DE1914009A1 - Process for removing formaldehyde - Google Patents

Description

description

"~ 'March 19

to the patent application

Dr. Bernhard J ο ο s , Zurich 191 ADDQ

. concerning '

, Process for removing formaldehyde

The present invention relates to a method for removing formaldehyde from products, in particular solutions and flowable dispersions, which have an undesirable formaldehyde content.

In various technical products, especially in solutions and dispersions for the most diverse Uses can be more or less minor

undesirable amounts of formaldehyde may be present, ', where this formaldehyde can come from the raw materials used in the manufacture of the products. Kick frequently however, there are also formaldehyde concentrations in such products

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by decomposition or degradation reactions, which one or several of their constituents are subject to when stored on.

It is known that formaldehyde and formaldehyde-releasing compounds lead to repeated exposure Irritation of the skin and mucous membranes and, as a result, too Irritations and possibly sensitization. The presence of formaldehyde, even in low concentrations,

is therefore in technical products and products of the day! ₍ pharmaceutical®

lent use, e.g. in solutions for cosmetic and /

Purposes, formaldehyde resin glues or plastic objects extremely undesirable. j A procedure for removing

Formaldehyde from solutions containing formaldehyde as an undesirable impurity, found, which is characterized in that the solutions with a simple hydride of a metal of the first to third main group of the periodic table, with a complex boron or aluminum hydride, with hydrazine or a one-sided substituted alkyl or aryl hydrazine, optionally with the addition of amino acids. ^ ₁

Are suitable for the purposes of the invention in particular those hydrides and hydrazines which, when added

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ORIGINAL INSPECTED

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to formaldehyde-containing solutions immediately with the formaldehyde react without being detrimental to other components of the concerned To act as a solution or to enter into undesired side reactions. Furthermore, no undesired items may arise from the implementation Resulting reaction products or the reaction products must not have any undesirable changes in the to be treated Substrate, such as discoloration or the like.

call forward. It has been found that the simple hydrides of metals belong to the first to third main groups of the periodic Systems, complex boron and aluminum hydrides, hydrazine and monosubstituted alkyl and aryl hydrazines meet these conditions largely meet.

Ala possible hydrides are, for example: sodium hydride, lithium hydride, potassium hydride, calcium hydride, also the complex hydrides potassium borohydride, sodium borohydride, lithium borohydride, calcium borohydride, potassium aluminum hydride, the use of which is preferred. Suitable hydrazines are, in addition to the unsubstituted hydrazine, monosubstituted ones N-alkylhydrazines and N-arylhydrazines. Preferred works one with hydrazine itself.

The treatment according to the invention can be expedient

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take place at room temperature, but higher temperatures may also be used. The in the inventive

The amount of hydride or hydrazine to be used in the process depends on the amount of formaldehyde present, which can easily be determined in preliminary tests using customary analytical methods. You can work with stoichiometric amounts, for example; occasionally it can be W ; ' also be advantageous to use an excess of hydride or

i ·. . ·· ■■■

[■ to use hydrazine.

Unwanted free formaldehyde occurs e.g. in solutions and dispersions of ^ -... ^ nylolized organic compounds in water, or organic solvents, such as in solutions of mono- and dimethylolated Urea and thioureas, and also in compounds with resins containing N-methylol groups, such as dimethyloltriazone resins, as well as phenol-formaldehyde resins and the like. In general one can use the above

RN-CH ₂ OH

assign bonds to the following formula:

R »in which R and R ^{f are the} same or different and water

ORIGINAL INSPECTED 909842/1756

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substance, a linear or cyclic alkyl or hydroxyalkyl group, represent an amine or N-heterocyclic group, which is bound to a methylol group on the nitrogen

may have, where in the above formula N and R interrupted by a carbonyl, thiocarbonyl or carbimine group and also R and R »in a ring via optionally substituted ones Alkylene groups bonded to two nitrogen atoms sclr. can.

■

Example 1; ". ■"·>"·'

j

7 g of commercially available dimethylolurea are dissolved in 100 ml of water. After standing for some time, this solution will contain 0.7 % free formaldehyde.

i. hyd found, Add to this solution while stirring

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inal

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0.8 g of hydrazine in 10% aqueous solution were added. In the resulting mixture, formaldehyde can only be determined analytically in fractions of a per mille will. -

Example 2

18 g of commercially available dimethylolthiourea are dissolved in 100 ml of water. After a while it will be left standing in this solution a content of 1.6 # free formaldehyde was found « posed. 2.8 g of hydrazine in 10 ^ aqueous solution and 2 g of glycocolla are added to this solution with stirring In the resulting mixture, formaldehyde can only be determined analytically in fractions of a per mille.

Example 3

20 g of commercially available dimethylolethylene thiourea are dissolved in 100 ml of water. After standing for some time, a content of 0.35 % free formaldehyde is found in this solution. 0.8 g of hydrazine and 0.15 g of p-aminobenzoic acid are added to this solution with stirring. In the resulting mixture, formaldehyde can only be determined analytically in fractions of a per mill.

Solutions of antigen N-methylolated compounds that are used in cosmetics can also be used in an analogous manner or the like use.

ORIGINAL INSPECTED

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All features and information disclosed in the registration documents are, insofar as they are individually or in Combination are new compared to the prior art, claimed as essential to the invention.

-Patent claims-

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Claims (2)

! 19H009 claims ^ 1. Process for removing formaldehyde from solutions containing formaldehyde as an undesirable contaminant contain, characterized in that the solutions with a simple hydride of a metal of the first to third Main group of the periodic system, with a complex boron or aluminum hydride, with hydrazine or one-sided substituted alkyl or aryl hydrazine, 'optionally with the addition of amino acids. v (fc £ 2. The method according to claim 1, characterized in that that glycocolla or p-aminobenzoic acid are added. Si / eta
3/12/69. 909842 / $ 175 original