees in Finland in the 19th century and was first popularized in Europe as a safe sweetener for diabetics that would not impact insulin levels. In the late 20th century, xylitol in granular form began to be mass produced in the United States under the brand name “Ultimate Sweetener” using beet plants in California. Today, using corn sources, most world supplies reportedly come primarily from China

One teaspoon of xylitol contains 9.6 calories, as compared to one teaspoon of sugar, which has 15 calories. Xylitol also contains zero net effective carbohydrates, whereas sugar contains 4 grams per teaspoon. Unlike Stevia, xylitol has virtually no aftertaste, and is advertised as “safe for diabetics and individuals with hypoglycemia”. This is because carbohydrates like sugar alcohol have less impact on a person’s blood sugar than regular sugars. Virtually all chewing gum sold in Europe is sweetened with xylitol. Xylitol is a “toothfriendly” sugar substitute. In addition to not encouraging tooth decay (by replacing dietary sugars), xylitol may actively aid in repairing minor cavities caused by dental caries. Recent research confirms a plaque-reducing effect and suggests that the compound, having some chemical properties similar to sucrose, attracts and then “starves” harmful micro-organisms, allowing the mouth to remineralize damaged teeth with less interruption.

Formal Chemical Name (IUPAC)
(2R,3r,4S)-pentane-1,2,3,4,5-pentol

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