Process for production of an oxetane

Details Process for production of an oxetane Process for production of an oxetane

2001-08-21

2003-02-04

Trinh, Ba K. (Department: 1625)

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

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C549S511000

Reexamination Certificate

active

06515152

ABSTRACT:

The present invention refers to a novel, simple and inexpensive process for manufacture of an oxetane, which process provides technical as well as environmental advantages. The process includes subjecting an alcohol, having at least two hydroxyl groups, to a reaction with a carbamide compound in the presence of at least one catalyst.
Oxetanes as disclosed and produced by the process of the present invention are compounds having at least one four-membered ring of general formula (I)
Oxetanes have been prepared by a number of synthetic methods. The generally available methods include
ring closure of 1,3-diol derivatives by the intramolecular Williamson reaction,
decomposition of cyclic carbonate esters, and
photochemical reaction of aldehydes and ketones with olefines.
The intramolecular Williamson reaction consists in general of the reaction of 1,3-halohydrins or their acetates with alkali. In 1878 trimethylene oxide, oxetane, was prepared for the first time by treating 3-chloropropanol with potassium hydroxide. 1,3-halohydrins and acetates thereof have since been widely used in the preparation of oxetanes. The use of acetate esters of said halohydrins often improves the oxetane yield. Hydrogen sulphate esters and sulphate esters are reported as replacements for 1,3-halohydrins in the intramolecular Williamson reaction. Mono(arenesulphonate) esters of 1,3-diols have also been used, especially for preparation of bicyclic oxetanes. Spiro-oxetanes have been prepared by treating di(phenylsulphates) with alkali.
Cyclic carbonate esters of diols decompose to oxetanes and carbon dioxide. The decomposition is normally carried at 160-260° C. in the presence of a basic catalyst.
Photochemical reaction of aldehydes and ketones with olefines (the so called Paterno-Büichi reaction) comprises generally that an olefine and an aldehyde or ketone are irradiated in an inert atmosphere by a high-pressure mercury lamp.
Further methods for preparation of oxetanes are disclosed in the patent literature, including
British patent no. 787,406 disclosing a process for preparing oxetanes, which process comprises reacting a triol with a carbonic acid derivative of formula O═C(X)
2
wherein X is a halogen atom or an alkyloxy, cycloalkyloxy, aryloxy or tetrahydrofurfuryloxy radical. Compounds included in said formula are for instance phosgene, monoesters of chlorocarbonic acid and diesters of carbonic acid. The conversion proceeds in two stages and the reaction in respective step is dependent on employed carbonic acid derivative. The use of toxic and highly hazardous compounds such as phosgene renders the process a large number of disadvantages and drawbacks.
Japanese Unexamined Patent Publication HEI 10-7669 teaches a method for manufacturing an oxetane having a hydroxymethyl group. The method comprises causing a triol to react with an alkyl or alkylene carbonate yielding a cyclocarbonate compound which subsequently is decarboxylated in the presence of an alkaline catalyst The applicability of disclosed process is substantially limited by the fact that employed carbonates are too expensive for normal industrial use.
Oxetanes can, furthermore, be derived from other oxetanes by for instance electrolysis, oxidation over a silver catalyst, cyclisation by the Freund reaction or by substitution of halogen atoms.
Commonly used methods for preparation of oxetanes, the properties of prepared oxetanes as well as their polymerisation are thoroughly discussed in handbooks and encyclopaedias such as “
Encyclopedia of Polymer Science and Technology
”, chapter “
Oxetane Polymers
”, vol 9, 1968, pp 668-701, John Wiley & Sons Inc.
The present invention provides unexpectedly a novel, simple, inexpensive and reliable process for production of an oxetane, which process provides technical as well as environmental advantages. The process can be summarised by below simplified reaction scheme (I)
