Process for preparing 4-aminodiphenylamine intermediates

Details Process for preparing 4-aminodiphenylamine intermediates Process for preparing 4-aminodiphenylamine intermediates

2002-05-10

2003-06-24

Barts, Samuel (Department: 1621)

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

Organic compounds

Amino nitrogen containing

C564S421000, C564S422000, C564S423000, C564S398000, C564S397000, C564S408000, C564S433000, C564S434000

Reexamination Certificate

active

06583320

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for preparing 4-aminodiphenyl-amines intermediates.
2. Related Art
4-Aminodiphenylamines are widely used as intermediates in the manufacture of alkylated derivatives having utility as antiozonants and antioxidants, as stabilizers for monomers and polymers, and in various specialty applications. For example, reductive alkylation of 4-aminodiphenylamine (4-ADPA) with methylisobutyl ketone provides N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylene-diamine, which is a useful antiozonant for the protection of various rubber products.
4-Aminodiphenylamine derivatives can be prepared in various ways. An attractive synthesis is the reaction of an optionally substituted aniline with an optionally substituted nitrobenzene in the presence of a base, as disclosed, for example, in U.S. Pat. No. 5,608,111 (to Stern et al.) and U.S. Pat. No. 5,739,403 (to Reinartz et al.).
U.S. Pat. No. 5,608,111 describes a process for the preparation of an optionally substituted 4-ADPA wherein in a first step optionally substituted aniline and optionally substituted nitrobenzene are reacted (coupled) in the presence of a base. In working examples, aniline and nitrobenzene are reacted in the presence of tetramethylammonium hydroxide as the base, and water and aniline are azeotropically removed during the coupling reaction.
International publication WO 00/35853 discloses a method of preparation of intermediates of 4-aminodiphenylamine by the reaction of aniline with nitrobenzene in a liquid medium where the reaction system consists of a solution of salts of true zwitterions with hydroxides. A combination of potassium hydroxide and betaine hydrate is exemplified. The reaction may take place in the presence of free oxygen.
EP publication 566 783 describes a method of manufacture of 4-nitrodiphenylamine by the reaction of nitrobenzene with aniline in the medium of a polar aprotic solvent in a strongly alkaline reaction system. A phase transfer catalyst such as tetrabutylammonium hydrogen sulfate is employed. This reference requires that the reaction be carried out in an oxygen-free atmosphere in order to prevent undesirable side reactions caused by oxidation.
U.S. Pat. No. 5,117,063 and International publication WO 01/14312 disclose processes for preparing 4-nitrodiphenylamine and 4-nitrosodiphenhlamine, using an inorganic base with crown ether, a phase transfer catalyst.
U.S. Pat. No. 5,453,541 teaches that an external desiccant, such as anhydrous sodium sulfate, may be used to absorb excess water in an anaerobic process for producing one or more 4-ADPA intermediates in which substituted aniline derivatives and nitrobenzene are brought into reactive contact.
The objective of the present invention is to provide a superior method for producing one or more 4-ADPA intermediates by reacting aniline and nitrobenzene in the presence of an organic base and an inorganic salt or a metal organic salt.
SUMMARY OF THE INVENTION
In brief summary, the primary embodiment of the present invention is for a method of producing one or more 4-aminodiphenylamine intermediates comprising the steps of:
(a) bringing an aniline or aniline derivative and nitrobenzene into reactive contact; and
(b) reacting the aniline and nitrobenzene in a confined zone at a suitable time and temperature, in the presence of a mixture comprising an inorganic salt or metal organic salt, or mixtures thereof, having a cation that would be a suitable cation of a strong inorganic base, an oxidant and one or more of an organic base selected from the group of compounds defined by:
where R
1
, R
2
, R
3
are the same or different and selected from any straight chain or branched alkyl group containing from 1 to about 20 carbon atoms, e is a whole number integer of value 0, 1, 2 or 3, (R
