Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Reexamination Certificate
2002-03-18
2002-11-26
Padmanabhan, Sreeni (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
C568S875000, C568S909500
Reexamination Certificate
active
06486353
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a process for producing optically active 3,7-dimethyl-6-octenol which contains from 2 to 10% by weight optically active 3,7-dimethyl-7-octenol and is useful as a material for perfumes, etc. The invention further relates to a process for producing a cis-3,7-dimethyl-2,6-octadienylamine compound (hereinafter referred to simply as “nerylamine compound”) containing from 2 to 10% by weight cis-3,7-dimethyl-2,7-octadienylamine compound (hereinafter referred to simply as “&agr;-nerylamine compound”), these amine compounds being intermediates for those optically active compounds.
The optically active 3,7-dimethyl-6-octenol provided by the invention, which contains from 2 to 10% by weight optically active 3,7-dimethyl-7-octenol, has an elegant rosy fragrance and is extremely useful for fragrance impartation to aromatic articles.
BACKGROUND OF THE INVENTION
3,7-Dimethyl-6-octenol (hereinafter referred to also as “citronellol”) has conventionally been known as a material for rosy perfumes, and the d-, l-, and dl-isomers have already come to be produced and practically used [Motoichi Indo, Gôsei Kôryô(Kagaku To Shôhin Chishiki), Kagaku Kogyo Nippo Sha, 1996]. Such perfume substances are not limited to alcohols These compounds, even when slightly different in structure, can generally have utterly different fragrances and differ also in properties, e.g., the ability to be retained and volatility. Consequently, for obtaining a new perfume, it is highly important to synthesize many compounds and investigate their fragrances.
Disclosed as processes for producing a nerylamine compound through the telomerization of isoprene with an amine compound are a method in which an n-butyllithium catalyst is used (JP-A-49-48610 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”)), a method in which a catalyst prepared from a secondary amine, a conjugated olefin, and lithium metal is used (JP-A-51-4109), a method in which a catalyst prepared from a secondary amine, a polynuclear aromatic compound and/or a polyphenyl compound, and lithium metal is used (JP-A-53-135912), and a method in which a catalyst prepared from a secondary amine, a conjugated diene compound and/or polycyclic aromatic compound as an unsaturated hydrocarbon, a lithium salt, and sodium metal and/or potassium metal is used (U.S. Pat. No. 4,186,148).
However, the method disclosed in JP-A-49-48610 has the following drawbacks. The method necessitates a reaction time as long as from 5.5 to 24 hours despite the use of an n-butyllithium catalyst and has low selectivity to nerylamine. Consequently, it is difficult to apply the method to an industrial process for continuously conducting the reaction and this application is costly.
The method disclosed in JP-A-51-4109 has attained a yield as high as about 85% using a different lithium catalyst. However, a reaction time of 18 hours is necessary for attaining the yield. This method also is difficult to practice industrially.
The method disclosed in JP-A-53-135912 has succeeded in obtaining nerylamine in a yield of 86.4% by using a different lithium catalyst to react an amine with isoprene in a proportion of 1:5 at 80° C. for 3 hours. However, since the isoprene amount is excessively large as compared with the amine amount, there have been problems concerning the recovery of isoprene and the yield of nerylamine.
The method disclosed in U.S. Pat. No. 4,186,148 has succeeded in obtaining nerylamine in a yield of 85% by reacting an amine with isoprene in a proportion of 1:5 first at 65° C. for 1 hour and then at 80° C. for 4 hours. However, since the isoprene amount is excessively large as compared with the amine amount, there have been problems concerning the recovery of isoprene and the yield of nerylamine. In addition, this method is unsuitable for continuous reaction because preparation of the lithium catalyst necessitates use of a dangerous metal such as sodium or potassium Furthermore, although JP-A-49-48610 discloses an N,N-dialkyl(3-methyl-2-butenyl)amine (formula 5), an N,N-dialkyl(2-methyl-2-butenyl)amine (formula 6), and an N,N-dialkyl(2-isopropenyl-5-methyl-4-hexenyl)amine (formula 7), which are yielded as by-products by the method disclosed therein there are no descriptions therein concerning the &agr;-nerylamine represented by formula 4 in the invention. No descriptions concerning by-products are given in the specification of the other references cited above.
