Mineral oils: processes and products – Chemical conversion of hydrocarbons – With prevention or removal of deleterious carbon...
Reexamination Certificate
1998-12-16
2001-03-13
Yildirim, Bekir L. (Department: 1764)
Mineral oils: processes and products
Chemical conversion of hydrocarbons
With prevention or removal of deleterious carbon...
C585S004000, C585S005000, C585S832000, C585S950000
Reexamination Certificate
active
06200460
ABSTRACT:
The present invention relates to substance mixtures which comprise vinyl-containing compounds, at least one nitroxyl compound and iron compound, if appropriate also nitro compounds, and if appropriate also other costabilizers, a process for the purification or distillation of compounds of this type without premature polymerization thereof taking place, and the use of mixtures which comprise nitroxyl compounds and iron compounds, and if appropriate nitro compounds and/or costabilizers, for inhibiting the premature polymerization of vinyl-containing compounds and for stabilizing organic materials against the damaging action of free radicals.
It is known that many unsaturated compounds on increasing the temperature are prone to polymerization proceeding, as a rule, under free radical conditions. For example, vinylaromatic compounds, such as styrene or &agr;-methylstyrene, must thus be stabilized by suitable compounds in order to prevent premature polymerization during purification by distillation of the crude products obtained on a large scale. Customarily, in this process these stabilizers or polymerization inhibitors are added to the crude products to be distilled before or during the purification step. Despite this measure, considerable amounts of polymers are still obtained. In isolated cases, specially also during operational breakdowns, complete polymerization of the monomers or monomer mixture present can take place during the purification or distillation. High costs result in this case due to the enormous purification outlay and the production loss.
In the Soviet Patent Specifications 1 027 150, 1 558 888 and 1 139 722 the stabilization of styrene by the use of nitroxyl or bisnitroxyl compounds is described.
4-Acylaminopiperidine N-oxyl derivatives are employed in the earlier German Patent Application, 19 510 184.7 for the stabilization of free radical-polymerizable monomers.
The earlier German Patent Application DE 19 609 312.0 describes compositions which comprise vinyl-containing monomers and at least one N-oxyl compound of a secondary amine, the latter possessing no hydrogen atoms on the N-bonded C atoms.
Mixtures of vinylaromatic compounds with sterically hindered nitroxyl compounds which are activated by traces of oxygen are mentioned in the Specification WO 96/16921.
The Japanese Specification Hei 1-165 534 discloses 1-piperidyloxy derivatives as polymerization inhibitors for styrene. U.S. Pat. No. 3,733,326 describes the inhibition of the polymerization of vinyl monomers by the use of free radical precursor compounds.
Mixtures of nitroxyl and nitro compounds for the stabilization of vinylaromatic compounds or vinyl-containing monomers during purification or distillation are described in U.S. Pat. No. 5,254,760 and the earlier German Patent Application 19 622 498.5.
The effectiveness of the stabilizers described in these specifications and the stability of the monomer mixtures containing additives are good, an improved retardation/action being achieved by the higher content of nitro compounds described in the earlier German Patent Application 19 622 498.5. Therefore, in the case of an interruption in the supply of monomers and stabilization additive to the column, a better delaying action as regards time is achieved by these stabilizers up to the commencement of large-scale polymerization reactions.
However, since in these large-scale processes even relatively small amounts of polymers add up to large amounts of undesired by-product, there is a permanent need for even more effective polymerization inhibitors. A reduction in the amount of nitro compounds is also desirable with a view to improved handling by the operating personnel, and a reduction in possible environmental pollution.
It is thus an object of the present invention to make available mixtures of vinyl-containing compounds which are stabilized even more effectively against premature polymerization during purification or distillation.
We have found that this object can be achieved by substance mixtures which contain
(A) vinyl-containing compounds,
(B) an active amount of a mixture inhibiting the premature polymerization of the vinyl-containing compounds, comprising
(i) at least one N-oxyl compound of a secondary amine which carries no hydrogen atoms on the &agr;-C atoms, and
(ii) at least one iron compound,
(C) if appropriate nitro compounds, and
(D) if appropriate costabilizers.
Substance mixtures are preferred which contain from 99.9999 to 95% by weight of the component (i) and from 1 ppm to 5% by weight of the component (ii), in each case based on the total mixture (B).