wherein R
1
is —NH
2
or —NR′R″, wherein R′ and R″ is for instance hydrogen or alkyl, and wherein R
2
and R
3
may be a group such as alkyl, aryl or hydroxyalkyl. The process comprises subjecting an alcohol having two or more hydroxyl groups, which alcohol most preferably has at least one 1,3diol grouping, to a reaction with a carbamide at a molar ratio employing 1-2 moles of said carbamide on 1-2 moles of said alcohol, in the presence of at least one catalyst promoting and/or initiating transcarbonylation and/or pyrolysis. Preferred embodiments of the process of the present invention employ 1-1.2 mole of said carbamide on 1-1.8 mole of said alcohol. The reaction yields a reaction mixture comprising said oxetane, which subsequently is recovered by means of for instance distillation and/or extraction. The reaction is suitably performed in an inert atmosphere, such as nitrogen and/or argon atmosphere, and/or at a pressure of 0.01-1 bar, such as 0.1-0.5 bar. The reaction temperature is in preferred embodiments 100-250° C., such as 110-150° C. and/or 170-240° C. A suitable amount of catalyst is normally found within the range of 0.01-10 mole%, such as 0.5-2 mole%, calculated on moles of said alcohol, said carbamide and said catalyst. The reaction can also optionally be carried out in the presence of one or more solvents, such as an ethylene glycol, a propylene glycol, a butylene glycol, a hexanol, a heptanol, an octanol and/or a dodecanol. Suitable amount of said solvent is for instance 0.05-2, such as 0.1-1 or 0.2-0.5, moles on 1 mole of carbamide and alcohol.
A typical procedure can be exemplified as follows:
Carbamide and alcohol are mixed in for instance a molar ratio of 2:1 to 1:2, such as a 1:1 to 1:1.8, and at least one catalyst is added in the range of 0.01 to 10 mole %, such as 0.5 to 2 mole %, based on total moles of reactants and catalyst. Optionally, combinations of two or more catalysts can be used. The pressure in the reaction vessel is reduced to 0.01-1 bar, such as 0.1-0.5 bar. Optionally, a stream of an inert gas, such as nitrogen or argon, is passed through the vessel. The inert gas may be used combined with or instead of the reduced pressure. The temperature is then raised to 110-150° C., whereby a transcarbonylation starts. The temperature is preferably kept at 120-140° C. for 1 to 12 hours, such as 2 to 5 hours, or until the transcarbonylation is completed. A pyrolysis occurs subsequent to said transcarbonylation. The pressure is preferably reduced to 0.05 to 0.15 bar, such as 0.07 to 0.1 bar, and the temperature is slowly raised to 170 to 240° C., such as 180 and 200° C. The oxetane formed is suitably for instance continuously distilled off from yielded reaction mixture.
The preferred carbamide employed in the process of the present invention is as disclosed previously a compound of general formula (II)
wherein both substituents R
1
are —NH
2
or wherein each substituent R
1
independently is —NR′R″, wherein R′ is hydrogen, linear or branched alkyl having for instance 1-12, such as 1-8, carbon atoms or is part of a bond between the nitrogen atoms in the two substituents R′ thus being part of a ring formation, and wherein R″ is hydrogen or linear or branched alkyl having for instance 1-12, such as 1-8, carbon atoms. Carbamide is thus understood as for instance urea, N-alkylurea and N,N-dialkylurea. The preferred carbamide is urea, whereby the two substituents R
1
are —NH
2
.
The alcohol reacted with said carbamide according to the process of the present invention is in preferred embodiments a compound of general formula (III)
wherein each R
2
and R
3
independently is alky, alkyloxy, alkyloxyalkyl, aryloxyalkyl, hydroxyalkyl, hydroxyalkyloxy, aryl or hydroxyaryl and wherein each R
4
independently is hydrogen or alkyl. Said alkyl is preferably linear or branched alkanyl or alkenyl having 1 to 24 such as 3-24, 1-12, 4-12 or 2-8, carbon atoms.
The alcohol is in the most preferred embodiments of the present invention selected from the group consisting of 2,2-dialkyl-1,3-propanediols, 2-alkyl-2-hydroxyalkyl-1,3-propanediols and 2,2-di(hydroxyalkyl)-1,3-prop

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