Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-12-01
2001-10-16
Barts, Samuel (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S835000, C568S375000
Reexamination Certificate
active
06303836
ABSTRACT:
The present application relates to an advantageous industrial process for preparing 2-cyclododecyl-1-propanol from cyclododecene and propionic acid or derivatives thereof.
2-Cyclododecyl-1-propanol (also called hydroxyambrane) is a scent of the musk class and is becoming increasingly important (cf. EP 278 384 B1). The current process for preparing it starts from cyclododecanone and alkyl 2-bromopropionates (cf., for example, Angew. Chem. 108 (1996), 1312-13 or EP 278 384). In this process, the unsaturated 2-cyclododecylpropionic ester is formed in a Reformatsky reaction with zinc. Zinc bromide is produced and has to be disposed of. The resulting ester is subsequently catalytically hydrogenated or, as disclosed in EP 278 384, reduced with lithium aluminum hydride. Compounds formed via organohalogen compounds generally still contain traces of halogen. Since hydrogen halide is formed therefrom on hydrogenation, severe corrosion of the reactor material and of the hydrogenation catalyst is to be expected on catalytic hydrogenation of the ester to the corresponding alcohol. Moreover, it is known that traces of halogen of as little as about 1 ppm interfere.
The process described above is very suitable for preparing small amounts of 2-cyclododecyl-1-propanol. However, this process is unsuitable for industrial preparation, i.e. for preparing 2-cyclododecyl-propanol [sic] on the scale of tonnes, for the following reasons:
1. The alkyl 2-bromopropionates used as starting compounds, and thus the alkyl alpha-bromo-zincpropionates [sic] obtainable therefrom, are rather costly.
2. The preparation of the cyclododecanone by hydrogenation of cyclododecatriene and subsequent oxidation of the resulting cyclododecane is rather complicated industrially and therefore also costly.
3. The formation of hydrogen halides, which has been described above, on hydrogenation leads to corrosion problems for the reactors and the hydrogenation catalysts, which entails the need to use extremely costly reactor materials and leads to short service lives of the hydrogenation catalysts.
4. The zinc bromide produced in the reaction leads to great waste-water problems and requires complicated workup or disposal measures.
5. The reduction with lithium aluminum hydride described in EP 278 384 is prohibitive for industrial synthesis.
It is an object of the present invention to develop a process for industrial preparation of 2-cyclododecyl-propanol [sic] which avoids the disadvantages of the prior art process. The novel process ought thus to start from materials which are as easily obtainable and therefore as cheap as possible and ought to result, in the minimum number of reaction steps which are easy to carry out industrially, and in good yields, in an olfactorily pleasing product without causing waste-water problems due to high salt production.
We have found that this object is achieved by preparing 2-cyclododecyl-1-propanol even on the industrial scale by reacting cyclododecene with an excess of propionic acid or a propionic acid derivative in the presence of catalytic amounts of a free-radical initiator, and hydrogenating the 2-cyclododecyl-propionic acid which is formed, or the corresponding 2-cyclododecylpropionic acid derivatives, catalytically with hydrogen on hydrogenation catalysts.
It was surprising that hydroxyambrane, which is in demand, can be prepared in an olfactorily satisfactory purity in this way in a synthesis which can easily be carried out industrially and comprises only two reaction stages starting from cyclododecene, which can easily be prepared by trimerization of butadiene and subsequent partial hydrogenation.
Although Synthesis (1970) No. 3, 99 -140, had disclosed that addition of carboxylic acids or carboxylic acid derivatives onto olefins is possible in the presence of free-radical initiators, the yields obtained according to loc.cit. on reaction of the cycloolefins cyclopentene and cyclohexene are only 17 and 10%, respectively, of theory, in contrast to good yields on reaction of numerous open-chain olefins, so that it was absolutely impossible to expect that it would be possible to obtain yields satisfactory for industrial preparation on reaction with cyclododecene.
Methoden der organischen Chemie (Houben-Weyl), Volume V/1b, 4th edition 1997, pages 1058-1063, has also disclosed the free-radical addition of carboxylic acids or carboxylic acid derivatives onto olefins. However, addition of propionic acid or its derivatives onto cyclododecene as olefin was not mentioned anywhere. Since relatively large amounts of unwanted byproducts are generally formed in reactions initiated by free-radical initiators, it was additionally not to be expected that hydroxyambrane can be prepared in olfactorily adequate purity by such a reaction.
The invention accordingly relates to a process for preparing 2-cyclododecyl-propanol [sic] which comprises
A. reacting cyclododecene with propionic acid or one of its derivatives in the presence of catalytic amounts of a free-radical initiator and
B. reacting the 2-cyclododecylpropionic acid which is formed, or the corresponding derivative, with hydrogen on suitable hydrogenation catalysts at from 100 to 300° C. and under from 20 to 350 bar.
The novel process is particularly advantageous when the propionic acid derivatives used are its esters with lower (C
1
-C
6
) alkanols.
The novel process is particularly advantageous when the free-radical initiators are hydrogen peroxide, perborates, perdisulfates, permonosulfates, peracids, hydroperoxides, dialkyl peroxides, peresters, diacyl peroxides, peroxydicarbonates, perketals or ketone peroxides, in particular di-tert-butyl peroxide which is readily available.
The second reaction step, the catalytic hydrogenation, takes place well when the hydrogenation catalyst used contains one or more elements of groups Ib, VIb, VIIb and VIlIb, and IIIa, IVa and Va, of the Periodic Table of the Elements, especially when the hydrogenation catalyst used contains at least one of the elements copper, cobalt or rhenium.
The cyclododecene used as starting compound can easily be prepared by trimerization of butadiene to cyclododecatriene (cf. Angew. Chem. 75 (1963) 10) and subsequent partial hydrogenation thereof. Complete hydrogenation and subsequent oxidation of the resulting cyclododecane to cyclododecanone as in the known preparation process is therefore unnecessary.
The free radicals necessary for addition of the carboxylic acid or its derivatives can be generated by generally known methods. Examples which may be mentioned are irradiation and decompositon of free-radical initiators such as peroxides. Decomposition of peroxides is preferred. Examples of peroxides which may be mentioned are hydrogen peroxide, perborates, perdisulfates, permonosulfates, peracids, hydroperoxides, dialkyl peroxides, peresters, diacyl peroxides, peroxydicarbonates, perketals and ketone peroxides. Decomposition of the free-radical initiators is advantageously induced thermally. The peroxy compounds are employed in catalytic amounts. Thus, in general, from 0.01 to 1, preferably 0.05 to 0.8, in particular 0.1 to 0.6, mole equivalents of peroxy compound are used according to the invention per mole of cyclic olefin. The temperature for the free-radical addition depends on the peroxy compound employed. Since each peroxy compound starts to decompose at a different temperature, the temperature range for the novel process is quite large. It is generally from 30 to 250° C. If, for example, di-tert-butyl peroxide is employed, the temperature is preferably 120-160° C.
The reaction is generally carried out under a pressure at which the reactants are in the liquid state, there being no upper limit on the pressure.
The molar ratio of propionic acid or its derivatives to cyclododecene is generally between 400 and 1, preferably between 150 and 1 and, in particular, between 100 and 1. The propionic acid or its derivative moreover advantageously serves as solvent.
Particularly suitable propionic acid derivatives for the novel reaction are its e
Ebel Klaus
Pinkos Rolf
Barts Samuel
BASF - Aktiengesellschaft
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Price Elvis O.
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