Process for the preparation of 5-perfluoroalkyl substituted...

Details Process for the preparation of 5-perfluoroalkyl substituted... Process for the preparation of 5-perfluoroalkyl substituted...

2000-08-03

2002-03-05

Morris, Patricia L. (Department: 1625)

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

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C546S199000, C544S136000, C544S366000

Reexamination Certificate

active

06353113

ABSTRACT:

The instant invention pertains to a superior process for making 2H-benzotriazole UV absorbers which are substituted by a perfluoroalkyl group, i.e. trifluoromethyl, usually at the 5-position of the benzo ring.
BACKGROUND OF THE INVENTION
Japanese TOKU-KAI-Hei 3-57690 generically discloses compounds where the benzo ring of the benzotriazole may be substituted by a host of groups including hydrogen, alkyl, alkoxy, aryloxy, halogen, substituted amino, cyano, nitro, acyl and trihalomethyl. The only specific benzotriazole compounds mentioned are those where the benzo ring is unsubstituted or is substituted at the 5-position by a chloro group. There is no evidence that the Japanese inventors made any trihalomethyl substituted benzotriazole.
German Patent Application 116,230 describes inter alia the preparation of 5-trifluoromethyl-2-(2-hydroxy-5-methylphenyl)-2H-benzotriazolyl-1-oxide. The only synthesis conditions disclosed for the entire group of compounds prepared show the diazotization of the appropriate o-nitroaniline with aqueous sodium nitrite and hydrochloric acid. The German workers offer no synthetic details or more importantly no yield information for the preparation of 5-trifluoromethyl-2-(2-hydroxy-5-methylphenyl)-2H-benzotriazolyl- 1-oxide.
In British Patent Application 2,319,035 and United States Pat. No. 5,977,219, all benzotriazole compounds containing a trifluoromethyl moiety at the 5-position of the benzo ring are referenced to the synthetic procedure of Example 1. Issues to be considered with this synthetic procedure are (a) a 100% excess of the diazonium salt relative to phenol is used; (b) the monoazo prepared by this method is described as a paste (generally materials with the consistency of a paste are impure); the pure monoazo is a solid with a melting point of 101-105° C.; (c) the yield of benzotriazole based on the phenol is 11% and is only 5.5% based on the CF
3
-substituted o-nitroaniline; (d) the diazotization preparation in Example 1 uses concentrated hydrochloric acid; (e) a paper in the J. Org. Chemistry, 1985, (50) 3612 indicates that the reaction of 4-trifluoromethyl-2-nitro aniline with hydrochloric acid can lead to the formation of 4-trifluoromethyl-2-chloroaniline. Such a reaction could at least partly account for the low yields seen with the use of concentrated hydrochloric acid in the diazotization step.
OBJECT OF THE INVENTION
The object of the invention is to provide a facile and improved process for the preparation of 5-perfluoroalkyl substituted 2H-benzotriazole UV absorbers.
DETAILED DESCLOSURE
By contrast, the instant process describes an improved process for the preparation of 5-perfluoroalkyl (preferably trifluoromethyl) substituted 2H-benzotriazoles where in the diazotization step aqueous alkali metal (preferably sodium) nitrite and concentrated hydrochloric acid are replaced by aqueous alkali metal (preferably sodium) nitrite and concentrated sulfuric acid; and most preferably where aqueous alkali metal (sodium) nitrite and concentrated sulfuric acid are replaced with anhydrous nitrosylsulfuric acid with concentrated sulfuric acid as a diluent to allow operation at safe concentrations.
The instant invention more specifically pertains to a process for preparing a compound of formula I
wherein
G
1
is hydrogen or chloro,
G
2
is perfluoroalkyl of 1 to 12 carbon atoms,
E
1
is hydrogen, straight or branched chain alkyl of 1 to 24 carbon atoms, straight or branched chain alkenyl of 2 to 24 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by one to three alkyl of 1 to 4 carbon atoms; or E
1
is alkyl of 1 to 24 carbon atoms substituted by one or two hydroxy groups,
E
2
