Organic compounds -- part of the class 532-570 series – Organic compounds – Sulfinic or sulfenic acids or salts thereof
Reexamination Certificate
2000-03-14
2002-03-05
Geist, Gary (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Sulfinic or sulfenic acids or salts thereof
C562S126000, C252S062200, C252S188230
Reexamination Certificate
active
06353131
ABSTRACT:
The present invention relates to compositions containing sulfinic derivatives. In particular it relates to such compositions as contain sulfinic derivatives having reductive properties and in which the sulfinic derivative is stabilized to degradation by the addition of stabilizing agents.
Sulfinic derivatives are derivatives of sulfinic acid of the general formula
R—S(O)—O
−
M
+
.
The substituent R denotes an organic radical, such as a substituted or unsubstituted alkyl or aryl radical, or an inorganic radical, such as a substituted or unsubstituted sulfino or sulfinato radical. The substituent M
+
stands for a cation such as a proton, a unipositively charged metal cation or the equivalent of a multipositively charged metal cation necessary to compensate the electric charges.
Sulfinic derivatives have reductive properties and are industrially important auxiliaries primarily in the textile and paper industries, for example for the reduction of dyes in vat dyeing or for bleaching wood-containing papers.
However, sulfinic derivatives are not generally stable in storage. It is therefore necessary to store them in a well-sealed container in a cool, dry place, but they still degrade during storage, a process which can, under unfavorable circumstances, lead to self-ignition of the stored goods; as a result, sulfinic derivatives may have to be classified as dangerous chemicals. Besides this, their degradation leads to a constant reduction of the content of sulfinic derivatives in the stored goods and causes an unpleasant odor of sulfur dioxide and/or hydrogen sulfide which, in dyeing processes for example, is transferred to the dyed fabrics and thus to the clothing manufactured therefrom. This odor can be masked by perfuming, but this requires extra processing and does not solve the basic problem or other problems associated with poor stability in storage, such as the continual drop in the value of the stored goods, since a diminishing content of sulfinic derivative in the composition means that more and more of the composition will be required to achieve the same end. Another drawback associated with this poor stability in storage is the resultant inclination of the product to become sticky, which impairs its handling properties, for example its flow characteristics when it is removed from bins or its conveyability in screw transporters. The stability in storage of the sodium salts of sulfinic acid mostly used commercially is poorer than that of zinc salts of sulfinic acid, which are seldom used and which are not suitable for every application on account of the toxicity of zinc ions to aquatic organisms.
Sulfinic derivatives are therefore traded and used usually in the form of compositions in which the sulfinic derivatives are stabilized to counteract degradation by the addition of stabilizing agents. Thus JP-A 1970/26,610 (Derwent Abstract No 61104R-E), for example, teaches the admixture of from 1 to 50 parts of anhydrous sodium hydrogensulfite to 100 parts of sodium dithionite. JP-A 51,110,497 (Derwent Abstract No 85930X/46) discloses stabilized dithionite compositions which contain alkali metal carbonate and alkali metal bicarbonate or alkali metal benzoate. DE-A 2,031,820 discloses the stabilization of solid sodium dithionite particles by the application of coatings of propoxylated cellulose or starch. U.S. Pat. No. 3,054,658 teaches the stabilization of sodium dithionite by admixture with a sodium or potassium salt of a C
1
-C
10
fatty acid or benzoic acid. DE-A 2,107,959 teaches the stabilization of sodium dithionite by admixture with calcined soda and sodium diethylenetriamine pentaacetate. U.S. Pat. No. 5,296,210 discloses the stabilization of sodium dithionite by means of oxidic hygroscopic compounds or mixtures of compounds having alkaline properties. Explicitly mentioned are CaO, BaO, CaSO
4
/Na
2
CO
3
, SiO
2
/Na
2
CO
3
, Al
2
O
3
/Na
2
CO
3
and CaO/BaO. However, these substances suffer from the drawback of being insoluble in conventional ready-made, particularly aqueous, solutions of sulfinic derivatives, which hampers handling and use thereof on an industrial scale. German patent application No. 19905395.2 (filing date Oct. 2, 1999) discloses compositions which contain at least one sulfinic derivative and magnesium sulphate. These compositions show substantially slower degradation of the sulfinic derivative and considerably improved olfactory properties but experience shows that in some applications they can give rise to undesirable or even troublesome turbidity or precipitation in the solutions commonly used therein.
It is thus an object of the invention to provide a further composition containing sulfinic derivatives in which the sulfinic derivatives are stabilized to degradation to a higher degree than in most known compositions and, in addition, the occurrence of turbidity or precipitation during use of this composition is minimized.
Accordingly, we have found a composition which contains at least one sulfinic derivative and potassium carbonate. The composition of the invention shows a distinct improvement in stability over known compositions, in particular less reduction of the content of sulfinic derivative and less generation of objectionable odors and reduces the occurrence of turbidity or precipitation in solutions containing this composition.
The composition of the invention is preferably a solid composition and more preferably a solid flowable composition, from which the commercial solutions of sulfinic derivative(s) are prepared, for example by dissolution in a solvent such as water.
The composition of the invention contains at least one sulfinic derivative, which can be any known sulfinic derivative.
Sulfinic derivatives conform to the general formula
R—S(O)—O
−
M
+
.
The substituent R denotes an organic radical, such as a substituted or unsubstituted alkyl or aryl radical, or an inorganic radical, such as a substituted or unsubstituted sulfino or sulfinato radical.
Suitable alkyls are straight-chain or branched C
1
-C
10
alkyl groups which may be substituted. Preference is given to the use of C
1
-C
4
alkyls such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl or tert-butyl and more preferably to the use of a methyl group. Substituents other than hydrogen substituents can be used in these radicals, for example halogens such as fluorine, chlorine, bromine or iodine, oxygen-containing substituents such as oxy, alkoxy and/or hydroxy radicals, and/or nitrogen-contain-ing substituents such as amino and/or imino radicals. Preferably hydroxy or amino and imino radicals are used. Particularly preferred is the use of a 1-hydroxyalkyl radical, in particular a 1-hydroxyethyl or 1-hydroxymethyl radical (R=CH
3
—CH(OH)— or HO—CH
2
—) or an amino/imino methyl radical (R=H
2
N—(HN)C—) or condensation products of the hydroxyalkyl radicals with ammonia (R=H
2
N—CHR′—, M
+−
O—(O) S—CHR′—NH—CHR′— or [M
+−
O—(O) S—CHR′]
2
N—CHR′—), where M
+
has the meaning defined below and R′ stands for hydrogen or alkyl, particularly methyl. If M
+
and R′ occur more than once in a compound they can denote different substituents.
Suitable aryls are aromatic radicals containing at least 6 carbon atoms, which may be substituted. Preference is given to the use of substituted or unsubstituted phenyl groups. Substituents other than hydrogen can be used in these radicals, for example halogens such as fluorine, chlorine, bromine or iodine, oxygen-containing substituents such as alkoxy and/or hydroxy radicals and/or nitrogen-containing substituents such as (alkyl)amino radicals.
Suitable inorganic radicals are all radicals which do not impair the stability of the sulfinic acid unit. Preference is given to the use of sulfur-containing radicals and more preferably to the use of a sulfino or sulfinato radical (R=X
+−
O—(O)S—).
The substituent M
+
of the sulfinic derivatives is a cation, for example a proton, a unipositiv
Beckmann Eberhard
Krüger Rudolf
BASF - Aktiengesellschaft
Geist Gary
Keil & Weinkauf
Reyes Hector M
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