Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-06-09
2001-07-03
Richter, Johann (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S863000, C568S852000
Reexamination Certificate
active
06255541
ABSTRACT:
This application is the national phase under 35 U.S.C. §371 of PCT International Application No. PCT/FI97/00835 which has an International filing date of Dec. 30, 1997 which designated the United States of America.
The invention relates to a process for the preparation of polyvalent alcohols. More precisely, the invention relates to the preparation of polyvalent alcohols from aldehydes prepared by the aldolisation reaction and a subsequent hydrogenation reaction of said aldehyde to alcohols.
PRIOR ART
Neopentyl glycol and other corresponding alcohols are important intermediates, for example, in the production of various synthetic resins, such as acrylic resins, polyester resins, polyurethane resins, alkyd resins and polycarbonate resins. These alcohols are also used in the preparation of plasticizers, synthetic lubricants, surfactants, etc.
Neopentyl glycol and other corresponding alcohols have conventionally been prepared by two processes. In one process, formaldehyde and aldehyde are allowed to react with a strongly alkaline catalyst, such as sodium hydroxide, potassium hydroxide or calcium hydroxide, to form alcohol, such as neopentyl glycol. However, this process has the disadvantage that large amounts of corresponding formate are formed as a byproduct. Thus the process is not suitable for a commercial process, unless an economically profitable use is simultaneously found for the formate.
In the other process, the aldolisation reaction of formaldehyde and aldehyde is carried out in the presence of an amine catalyst, in particular triethylamine. Neopentyl glycol is obtained, for example, by reacting formaldehyde and isobutyraldehyde in the presence of triethylamine, whereby hydroxypivaldehyde is formed as the main product. This can further be hydrogenated, whereby the desired neopentyl glycol is obtained as the end product.
Many types of catalysts have been proposed as the hydrogenation catalyst. U.S. Pat. No. 4,250,337 proposes as the catalyst copper chromite with barium as its promotor. In U.S. Pat. No. 4,855,515, the catalyst used is a mixture of copper oxide and copper chromite, with manganese oxide as the promoter. In EP patent 343475, a mixed catalyst made up of platinum, ruthenium and tungsten is used as the catalyst.
Copper chromite alone is used as the catalyst in, for example, EP publication 522368. According to this publication, the quantity of byproducts formed in the aldolisation can be decreased in the hydrogenation by carrying out the hydrogenation in a suitable alcohol solvent, whereby the purity of the final neopentyl glycol can be increased.
The above-mentioned processes have various deficiencies. When triethylamine is used as the catalyst, the triethylamine is in a dissolved state in the reaction mixture and thus also present in the hydrogenation step, possibly catalyzing detrimental side reactions, thus reducing the yield of the desired alcohol. Triethylamine is a also a catalytic poison for many hydrogenation catalysts, which decreases the number of suitable catalysts that can be used. Further, triethylamine decomposes partly in the hydrogenation step increasing the catalyst consumption in the process. In order to minimize the catalyst consumption triethylamine must be separated after the hydrogenation by distillation from the reaction mixture obtained and be recycled to the hydrogenation and/or aldolisation reaction, which means one additional step in a continuous process.
Thus it would be beneficial if a catalyst of another type, which is not in a liquid form and will thus not end up in the reaction mixture going to hydrogenation, could be found to replace triethylamine, which is at present the most commonly used aldolisation catalyst. The investment costs of the entire process could thus be reduced, since a separate step for the separation of triethylamine from the hydrogenation product would not be necessary. Furthermore, many types of catalysts could be used in the hydrogenation without the catalyst poisoning caused by triethylamine and the consequent reduction of the conversion and/or the formation of byproducts.
The idea to use ion exchange resins as a catalyst in the aldolisation reaction is an old invention. U.S. Pat. No. 2,818,443 discloses a reaction of formaldehyde and an aliphatic aldehyde; containing at least two carbon atoms, in the presence of an anion exchange resin catalyst to form hydroxyaldehyde, which is further hydrogenated to the corresponding alcohol. In this patent it is noted that especially suitable anion exchange resins are resins containing quaternary ammonium groups, such as resins obtained by reacting tertiary amine with a copolymer of chloromethylated styrene and divinyl benzene. These resins are strong base anion exchange resins. It is also possible to use as the aldolisation catalyst a weak base anion exchange resin obtained by reacting dimethylamine with a copolymer of chloromethylated styrene and divinyl benzene.
According to this patent, the separation of unreacted formaldehyde from the reaction mixture before the hydrogenation is recommended. The separation is carried out by distillation under overpressure or by steam stripping under atmospheric pressure. The hydrogenation catalyst used according to this publication is Raney nickel.
DE patent 26 53 096 proposes the use of cation exchange resins as a catalyst for the aldolisation reaction. The aldolisation reaction can be performed in a suitable organic solvent, such as aliphatic alcohols. After the reaction, the cation exchange resin is removed by filtration, and any unreacted aldehyde is separated by distillation.
Recommended hydrogenation catalysts according to the patent are nickel- or cobalt-containing hydrogenation catalysts to which chromium, aluminum, magnesium, barium, zinc, manganese, thorium and/or copper has been added.
SUMMARY OF THE INVENTION
According to the present invention, it has been observed that by using weak base anion exchange resins as an aldolisation catalyst and by performing the hydrogenation of the aldolisation product in the presence of a solvent and a hydrogenation catalyst, many advantages are gained which are lacking in prior known processes.
The aldolisation reaction can be carried out with a good yield and without notable side reactions, especially the formation of esters. The selectivity of the process with respect to the desired alcohol increases. The aldolisation product can be fed directly to the hydrogenation step without any separation steps. No aldolisation catalyst, such as triethylamine, is present in the hydrogenation reaction, and thus its separation and recycling to the aldolisation step of the process is not necessary. Furthermore, it is possible in the hydrogenation step to use many kinds of catalysts without a triethylamine-catalyzed formation of byproducts and product purification steps related thereto. The hydrogenation can be carried out in milder conditions, because the use of solvent decreases considerably the temperature required enables reasonable low temperatures to be used in the hydrogenation step. Even temperatures below the melting point of the intermediate hydroxyaldehyde are possible. For example, hydroxypivaldehyde tends to decompose already at 130° C. Also harmful side reactions decrease as a result of lower hydrogenation temperature. The useful age of the hydrogenation catalyst is lengthened if the reaction mixture fed to hydrogenation does not contain triethylamine. Furthermore, in the process according to the invention the regeneration of the aldolisation catalyst is easy.
To achieve these advantages, this invention relates to a process for the preparation of polyvalent alcohols by hydrogenation of an aldehyde, in which process said aldehyde is obtained by aldolisation reaction of an aldehyde containing an &agr; hydrogen atom and having the formula R
1
CHO, or the mixture of said aldehyde with a second different aldehyde having the formula R
2
CHO, wherein R
1
is selected from alkyl having 1-12 carbon atoms, cycloalkyl, aryl and aralkyl having 1-14 carbon atoms, and R
2
is selected from H, alkyl
Haakana Rami
Hietala Jukka
Lahtinen Leila
Lindfors Lars Peter
Nousiainen Hannu
Birch & Stewart Kolasch & Birch, LLP
Neste Chemical Oy
Price Elvis O.
Richter Johann
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