JPS5851952B2 - Pyridoxine purification method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for purifying pyridoxine.

More specifically, the present invention relates to a method for purifying pyridoxine, which comprises purifying pyridoxine colored due to coexistence with iron ions using an enediol compound.

Originally, pyridoxine is colored by trace amounts of iron ions that are inevitably introduced during the manufacturing process, such as from tap water, manufacturing raw materials, activated carbon, etc., and the crystals are colored in normal crystallization methods.

The phenomenon in which pyridoxine is colored by iron ions (more specifically, ferric ions) is generally caused by a color reaction between phenol and ferric ions (commonly known as the ferric chloride reaction, a qualitative test method). It is a sensitive reaction.

This coloration mechanism is explained in the literature [Analytical Chemistry]
Anal, Chem, ) 24.979 (1952
)), it is thought that this is because phenols substitute into the hydrated molecules of ferric ions, and the phenols, which have become more acidic under the influence of iron ions, lose protons and form complex salts. There is.

The reaction formula is shown below.

The present inventors conducted intensive studies to industrially advantageously produce colorless pyridoxine crystals that do not contain iron ions, and found that iron ions were mixed into the crystals when purified using an enediol compound. It has been found that iron ions can be effectively suppressed or that iron ions can be effectively removed from crystals mixed with iron ions.

As an enediol compound, the general formula (wherein X and Y are the same or different -COOH1-CH
O1-CH(OH)CH3, -CH(OH)CH20H, z is R is -CH2
Compounds represented by 0H1-CH2CH20H (representing alkyl which may be substituted with a hydroxyl group or hydrogen) can be used particularly inexpensively.

Specific examples of enediol compounds include 2-ketoquidylonic acid (enol form), D-erythroascorbic acid, reductic acid, L-ascorbic acid, [the former two compounds are each represented by X--COOH, Y=-CH in the above formula] (OH)CH
20H; Z--CO-OCH2H20H), and the like.

The pyridoxine subjected to the purification method of the present invention and the pyridoxine obtained by the method of the present invention may be a free base or a non-toxic salt.

Specific examples of such non-toxic salts include hydrochloride, sulfate, and oxalate.

In a preferred embodiment of the present invention, when pyridoxine or a salt thereof is crystallized from a colored solution of pyridoxine or a salt thereof containing ferric ions, an enediol compound is allowed to coexist in the solution.

The amount of the enediol compound to be used may be equimolar to iron ion, but it is usually used in an amount of 2 to 100 times.

The coloring caused by iron ions disappears when approximately the same molar amount is added, but
It is observed that the amount of iron ions mixed into the crystal tends to decrease as the amount added increases.

Furthermore, even if an enediol compound is added in large excess, it is generally not substantially detected in the crystals.

For example, in the case of L-ascorbic acid, D-erythroascorbic acid, etc., 0.1% (weight ratio) relative to pyridoxine.
Even if it is added, the detection limit is IPPM and it is undetectable compared to the product.

Another preferred embodiment of the present invention is to wash the crystals of pyridoxine or its salt colored by iron ions with a solution containing an enediol compound, or to wash the colored crystals using a solution containing an enediol compound. This is done by recrystallization.

The amount of the enediol compound used in these cases is also the same as above.

As mentioned above, the present invention is usually carried out in the presence of a liquid medium, and although the liquid cannot be generalized, it is preferably acidic to neutral.

Further, the enediol compound used in the present invention may also be a salt, and specific examples of such salts include alkali metal salts such as sodium salts and potassium salts, such as calcium salts and magnesium salts. Examples include alkaline earth metal salts.

As described above, it can be said that the present invention is an excellent industrial production method that makes it possible to obtain crystals of pyridoxine of desired quality extremely efficiently from colored pyridoxine wrapped around iron ions or from its solution.

Examples are given below.

Example 1 A considerable amount of L-ascorbic acid as an enediol compound is added to an aqueous solution 11 containing 11% of pyridoxine hydrochloride, 1.3% of common salt, and 5.3 PPM of iron ions.

20% as pyridoxine hydrochloride at a liquid temperature of 47°C or less.
Concentrate under reduced pressure to % concentration and heat at 0°C for 2 hours while stirring.
Cool until crystallization occurs.

Collect the crystals with a glass filter and add 50ml of pure water at 5℃.
After washing with 50 ml of ethanol, vacuum dry overnight.

Iron in the crystals is determined by the bathophenanthroline-iron chelate method.

The color tone of the crystals can be determined by dissolving 1 g of crystals in pure water to make 6 ml.
The absorbance is shown in a 30 mμ 1 crrL cell.

Example 2

Claims (1)

[Claims] 1. A method for purifying pyridoxine, which comprises purifying pyridoxine coexisting with iron ions using an enediol compound. 2. The invention according to claim 1, wherein the enediol compound is vitamin C.