Fluoral is obtained by gas-phase fluorination of chloral in the presence of a catalyst and then reacted with trimethyl orthoformate, thereby readily forming 1,2,2,2-tetrafluoroethyl methyl ether as an intermediate for production of desflurane. 1,2,2,2-Tetrafluoroethyl difluoromethyl ether (desflurane) is produced with high yield from the thus-formed 1,2,2,2-tetrafluoroethyl methyl ether by chlorination and fluorination. This method enables efficient industrial-scale production of desflurane useful as an inhalation anesthetic

Fluoral is obtained by gas-phase fluorination of chloral in the presence of a catalyst and then reacted with trimethyl orthoformate, thereby readily forming 1,2,2,2-tetrafluoroethyl methyl ether as an intermediate for production of desflurane. 1,2,2,2-Tetrafluoroethyl difluoromethyl ether (desflurane) is produced with high yield from the thus-formed 1,2,2,2-tetrafluoroethyl methyl ether by chlorination and fluorination. This method enables efficient industrial-scale production of desflurane useful as an inhalation anesthetic

Disclosed is an industrial method for efficient production of an ,-difluoroaldehyde compound, which includes reaction of an ,-difluoroacetate with hydrogen gas (H.sub.2) in the presence of a ruthenium catalyst and a base. By the adoption of specific reaction conditions (catalyst, base, pressure etc.), it is possible to produce the target ,-difluoroaldehyde compound with a high conversion rate and high selectivity.

Disclosed is an industrial method for efficient production of an ,-difluoroaldehyde compound, which includes reaction of an ,-difluoroacetate with hydrogen gas (H.sub.2) in the presence of a ruthenium catalyst and a base. By the adoption of specific reaction conditions (catalyst, base, pressure etc.), it is possible to produce the target ,-difluoroaldehyde compound with a high conversion rate and high selectivity.

A method of combatting colour loss from a dyed material, the method comprising contacting the material with a composition comprising an alpha-substituted aldehyde.

Disclosed is an industrial method for efficient production of an ,-difluoroaldehyde compound, which includes reaction of an ,-difluoroacetate with hydrogen gas (H.sub.2) in the presence of a ruthenium catalyst and a base. By the adoption of specific reaction conditions (catalyst, base, pressure etc.), it is possible to produce the target ,-difluoroaldehyde compound with a high conversion rate and high selectivity.

Disclosed is an industrial method for efficient production of an ,-difluoroaldehyde compound, which includes reaction of an ,-difluoroacetate with hydrogen gas (H.sub.2) in the presence of a ruthenium catalyst and a base. By the adoption of specific reaction conditions (catalyst, base, pressure etc.), it is possible to produce the target ,-difluoroaldehyde compound with a high conversion rate and high selectivity.

Disclosed is a method for preserving an ,-difluoroacetaldehyde alkyl hemiacetal of the following formula in a gas-liquid state having gas and liquid phases in a closed container under an atmosphere of oxygen (O.sub.2) or inert gas, characterized by: controlling the oxygen concentration of the gas phase in the container to be 5000 ppm or lower; and then storing the ,-difluoroacetaldehyde alkyl hemiacetal in the container under light-shielding conditions

##STR00001##

where R.sup.1 represents an alkyl group or a substituted alkyl group.

It is possible by this method to suppress conversion of the ,-difluoroacetaldehyde alkyl hemiacetal to difluoroacetic acid over a long term.

A method for improving preservation stability of 2,2-difluoroacetaldehyde according to the present invention include at least: a first step of forming a 2,2-difluoroacetaldehyde-alcohol composite system in which a 2,2-difluoroacetaldehyde hemiacetal coexists with an excess alcohol, wherein the total molar amount of the alcohol is 1.15 to 4.00 times the total molar amount of 2,2-difluoroacetaldehyde; and a second step of storing, in a storage container, the 2,2-difluoroacetaldehyde-alcohol composite system formed in the first step. It is possible by this method to suppress the conversion of the 2,2-difluoroacetaldehyde hemiacetal to a dimer and maintain the original aldehyde activity of the target compound with less composition change over a long term.

A method for improving preservation stability of 2,2-difluoroacetaldehyde according to the present invention include at least: a first step of forming a 2,2-difluoroacetaldehyde-alcohol composite system in which a 2,2-difluoroacetaldehyde hemiacetal coexists with an excess alcohol, wherein the total molar amount of the alcohol is 1.15 to 4.00 times the total molar amount of 2,2-difluoroacetaldehyde; and a second step of storing, in a storage container, the 2,2-difluoroacetaldehyde-alcohol composite system formed in the first step. It is possible by this method to suppress the conversion of the 2,2-difluoroacetaldehyde hemiacetal to a dimer and maintain the original aldehyde activity of the target compound with less composition change over a long term.