In a conventional method for asymmetrically isomerizing a cis-dialkyloctadienylamine obtained, the amine is isomerized in tetrahydrofuran using a rhodium-BINAP catalyst and then hydrolyzed with sulfuric acid to obtain an aldehyde (see U.S. Pat. No. 4,604,474)
The present inventors made intensive investigations on methods for synthesizing optically active 3,7-dimethyl-6-octenol (citronellol), which is useful as a material for rosy perfumes. During these investigations, they have found that when the telomerization of an alkylamine with isoprene, which is known as a process for producing cis-3, 7-dimethyl-2,6-octadienylamine (a nerylamine compound) serving as an intermediate for citronellol, is conducted under strictly selected reaction conditions, then cis-3,7-dimethyl-2,7-octadienylamine (an &agr;-nerylamine compound) serving as an intermediate for optically active 3,7-dimethyl-7-octenol, which also is useful as a material for rosy perfumes, is yielded in a large amount.
The inventors have further found that asymmetrically isomerizing the mixture of nerylamine and &agr;-nerylamine in the same manner as in the reaction step of synthesis of citronellol from nerylamine, subsequently hydrolyzing the mixture, and reducing the resultant citronellal mixture gives a mixture comprising optically active 3,7-dimethyl-7-octenol and optically active 3,7-dimethyl-6-octenol (citronellol) and this mixture is more useful as a material for rosy perfumes than conventional ones. The invention has been completed based on this finding.
SUMMARY OF THE INVENTION
An object of the invention is to provide a process for stably producing optically active 3,7-dimethyl-6-octenol which contains from 2 to 10% by weight optically active 3,7-dimethyl-7-octenol and is extremely useful as a material for rosy perfumes. Another object of the invention is to provide a process for efficiently producing a cis-3,7-dimethyl-2,6-octadienylamine compound (nerylamine compound) containing from 2 to 10% by weight cis-3,7-dimethyl-2,7-octadienylamine compound (&agr;-nerylamine compound) , these amine compounds being useful as materials for those optically active compounds.
The invention, which makes it possible to stably produce the above-described optically active 3,7-dimethyl-6-octenol (citronellol) containing from 2 to 10% by weight optically active 3,7-dimethyl-7-octenol, includes the following.
(1) A process for producing optically active 3,7-dimethyl-6-octenol, a compound having an excellent fragrance represented by formula (1),
containing from 2 to 10% by weight optically active 3,7-dimethyl-7-octenol represented by formula (2):
which comprises subjecting a mixture of an alkylamine and isoprene in a molar ratio in the range of from 1:4 to 1:4.5 to telomerization at a reaction temperature of from 80 to 100° C. for from 2.5 to 3.5 hours in the presence of an alkyllithium catalyst and/or phenyllithium catalyst to thereby prepare a nerylamine compound represented by general formula (3):
wherein R
1
and R
2
each represents a hydrogen atom or an alkyl, aralkyl, or aryl group having 1 to 10 carbon atoms, containing from 2 to 10% by weight &agr;-nerylamine compound represented by general formula (4):
wherein R
1
and R
2
each represents a hydrogen atom or an alkyl, aralkyl, or aryl group having 1 to 10 carbon atoms, asymmetrically isomerizing the resultant reaction product mixture, subsequently hydrolyzing the mixture to obtain a citronellal mixture, and then reducing the citronellal mixture.
(2) A process for producing a nerylamine compound represented by general formula (
Hagiwara Toshimitsu
Hori Yoji
Okeda Yoshiki
Yamada Shin-ya
Padmanabhan Sreeni
Takasago International Corporation
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