Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2000-03-23
2001-08-28
Richter, Johann (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
Reexamination Certificate
active
06281394
ABSTRACT:
The invention relates to processes for preparing vicinal diols or polyols from olefins or formic esters of vicinal diols.
Vicinal diols can be prepared by reacting olefins with hydrogen peroxide and formic acid. This initially results in a mixture—depending on the ratios of the amounts of the starting materials—of vicinal diols and formic esters of the vicinal diols, it being possible for one or both of the hydroxyl groups to be esterified. In order to obtain the vicinal diols, the formic esters must be cleaved. A number of processes are known for this.
DE-A-23 29 084 describes a process for preparing vicinal diols and their formates wherein firstly olefins are reacted with formic acid and hydrogen peroxide, and the reaction product is reacted with catalytic amounts of alkali metal or alkaline earth metal alcoholates to cleave the esters.
DE-A-29 37 840 relates to a process for the hydroxylation of short-chain aliphatic mono- or diolefins. The mono- or diolefins are reacted with formic acid and hydrogen peroxide, and the reaction mixture is then neutralized with sodium hydroxide solution and extracted with ethyl acetate in order to obtain the required diols.
U.S. Pat. No. 4,479,021 relates to a continuous process for preparing 1,2-alkanediols. This entails reacting 1,2-olefins with formic acid and hydrogen peroxide, after which the resulting alkanediol monoformate is hydrolyzed in a multistage process. The hydrolysis is carried out by adding concentrated aqueous alkali solutions, after which the reaction product is extracted with an organic solvent.
GB-A-2 145 076 relates to a process for preparing 1,2-alkanediols. This entails reacting 1,2-olefins with hydrogen peroxide and formic acid, and hydrolyzing the resulting esters with 25% strength sodium hydroxide solution, after which the organic phase is distilled.
In the above processes, the hydrolysis or cleavage of the resulting formic esters is carried out with alkalis. The resulting diols are subsequently removed by extraction or distillation. On the one hand, the processes result in salts of formic acid which has to be removed and disposed of or worked up in an elaborate manner and, on the other hand, the removal of the vicinal diols from the reaction mixture is complicated.
It is an object of the present invention to provide processes for preparing vicinal diols or polyols in which no salts of formic acid are produced. It is additionally intended that the processes be simple to carry out and afford the required products in high yield.
We have found that this object is achieved by a process for preparing vicinal diols or polyols from an organic reaction mixture containing formic esters of vicinal diols or polyols, in which water is added to the reaction mixture, without addition of bases, and the formic esters are hydrolyzed in a subsequent thermal treatment, the aqueous formic acid is removed, and vicinal diols or polyols remain behind. The removal in this case is preferably effected by distillation.
The object is further achieved by a process for preparing vicinal diols or polyols from a reaction mixture containing formic esters of vicinal diols or polyols, in which methanol is added, in an amount which is at least stoichiometric relative to the formyl groups, to the reaction mixture, which is subsequently thermally treated with removal of methyl formate, methanol and water as azeotrope, and vicinal diols or polyols remaining behind.
The object is further achieved by a process for preparing vicinal diols or polyols by reacting olefins with hydrogen peroxide and formic acid to give a reaction mixture containing formic esters, where appropriate removing the aqueous phase and cleaving the formic esters, in which the cleavage is carried out by one of the above processes.
The object is additionally achieved by a process for preparing vicinal diols or polyols by reacting olefins which have at least 10 carbon atoms with hydrogen peroxide and formic acid to give a reaction mixture containing vicinal diols and formic esters, in which the reaction mixture is cooled, where appropriate after removal of the aqueous phase, whereupon the vicinal diols which have formed crystallize out, and the crystallized vicinal diols are removed mechanically.
It has been found according to the invention that in a process for preparing vicinal diols or polyols, it is possible for the cleavage of the resulting formic esters to be avoided or to be carried out by hydrolysis in the absence of bases. The processes according to the invention moreover lead in short reaction times to high conversions, high yields and pure products.
The processes according to the invention have the following advantages in particular:
quantitative conversion
short reaction times
products of high purity are obtained with high selectivity
no isolation of the epoxide intermediate necessary
no salt produced
no (heavy) metal catalysis
no organic solvents
complete recycling respectively of the formic acid or of the formic acid/water azeotrope or of the methyl formate
use of aqueous hydrogen peroxide as oxidizing agent
no materials to be disposed of apart from the water produced.
The reaction of vicinal diols with hydrogen peroxide and formic acid will be described first.
Olefins which can be employed in the processes according to the invention are all olefins which can be reacted with hydrogen peroxide and formic acid. The olefins preferably have from 4 to 30+, particularly preferably 6 to 24, in particular 10 to 18, carbon atoms. They may be linear or branched olefins. It is preferred to employ linear olefins.
The olefins may contain one or more carbon-carbon double bonds. They preferably contain one carbon-carbon double bond, which may be terminal or internal. They preferably contain one terminal double bond. The olefin is moreover preferably linear.
The olefins which are employed may be unsubstituted but may also have substituents such as hydroxyl groups and/or functionalities from carboxylic or sulfonic acids, esters, aldehydes, ketones, ethers, halides, nitriles, amides, imides, amines (quaternary or protonated). The olefins are preferably unsubstituted.
Examples of suitable olefins are 1-hexene, 1-dodecene, 1-tetradecene, C
20-24
-&agr;-olefin, C
12-14
-&agr;-olefin which consists in particular of about ⅔ 1-dodecene and ⅓ 1-tetradecene.
It is also possible according to the invention to employ mixtures of olefins and crude products derived from the industrial synthesis of olefins.
The formic acid is usually employed as aqueous solution. This is preferably a concentrated aqueous solution containing from 50 to 100% by weight formic acid. Particularly employed are pure formic acid or an azeotrope of formic acid and water containing about 77% by weight formic acid.
The concentration of the hydrogen peroxide employed may vary within wide limits. The hydrogen peroxide is preferably employed in a concentration of at least 30%, particularly preferably of at least 50%. In place of formic acid it is also possible to use, for example, trifluoroacetic acid or a similar acid.
The molar ratio of olefin to formic acid to hydrogen peroxide in the reaction is preferably 1:0.3-10:1-4, particularly preferably 1:0.5-5:1-2. Particularly good results are obtained with molar ratios of 1:0.5-3:1-2. Examples of preferred molar ratios are 1:1:1, 1:2:1, 1:0.5:1-2, 1:3.5:2, 1:2:2, 1:2:1.5.
The content of formyl esters in the resulting reaction mixture increases with the content of formic acid in the reaction.
The reaction is preferably carried out at from 40 to 100° C., particularly preferably 80 to 100° C. under atmospheric pressure. The reaction can be carried out under elevated pressure. The reaction usually takes from 1 to 5 hours, preferably 2 to 4 hours. The reaction can moreover be carried out continuously or batchwise. The reaction is preferably carried out by mixing the olefin to be reacted with the selected amount of formic acid and, after heating to the reaction temperature, continuously adding the hydrogen peroxide. The hydrogen peroxide is preferably added at a rate of 0.1-1
Bogenstatter Thomas
Oftring Alfred
Ott Christian
BASF - Aktiengesellschaft
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Price Elvis O.
Richter Johann
LandOfFree
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