Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2008-03-14
2008-12-02
Parsa, Jafar (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
Reexamination Certificate
active
07459587
ABSTRACT:
Crude menthol is dissolved in nitrile series solvent and then menthol is precipitated by cooling the solution to thereby obtain optically and chemically substantially pure menthol, the enantiomeric excess thereof being more than about 99% e.e. and the chemical purity being more than about 99%. Preferred examples of the nitrile series solvent include acetonitrile and propionitrile. The dissolution of crude menthol is carried out at a temperature below 42° C., which is the melting point of menthol. The cooling temperature in crystallization is preferably at a room temperature or a little lower temperature than the room temperature. After crystallization of menthol, additional purification process such as a distillation may be conducted, if necessary.
REFERENCES:
patent: 394181 (1888-12-01), Hindhaugh, Jr.
patent: 4-260401 (1992-09-01), None
patent: 9-217084 (1997-08-01), None
Hongo Hideyuki
Mizuno Yasuhiro
Nakayasu Hidetoshi
McDermott Will & Emery LLP
Parsa Jafar
Takasago International Corporation
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