Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
2000-05-03
2003-11-11
Killos, Paul J. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C562S538000, C562S512000
Reexamination Certificate
active
06646160
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the preparation of carboxylic acid salts, and more particularly, to a method for the preparation of amino carboxylic acid salts by the reaction of primary aminoalcohols with a hydroxide base in the presence of a catalyst.
2. Description of Related Art
Carboxylic acid salts are useful in various applications. The salts can be neutralized to the corresponding acid which is also useful in a number of applications, such as a raw material for pharmaceuticals, agricultural chemicals, pesticides and the like. Many of such carboxylic acids are available commercially in large quantities.
Copper catalysts are known to be effective for the conversion of primary alcohols to carboxylic acid salts (Chitwood 1945) and, particularly, alkanolamines to aminocarboxylic acids (Goto et al. 1988). The prior art maintains that both metallic copper and copper salts or oxides (Cu
+
, Cu
2+
, or both) are suitable catalysts to facilitate this conversion.
A journal article “Structure and Activity of Chromium-Promoted Raney Copper Catalyst for Carbon Monoxide Oxidation” by Laine et al.,
Applied Catalysis,
44 (1-2), pages 11-22, discloses that chromium-promoted Raney copper catalysts were prepared, and their activity for the oxidation of carbon monoxide was measured. The surface area of the Raney copper catalyst was directly related to the aluminum content in the precursor alloy and to a lesser extent to the presence of chromium. Bulk cuprous oxide and cupric oxide were detected by x-ray diffraction in the Raney copper catalyst. The presence of chromium inhibited the formation of cupric oxide but not of cuprous oxide. The activity decreased as chromium content increased.
U.S. Pat. No. 4,782,183 to Goto et al. describes a method for the manufacture of amino carboxylic acid salts which comprises contacting an aminoalcohol with an alkali metal hydroxide in the presence of a Raney copper catalyst, or a copper catalyst supported on zirconium oxide. The catalyst can also be an inorganic or organic salt of copper, or an oxidized surface of a metallic copper that is then reduced with hydrogen.
U.S. Pat. No. 4,810,426 to Fields et al. describes a process for the production of N-phosphonomethylglycine by oxidizing N-phosphonomethylethanolamine, or the cyclic internal ester thereof, with an excess of an aqueous alkali and a copper catalyst, and thereafter, heating at a temperature between 200° C. and 300° C. The catalyst is selected from cadmium, zinc, copper, palladium, platinum, and their respective oxides, hydroxides, and salts.
U.S. Pat. No. 5,220,054 to Urano et al. describes a method for the manufacture is of amino carboxylic acid by the oxidative dehydrogenation reaction in the presence of an alkali metal hydroxide, a copper containing catalyst, and water characterized by maintaining the nickel concentration below 40 ppm.
U.S. Pat. No. 5,292,936 to Franczyk describes an improved process to prepare an amino carboxylic acid salt. According to the process an aqueous solution of an aminoalcohol is contacted with an alkali metal hydroxide in the presence of an effective amount of a Raney copper catalyst that has from about 50 parts per million to about 10,000 parts per million of an element selected from the group consisting of chromium, titanium, niobium, tantalum, zirconium, vanadium, molybdenum, manganese, tungsten, cobalt, nickel and mixtures thereof.
Although satisfactory results are achieved by the processes of the prior art to convert an alcohol to a carboxylate using a copper catalyst, or even a Raney copper catalyst, it has now been found, in accordance with the teachings of the present invention, that the process of the present invention can convert an alcohol to an acid salt with greater conversion. This increase in yield and selectivity results in significant capital savings and operating costs when such reactions are practiced on a commercial scale.
SUMMARY OF THE INVENTION
The present invention provides a new and useful improvement in the process to manufacture a carboxylic acid salt, particularly an amino carboxylic acid salt, from a primary alcohol, particularly a primary aminoalcohol.
The process of manufacturing amino carboxylic acids salts comprises contacting an aqueous solution of a primary aminoalcohol with a strong hydroxide base selected from the group consisting of an alkali metal hydroxide, an alkaline earth metal hydroxide, an ammonium hydroxide compound including a tetraalkyl ammonium hydroxide, or the like, to form a reaction mixture, in the presence of an effective amount of a catalyst. The primary aminoalcohol and the strong hydroxide base react in the reaction mixture to form an amino carboxylic acid salt. The catalyst comprises one or more of elements selected is from the group consisting of copper, cobalt, nickel, and cadmium as well as optionally lesser amounts of chromium, titanium, niobium, tantalum, zirconium, vanadium, molybdenum, manganese, tungsten, cobalt, nickel, and mixtures thereof.
The reaction mixture contains less than about 3000 ppm, preferably less than about 500 ppm, more preferably less than about 100 ppm of oxidized copper either in soluble, complexed, colloidal, or particulate form during the reaction. The copper containing catalyst contains less than 50 ppm by weight, preferably less than 10 ppm by weight, more preferably less than 1 ppm by weight, of oxidized copper compared to the weight of active catalyst prior to starting the reaction. Examples of oxidized copper include cupric and cuprous ions, copper oxides, copper hydroxides, and the like. The presence of oxidized copper leads to poorer catalytic selectivity and activity.
The concentration of oxidizing agents in the reactants is minimized to prevent formation of oxidized copper from metallic copper catalyst. The concentration of oxidizing agents in the feedstocks and in the reaction mixture is preferably less than about 1000 ppm total, more preferably less than about 500 ppm total, even more preferably less than about 200 ppm total, and most preferably less than about 40 ppm.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a new and useful improvement in the process to manufacture a carboxylic acid salt from a primary alcohol. More particularly, the present invention provides a new and useful improvement in the process to manufacture an amino carboxylic acid salt from a primary aminoalcohol.
The primary alcohols which are useful as starting materials in the process of the present invention can be monohydric or polyhydric, and also aliphatic, cyclic or aromatic compounds, including polyether glycols, which react with a strong base to form a carboxylate. It is necessary that the alcohol and the resulting carboxylate are stable in the strongly caustic mixture, and that the alcohol is somewhat water soluble.
Suitable primary monohydric alcohols include aliphatic alcohols which can be branched, straight-chain, or cyclic, and aromatic alcohols such as benzyl alcohol. The alcohols can be substituted with various non-hindering groups, provided that these substituent groups do not react with the hydroxide base or the catalyst at the temperatures and pressures for the conversion of the alcohol to the acid. Suitable aliphatic alcohols include ethanol, propanol, butanol, pentanol, and the like.
Aminoalcohols represented by the formula
are also useful as starting materials in the present process where n is from 2 to about 20. When R
1
and R
2
are both hydrogen and n is 2, the aminoalcohol is monoethanolamine. When one of R
1
and R
2
is —CH
2
CH
2
OH or —CH
2
COOH, and the other R group is hydrogen and n is 2, the resulting product from the aminoalcohol is an iminodiacetate salt. When both R
1
and R
2
are —CH
2
CH
2
OH or —CH
2
COOH, the resulting product from the aminoalcohol is a nitrilotriacetate salt. Specific aminoalcohols include, for example, n-hydroxyethylglycine acid, monoethanolamine, diethanolamine, triethanolamine, N-methyethanolamine, N-ethylethanolamine, N-isopropylethanolamine, N-but
Franczyk, II Thaddeus S.
Moench, Jr. William L.
Finkelstein Ira D.
Howrey Simon Arnold & White , LLP
Killos Paul J.
Monsanto Technology LLC
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