is straight or branched alkyl chain of 1 to 24 carbon atoms, straight or branched chain alkenyl of 2 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by one to three alkyl of 1 to 4 carbon atoms; or E
2
is said alkyl of 1 to 24 carbon atoms or said alkenyl of 2 to 18 carbon atoms substituted by one or more —OH, —OCOE
11
, —OE
4
, —NCO, —NHCOE
11
or —NE
7
E
8
, or mixtures thereof, where E
4
is straight or branched chain alkyl of 1 to 24 carbon atoms; alkenyl of 2 to 18 carbon atoms; or said alkyl or said alkenyl interrupted by one or more —O—, —NH—or —NE
4
— groups or mixtures thereof and which can be unsubstituted or substituted by one or more —OH, —OE
4
or —NH
2
groups or mixtures thereof; or E
2
is —(CH
2
)
m
—CO—E
5
;
E
5
is OE
6
or NE
7
E
8
, or
E
5
is —PO(OE
12
)
2
, —OSi(E
11
)
3
or —OCO—E
1
, or straight or branched chain C
1
-C
24
alkyl which can be interrupted by —O—, —S— or —NE
11
and which can be unsubstituted or substituted by —OH or —OCO—E
11
, C
5
-C
12
cycloalkyl which is unsubstituted or substituted by —OH, straight chain or branched C
2
-C
18
alkenyl which is unsubstituted or substituted by —OH, C
7
-C
15
aralkyl, —CH
2
—CHOH—E
13
or glycidyl,
E
6
is hydrogen, straight or branched chain C
1
-C
24
alkyl which is unsubstituted or substituted by one or more OH, OE
4
or NH
2
groups, or —OE
6
is —(OCH
2
CH
2
)
w
OH or —(OCH
2
CH
2
)
w
OE
21
where w is 1 to 12 and E
21
is alkyl of 1 to 12 carbon atoms,
E
7
and E
8
are independently hydrogen, alkyl of 1 to 18 carbon atoms, straight or branched chain alkenyl of 2 to 18 carbon atoms, straight or branched chain C
3
-C
18
alkyl which is interrupted by —O—, —S— or —NE
11
—, C
5
-C
12
cycloalkyl, C
6
-C
14
aryl or C
1
-C
3
hydroxylalkyl, or E
7
and E
8
together with the N atom are a pyrrolidine, piperidine, piperazine or morpholine ring,
E
5
is —X—(Z)
p
—Y—E
15
wherein
X is —O— or —N(E
16
)—,
Y is —O— or —N(E
17
)—,
Z is C
2
-C
12
-alkylene, C
4
-C
12
-alkylene interrupted by one to three nitrogen atoms, oxygen atoms or a mixture thereof, or is C
3
-C
12
-alkylene, butenylene, butynylene, cyclohexylene or phenylene, each substituted by a hydroxyl group,
m is zero, 1 or 2,
p is 1, or p is also zero when X and Y are —N(E
16
)— and —N(E
17
)—, respectively,
E
15
is a group —CO—C(E
18
)=C(H)E
19
or, when Y is —N(E
17
)—, forms together with E
17
a group —CO—CH═CH—CO—, wherein E
18
is hydrogen or methyl, and E
19
is hydrogen, methyl or —CO—X—E2
0
, wherein E
20
is hydrogen, C
1
-C
12
-alkyl or a group of the formula
 wherein the symbols E
1
, G
2
, X, Z, m and p have the meanings defined above, and E
16
and E
17
independently of one another are hydrogen, C
1
-C
12
-alkyl, C
3
-C
12
-alkyl interrupted by 1 to 3 oxygen atoms, or is cyclohexyl or C
7
-C
15
aralkyl, and E
16
together with E
17
in the case where Z is ethylene, also forms ethylene,
E
11
is hydrogen, straight or branched chain C
1
-C
18
alkyl, C
5
-C
12
cycloalkyl, straight or branched chain C
2
-C
18
alkenyl, C
6
-C
14
aryl or C
7
-C
15
aralkyl,
E
12
is straight or branched chain C
1
-C
18
alkyl, straight or branched chain C
3
-C
18
alkenyl, C
5
-C
10
cycloalkyl, C
6
-C
16
aryl or C
7
-C
15
aralkyl, and
E
13
is H, straight chain or branched C
1
-C
18
alkyl which is substituted by —PO(OE
12
)
2
, phenyl which is unsubstituted or substituted by OH, C
7
-C
15
aralkyl or —CH
2
OE
12
, which comprises
diazotizing a perfluoroalkyl substituted o-nitroaniline of formula II
 using concentrated sulfuric acid and an alkali metal nitrite (preferably sodium nitrite) or nitrosylsulfuric acid (most preferably nitrosylsulfuric acid) to form the corresponding
diazonium salt of formula III
which then couples with a phenol of formula IV
to form a monoazobenzene compound of formula V
reducing the monoazobenzene intermediate of formula V to the corresponding 2H-benzotriazole compound of formula I by conventional reduction means; and
with the proviso that when concentrated sulfuric acid and alkali metal nitrite are used, E
1
and E
2
are alkyl of 1 to 4 carbon atoms; or E
1
can also be hydrogen.
Preferably, the instant process involves the preparation of a compound of formula
which compris

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