4-formylamino-N-methylpiperidine derivatives, the use...

Details 4-formylamino-N-methylpiperidine derivatives, the use... 4-formylamino-N-methylpiperidine derivatives, the use...

2002-09-27

2004-05-18

Desai, Rita (Department: 1625)

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

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C546S190000, C546S191000

Reexamination Certificate

active

06737527

ABSTRACT:

The present invention relates to 4-formylamino-N-methylpiperidine derivatives of the formula (I)
where R
1
to R
5
, n and Y are as defined in the Description, to a process for preparing these piperidine derivatives, to the use of the piperidine derivatives of the invention, or prepared according to the invention, for stabilizing organic material, in particular for stabilizing plastics or coating materials, and also to the use of the piperidine derivatives of the invention, or prepared according to the invention, as light stabilizers or stabilizers for wood surfaces.
The invention further relates to stabilized organic material which comprises piperidine derivatives of the invention or prepared according to the invention.
2,2,6,6-Tetraalkylpiperidine derivatives are known light stabilizers for organic polymers. Their lack of compatibility with polyolefins and with other plastics, and also their incompatibility with acids or with materials which form acids when exposed to light and/or heat are frequently unsatisfactory, as are the duration of their protection action, the intrinsic color of the substances, and the thermal decomposition of the stabilizers during incorporation into polymers at elevated temperatures.
EP 0 316 582 describes piperidine derivatives in which these aspects of property profile have been improved, and which have the formula
The definitions of R
1
to R
5
, n and Y here are similar to those in the compounds of the formula I of the present invention.
R
6
embraces hydrogen and C
1
-C
22
-alkyl, besides a large number of other radicals. Line 14 of page 4 of EP 0 316 582 gives a particularly preferred definition of R
6
, other than methyl, acetyl, cyanomethyl and aminoethyl, as hydrogen. This is seen again in the compounds of Examples 1 to 48, where R
6
is without exception hydrogen. Only in the compounds of the final example (Example 49) does the nitrogen atom of the piperidine ring have an acetyl substituent.
Though the other aspects of the property profile of these stabilizers are good, their duration of stabilization is still frequently unsatisfactory.
It is an object of the present invention to provide stabilizers which give a further improvement in the duration of stabilization of organic material, and moreover have the above-mentioned advantageous properties of the known stabilizers, e.g. good compatibility with the materials to be stabilized, such as polyolefins or other plastics, a low level of intrinsic color, and stability during incorporation into the material to be stabilized.
We have found that this object is achieved, surprisingly, with the aid of the 4-formylamino-N-methylpiperidine derivatives of the formula (I)
where
R
1
, R
2
, R
3
and R
4
, independently of one another, are C
1
-C
4
-alkyl, or R
1
and R
2
, or R
3
and R
4
, together are tetramethylene or pentamethylene,
R
5
is hydrogen or C
1
-C
4
-alkyl, and
n is 1 or 2, with the proviso that
for n=1:
Y is hydrogen, C
1
-C
22
-alkyl, C
2
-C
22
-alkenyl, C
3
-Cl
2
-cycloalkyl, or bicycloalkyl, cyano-, hydroxyl- or C
1
-C
4
-alkoxycarbonyl-substituted C
1
-C
22
-alkyl, ethereal-oxygen-, nitrogen- or sulfur-interrupted, unsubstituted or hydroxyl-substituted C
4
-C
22
-alkyl, unsubstituted or C
1
-C
4
-alkyl-, fluorine-, chlorine-, C
1
-C
4
-alkoxy or di(C
1
-C
4
-alkyl)amino-substituted C
7
-C
2
2-phenyl- or diphenylalkyl, unsubstituted or C
1
-C
4
-alkyl- or C
1
-C
4
-alkoxycarbonyl-substituted phenyl, a radical of the formula
 where R
1
to R
5
, independently of one another, are as defined above,
or C
1
-C
22
-alkyl containing heterocyclic radicals, and
for n=2:
Y is C
1
-C
22
-alkylene, C
5
-C
22
-cycloalkylene, C
8
-C
14
-phenylalkylene, phenylene, or C
4
-C
30
-alkylene interrupted by ethereal oxygen, by nitrogen, by sulfur, or by five- or six-membered heterocycles.
