Processes for producing dialdehyde monoacetals

Details Processes for producing dialdehyde monoacetals Processes for producing dialdehyde monoacetals

1999-10-15

2000-12-26

Owens, Amelia

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C07D32100

Patent

active

061662259

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

A first aspect of the present invention relates to a method of preparing dialdehyde monoacetals. More particularly, the present invention relates to a method consisting of two steps instead of a direct method which consists of directly producing a dialdehyde monoacetal from a dialdehyde and a diol. According to the method of the present invention, in a first step, dialdehyde bisacetal (which is an intermediate) is firstly obtained and in a second step, this dialdehyde bisacetal obtained is used to produce a dialdehyde monoacetal.
A second aspect of the present invention relates to a high production-yield method for preparing glutaraldehyde monoacetal (GADMA) from a specific pyran and a diol. In more detail, the second aspect of the present invention relates to a method of preparing GADMA in a high yield by using reactions between by-products of the reaction in addition to the reaction of a specific pyran with a specific diol.
A third aspect of the reaction relates to a method for improving the yield in the method of the second aspect of the invention by specifically determining conditions for the distillation of GADMA.
The compounds in the first aspect of the invention will be abbreviated as follows using the numbers of the General Formulae.
These compounds are also used in the second and third aspect and referred to the numbers and abbreviations of their General Formulae as in the first aspect of the invention.
Regarding the second and the third aspects of the present invention, the compounds used are abbreviated as follows according to the numbers of their General Formulae. bisacetal which is a glutaraldehyde whose terminal formyl groups are both converted in acetal groups): GADBA;
The acetal compounds formed from the alcohol corresponding to the Y of the above-mentioned YDP and glutaraldehydes are referred as Y acetals.


TECHNICAL BACKGROUND

In general, dialdehyde monoacetals have formyl groups which can be easily converted into an amino group, a hydroxyl group, a carboxyl group or an aminocarboxyl group; on the other hand, their acetal group is extremely stable in neutral or basic conditions but can be easily converted into formyl group under acidic conditions. Consequently, using such characteristics, the two terminal groups of the dialdehyde can be easily converted into two different groups and each kind of these compounds is very important since they are very useful as intermediates for synthesis particularly for synthesis of medical, pharmaceutical and agricultural compounds.
Among them, GADMA which is a typical compound of the above-mentioned dialdehyde monoacetal is particularly considered as important.
Heretofore, several methods have been proposed in the prior art as industrial methods of preparing a dialdehyde monoacetal. However, it is preferred that starting materials can be economically and readily obtained as industrial chemical products which are commercially supplied. Accordingly, it has been thought to be advantageous to directly prepare a dialdehyde monoacetal via the reaction of a dialdehyde with a diol.
An example of this direct method is shown by the following reaction formula in which GA which is used as a dialdehyde and EG used as a diol are used to produce GADMA. ##STR1##
According to this reaction scheme, it seems that GADMA is readily produced. However, practically, it is difficult to obtain GADMA in high yield. The reason is that the above-mentioned reaction is an equilibrium reaction and, moreover, there is a chemical equilibrium system between GADMA and the following GADBA which are by-products, at the same time. ##STR2##
Consequently, as far as the above-mentioned reaction method is used, there will be some trouble regarding the isolation of GADMA via distillation of a reaction mixture containing the five following components GA, GADMA, GADBA, EG and water. Moreover, during distillation, low-boiling point compounds such as water are usually removed from the system and consequently, there is an increase of GADBA. For this reason, the yield of the target GA

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