Substance mixtures are particularly preferred which contain from 99.999 to 97% by weight of the component (i) and from 10 ppm to 3% by weight of the component (ii), in each case based on the total mixture (B).
Preferred vinyl-containing compounds (A) are those of the formula (Ia)
where:
R
1
, R
2
, R
3
and R
4
independently of one another are each hydrogen, C
1
-C
6
-alkyl, C
2
-C
6
-alkenyl, unsubstituted or substituted aromatic or heteroaromatic radicals or halogen,
with the-condition that not more than two of these radicals at the same time are unsubstituted or substituted aromatic or heteroaromatic radicals, or R
1
and R
2
or R
3
and R
4
together form a saturated or unsaturated C
3
-, C
4
-, C
5
- or C
6
-alkylene bridge, in which up to two nonadjacent C atoms can be replaced by N, NH, N(C
1
-C
4
-alkyl), N(C
6
-C
10
-aryl) or oxygen.
The C
1
-C
6
-alkyl radicals in this case include the linear alkyl chains from methyl through ethyl up to hexyl but also the corresponding branched radicals. Possible C
2
-C
6
-alkenyl radicals are likewise ethenyl, propenyl etc. up to hexenyl and the groups branched in the saturated moiety. Aromatic or heteroaromatic and unsubstituted and substituted groups which may be mentioned, for example, are phenyl, pyridyl, alkylphenyl or -pyridyl, such as methylphenyl or -pyridyl or ethylphenyl or -pyridyl, alkenylphenyl or -pyridyl, such as vinylphenyl or vinylpyridyl, carboxyphenyl or -pyridyl, formylphenyl or -pyridyl, sulfophenyl or -pyridyl, hydroxyphenyl or -pyridyl, aminophenyl or -pyridyl, nitrophenyl or -pyridyl, but also naphthyl or naphthyl substituted by alkyl, alkenyl, carboxyl, formyl, sulfo, hydroxyl, amino or nitro groups. The halogen radical customarily used is fluorine or chlorine, occasionally also bromine.
If, for example, compounds each having an aromatic or heteroaromatic radical on the one hand and a C
1
-C
6
-alkyl on the other hand are taken into consideration, then, if the remaining two radicals from R
1
, R
2
, R
3
and R
4
are hydrogen, &agr;-methylstyrene (2-phenyl-1-propene), the two &bgr;-methylstyrene isomers (cis- and trans-1-phenyl-1-propene), &agr;-ethylstyrene (2-phenyl-1-butene), the two &bgr;-ethylstyrene isomers (cis- and trans-1-phenyl-1-butene) up to &agr;-hexylstyrene (2-phenyl-1-octene) or the two &bgr;-hexylstyrene isomers (cis- and trans-1-phenyl-1-octene) result as an example of monomers to be added.
Similarly, when using the pyridyl radical instead of the phenyl radical the compounds 2-pyridyl-1-propene, cis- and trans-1-pyridyl-1-propene, 2-pyridyl-1-butene, cis- and trans-1-pyridyl-1-butene up to 2-phenyl-1-octene and the two isomers cis-1-pyridyl-1-octene and trans-1-pyridyl-1-octene result. Also included here, of course, are the isomers which differ by the position of the pyridine N atoms relative to the bond linking the vinyl group to the pyridyl group. If the phenyl or pyridyl radical is substituted by the abovementioned groups, compounds such as &agr;-methylstyrenesulfonic acid (2-sulfophenyl-1-propene), &agr;-methylnitrostyrene (2-nitrophenyl-1-propene), &agr;-ethylstyrenesulfonic acid (2-sulfophenyl-1-butene), &agr;-ethylnitrostyrene (2-nitrophenyl-1-butene), the similar pyridyl compounds or the cis/trans-isomers of the corresponding &bgr;-substituted compounds result. Of course, also included here are the isomers which result due to the position of the substituent on the benzene ring relative to the phenyl-vinyl bond or, in the case of the subst
Kessel Knut
Merger Roland
Mitulla Konrad
Schroder Jurgen
Sutoris Heinz Friedrich
BASF - Aktiengesellschaft
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Yildirim Bekir L.
LandOfFree
Substance mixtures containing stabilizers and compounds... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Substance mixtures containing stabilizers and compounds..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Substance mixtures containing stabilizers and compounds... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2470760