A fixed-bed multi-tubular reactor for producing an alkenyl acetate by a gas phase catalytic oxidation reaction of a lower olefin, acetic acid and oxygen including a plurality of reaction tubes, a thermometer protection tube inserted into at least one of the plurality of reaction tubes, a thermometer inserted into the thermometer protection tube, and a shield disposed above the reaction tube into which the thermometer protection tube is inserted and attached to the thermometer protection tube, wherein an effective projection region of the shield entirely covers the inlet opening of the reaction tube into which the thermometer protection tube is inserted.

A fixed-bed multi-tubular reactor for producing an alkenyl acetate by a gas phase catalytic oxidation reaction of a lower olefin, acetic acid and oxygen including a plurality of reaction tubes, a thermometer protection tube inserted into at least one of the plurality of reaction tubes, a thermometer inserted into the thermometer protection tube, and a shield disposed above the reaction tube into which the thermometer protection tube is inserted and attached to the thermometer protection tube, wherein an effective projection region of the shield entirely covers the inlet opening of the reaction tube into which the thermometer protection tube is inserted.

A fixed-bed multi-tubular reactor for producing an alkenyl acetate by a gas phase catalytic oxidation reaction of a lower olefin, acetic acid and oxygen including a plurality of reaction tubes, a thermometer protection tube inserted into at least one of the plurality of reaction tubes, a thermometer inserted into the thermometer protection tube, and a shield disposed above the reaction tube into which the thermometer protection tube is inserted and attached to the thermometer protection tube, wherein an effective projection region of the shield entirely covers the inlet opening of the reaction tube into which the thermometer protection tube is inserted.

A fixed-bed multi-tubular reactor for producing an alkenyl acetate by a gas phase catalytic oxidation reaction of a lower olefin, acetic acid and oxygen including a plurality of reaction tubes, a thermometer protection tube inserted into at least one of the plurality of reaction tubes, a thermometer inserted into the thermometer protection tube, and a shield disposed above the reaction tube into which the thermometer protection tube is inserted and attached to the thermometer protection tube, wherein an effective projection region of the shield entirely covers the inlet opening of the reaction tube into which the thermometer protection tube is inserted.

The present invention relates to a process for the preparation of aqueous solutions of [1-.sup.13C]-hyperpolarized carboxylate containing molecules of diagnostic interest that comprises parahydrogenating with molecular parahydrogen unsaturated alkenyl or alkynyl esters of the concerned .sup.13C-carboxylate molecules.

The present invention relates to a process for the preparation of aqueous solutions of [1-.sup.13C]-hyperpolarized carboxylate containing molecules of diagnostic interest that comprises parahydrogenating with molecular parahydrogen unsaturated alkenyl or alkynyl esters of the concerned .sup.13C-carboxylate molecules.

The present invention relates to a process for the preparation of aqueous solutions of [1-.sup.13C]-hyperpolarized carboxylate containing molecules of diagnostic interest that comprises parahydrogenating with molecular parahydrogen unsaturated alkenyl or alkynyl esters of the concerned .sup.13C-carboxylate molecules.

The present invention relates to a process for the preparation of aqueous solutions of [1-.sup.13C]-hyperpolarized carboxylate containing molecules of diagnostic interest that comprises parahydrogenating with molecular para-hydrogen unsaturated alkenyl or alkynyl esters of the concerned .sup.13C-carboxylate molecules.

The present invention relates to a process for the preparation of aqueous solutions of [1-.sup.13C]-hyperpolarized carboxylate containing molecules of diagnostic interest that comprises parahydrogenating with molecular para-hydrogen unsaturated alkenyl or alkynyl esters of the concerned .sup.13C-carboxylate molecules.

The present invention relates to a process for the preparation of aqueous solutions of [1-.sup.13C]-hyperpolarized carboxylate containing molecules of diagnostic interest that comprises parahydrogenating with molecular para-hydrogen unsaturated alkenyl or alkynyl esters of the concerned .sup.13C-carboxylate molecules.