The compounds of the invention have no intrinsic color, have good compatibility with a very wide variety of organic materials, in particular with organic polymers, have low vapor pressure and therefore low volatility, are resistant to thermal decomposition and to the action of acids, and their duration of stabilization is better than that of the prior art compounds.
Preferred compounds of this invention are those where R
1
to R
4
are methyl.
Other preferred compounds are those where R
5
is hydrogen.
If n is 1, radicals which may be used for Y, besides hydrogen, are:
i) C
1
-C
22
-alkyl, such as methyl, ethyl, n- or isopropyl, n-, sec- or isobutyl, n- or isopentyl, hexyl, octyl, decyl, dodecyl, octadecyl, pivalyl, 3,3-dimethylbut-2-yl, neopentyl, 4-methylpent-2-yl and 2-ethylhexyl;
ii) C
2
-C
22
-alkenyl, such as vinyl, allyl, butenyl, pentenyl and oleyl;
iii) C
3
-C
12
-cycloalkyl, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl, cycloheptyl, cyclooctyl, cyclododecyl and bicycloheptyl, of which cyclopentyl and cyclohexyl are preferred; iv) cyano-, hydroxyl- or C
1
-C
4
-alkoxycarbonyl-substituted C
1
-C
22
-alkyl, such as cyanomethyl, hydroxyethyl, hydroxypropyl, hydroxybutyl, methoxycarbonylethyl and ethoxycarbonylethyl;
v) ethereal-oxygen-, nitrogen- or sulfur-interrupted, unsubstituted or hydroxyl-substituted C
4
-C
22
-alkyl, such as —(CH
2
)
3
N(CH
3
)
2
, —(CH
2
)
3
N(C
2
H
5
)
2
, —(CH
2
)
3
—OCH
3
, —(CH
2
)
3
—O—CH(CH
3
)
2
, —(CH
2
)
2
O—(CH
2
)
2
-OH, —CH
2
—(CH
2
)
2
—CH
2
—N(CH
2
)
3
, —(CH
2
)
2
—N[CH(CH
3
)
2
]
2
, —(CH
2
)
2
—N(C
2
H
5
)
2
, —(CH
2
)
2
N(CH
3
)
2
, —(CH
2
)
2
—OCH
3
and —(CH
2
)
2
OCH
2
CH
3
;
vi) unsubstituted or C
1
-C
4
-alkyl-, fluorine-, chlorine-, C
1
-C
4
-alkoxy- or di(C
1
-C
4
-alkyl)amino-substituted C
7
-C
22
-phenyl- or diphenylalkyl, such as benzyl, methoxybenzyl, methylbenzyl, ethylbenzyl, isopropylbenzyl, trimethylbenzyl, fluorobenzyl, chlorobenzyl, methylenedioxybenzyl, phenylethyl, phenylpropyl and phenylbutyl, dimethylaminobenzyl, diphenylmethyl and 1,3-diphenylprop-2-yl;
vii) unsubstituted or C
1
-C
4
-alkyl- or C
1
-C
4
-alkoxycarbonyl-substituted phenyl, e.g. phenyl, tolyl and methoxy- and ethoxycarbonylphenyl;
viii) a radical of the formula
 where R
1
to R
5
are as defined above, but in particular R
1
to R
4
are methyl, and in particular R
5
is hydrogen;
ix) C
1
-C
22
-alkyl containing heterocyclic radicals, for example
If n is 2, examples of radicals Y which may be used are:
x) C
1
-C
22
-alkylene and C
5
-C
22
-cycloalkylene, e.g. —(CH
2
)
o
—CH
2
— where o is an integer from 1 to 21,
xi) C
8
-C
14
-phenylalkylene and phenylene, for example
 where q is 0, 1, 2, 3 or 4;
xii) C
4
-C
30
-alkylene interrupted by ethereal oxygen, by nitrogen, by sulfur or by five- or six-membered heterocycles, for example
 where r is an integer from 1 to 33,
 where s is 0, 1, 2, 3, 4, 5, 6 or 7.
Other preferred piperidine derivatives of the formula I are those where n is 2. The radicals Y are therefore bivalent bridges, examples of which have been indicated in the groups (x) to (xii) listed above.
Particularly preferred piperidine derivatives are those where Y is a bivalent C
12
-C
22
-alkylene bridge. In particular C
1
-Cl
2
-alkylene bridges may be used for Y.
The compounds of the invention which have the formula (I) may, as also described in EP 0 316 582, be prepared by reacting compounds of the formula (II)
with formic acid or with formic esters, preferred esters being the methyl and ethyl esters. This process may be carried out with or without addition of a catalyst. These are especially Lewis acids, among which particular mention may be made of orthotitanic esters, specifically titanium orthobutylate.
Another path to the methylated compounds of the invention is provided by the reaction of the piperidine derivatives of the formula I′
where R
1
to R
5
, n and Y are as defined for formula I, with methylating reagents, e.g. methyl halides, such as methyl chloride, bromide or iodide, or else dimethyl sulfate. These methylating reactions are familiar to the skilled worker and therefore require no further explanation.
A process for preparing pyridine derivatives of the formula I which

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