4
)
e
is hydrogen for e=0, R
4
is R
1
R
2
R
3
N
+
for e=1, 2, or 3, X is an anion capable of abstracting a proton from the nitrogen of an aniline or aniline derivative, Y is alkyl, aryl , alkyl aryl or benzyl and substituted derivatives thereof, Z is a substituent selected from the group consisting of hydroxyl, halo, and other hetero atoms, where a=the valence of the anionic moiety and is a whole number integer of 1, 2, 3 or 4, b and c are whole number integers of value 1, 2, 3 or 4 and d is a whole number integer of value 0, 1, 2, 3 or 4, said mixture not including a reaction product of betaine and a strong inorganic base.
Other embodiments of the present invention encompass details about reaction mixtures and ratios of ingredients and particular inorganic salts or metal organic salts and organic bases, all of which are hereinafter disclosed in the following discussion of each of the facets of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed to a method, as described above, for making intermediates of 4-ADPA that has superior yield and selectivity for those intermediates. Such intermediates comprise 4-nitroso- and/or 4-nitrodiphenylamines (p-NDPA and 4-NDPA, respectively) and salts thereof. The intermediates may then be hydrogenated to produce 4-aminodiphenylamine.
An example of a substituted and multifunctional organic base that is consistent with the above formula I is (2S, 3S)-bis(trimethylammonio)-1,4-butanediol dihydroxide. Other effective organic bases fitting formula I, in addition to those shown in the following examples, can be derived from tetraalkylammonium phase transfer catalysts, wherein the anion is replaced by hydroxide or other suitable anion form, in the literature such as C. M. Starks and C. Liotta, Phase Transfer Catalysis, Principles and Techniques, Academic Press, 1978 and W. E. Keller, Fluka compendium, Vol. 1,2,3, Georg Thieme Verlag, New York, 1986, 1987, 1992.
In previous work a phase transfer catalyst was employed with a strong inorganic base, however the method of the present invention achieves equivalent results by starting with an organic base and an inorganic salt or a metal organic salt. The organic base is defined by the formula above. The examples in the previous work that illustrate the effect of variables should pertain in general to the present invention with the appropriate substitutions of organic base plus inorganic salt for the phase transfer catalyst plus inorganic base.
Organic bases known or believed to be particularly effective in the method of the invention include quaternaryammonium hydroxides selected from the group consisting of, but not limited to, tetramethylammonium hydroxide, tetrabutylammonium hydroxide, methyltributylammonium hydroxide, benzyltrimethylammonium hydroxide (Triton B), tricaprylmethylammonium hydroxide, cetyltrimethylammonium hydroxide and choline hydroxide, and equivalent quaternaryammonium alkoxides, acetates, carbonates, bicarbonates, cyanides, phenolics, phosphates, hydrogen phosphates, hypochlorites, borates, hydrogen borates, dihydrogen borates, sulfides, silicates, hydrogen silicates, dihydrogen silicates and trihydrogen silicates.
The term “strong inorganic base” as used with respect to the meaning of a cation of an inorganic salt or metal organic salt is intended to mean a base that is capable of abstracting a proton from the nitrogen of an aniline or aniline derivative, and may include any base having a pK
b
less that about 9.4, which is the pK
b
of aniline. Various aniline derivatives may have different pK
b
values, but a pK
b
of about 9:4 is employed as a general guide. The base will preferably have a pK
b
less than about 7.4.
The term “capable of abstracting a proton from the nitrogen of an aniline or aniline derivative” as applied to anion “X” of formula I, is intended to mean an anion also having a pK
b
value as discussed above with respect to the strong inorganic base.
Possible anions for “X” in formula I, in addition to hydroxide, include: alkoxide (pK
b
<1), acetate (pK
b
=9.25), carbonate (pK
b
=3.75), bicarbonate (pK
b
=7.6), cyanide (pK
b
=4.7), phenolic (pK
b
=4.1), phosphate (

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