A process for separating or removing permanganate reducing compounds (PRC's) from a first mixture containing at least one PRC, methyl iodide, and water comprises the steps of: feeding the first mixture to a feed port of a distillation column, and distilling and separating the first mixture into an upper stream and a lower stream, wherein the distillation of the first mixture forms a second mixture at an upper position than the feed port, and the process further comprises the steps of: withdrawing the second mixture as the upper stream, and withdrawing the lower stream from a lower position than the feed port.

The invention relates to a process for the continuous production of acrylic acid, in the absence of organic solvent and in the absence of chemical treatment of the aldehydes, and without employing a dividing-wall column, from a gaseous reaction mixture comprising acrylic acid obtained by gas-phase oxidation of a precursor of acrylic acid.

The invention relates to a process for the continuous production of acrylic acid, in the absence of organic solvent and in the absence of chemical treatment of the aldehydes, and without employing a dividing-wall column, from a gaseous reaction mixture comprising acrylic acid obtained by gas-phase oxidation of a precursor of acrylic acid.

The present invention provides a method for efficiently producing a nucleic acid oligomer. Specifically, the present invention provides a method for producing a nucleic acid oligomer represented by Formula (2), the method including a step of reacting a nucleic acid oligomer represented by Formula (1) with a dichloroacetic acid solution having a molar ratio of formaldehyde to dichloroacetic acid (formaldehyde mol/dichloroacetic acid mol) of 90×10.sup.−6 or less:

##STR00001## wherein symbols have the meanings given in the description;

##STR00002## wherein symbols have the meanings given in the description.

The present invention provides a method for efficiently producing a nucleic acid oligomer. Specifically, the present invention provides a method for producing a nucleic acid oligomer represented by Formula (2), the method including a step of reacting a nucleic acid oligomer represented by Formula (1) with a dichloroacetic acid solution having a molar ratio of formaldehyde to dichloroacetic acid (formaldehyde mol/dichloroacetic acid mol) of 90×10.sup.−6 or less:

##STR00001## wherein symbols have the meanings given in the description;

##STR00002## wherein symbols have the meanings given in the description.

Disclosed is a method for linkage recovery of an organic acid in an aqueous organic acid solution. The method comprises: mixing a solution with an organic acid concentration lower than 20 wt % with a specific extractant and then subjecting same to counter-current extraction so as to obtain an extract phase and a raffinate phase; and subjecting the extract phase together with a solution with an acid concentration higher than 70 wt % to an azeotropic rectification so as to recover an organic acid. When the concentration of the aqueous organic acid solution is 20 wt %-70 wt %, the aqueous organic acid solution is extracted and concentrated to make the concentration of the aqueous organic acid solution higher than 70 wt %.

Disclosed is a method for linkage recovery of an organic acid in an aqueous organic acid solution. The method comprises: mixing a solution with an organic acid concentration lower than 20 wt % with a specific extractant and then subjecting same to counter-current extraction so as to obtain an extract phase and a raffinate phase; and subjecting the extract phase together with a solution with an acid concentration higher than 70 wt % to an azeotropic rectification so as to recover an organic acid. When the concentration of the aqueous organic acid solution is 20 wt %-70 wt %, the aqueous organic acid solution is extracted and concentrated to make the concentration of the aqueous organic acid solution higher than 70 wt %.

Disclosed is a method for linkage recovery of an organic acid in an aqueous organic acid solution. The method comprises: mixing a solution with an organic acid concentration lower than 20 wt % with a specific extractant and then subjecting same to counter-current extraction so as to obtain an extract phase and a raffinate phase; and subjecting the extract phase together with a solution with an acid concentration higher than 70 wt % to an azeotropic rectification so as to recover an organic acid. When the concentration of the aqueous organic acid solution is 20 wt %-70 wt %, the aqueous organic acid solution is extracted and concentrated to make the concentration of the aqueous organic acid solution higher than 70 wt %.

The present disclosure provides azeotrope or azeotrope-like compositions including trifluoroiodomethane (CF.sub.3I) and trifluoroacetyl chloride (CF.sub.3COCl), and a method of forming an azeotrope or azeotrope-like composition comprising the step of combining trifluoroacetyl chloride (CF.sub.3COCl) and trifluoroiodomethane (CF.sub.3I) to form an azeotrope or azeotrope-like composition.

The present disclosure provides azeotrope or azeotrope-like compositions including trifluoroiodomethane (CF.sub.3I) and trifluoroacetyl chloride (CF.sub.3COCl), and a method of forming an azeotrope or azeotrope-like composition comprising the step of combining trifluoroacetyl chloride (CF.sub.3COCl) and trifluoroiodomethane (CF.sub.3I) to form an azeotrope or azeotrope-like composition.