Patented July 6, 19.43 2,323,594

UNITED‘ STATES PATENT ‘OFFICE 2,323,594 PEODUOI‘ION 0F OHLORINE DIOXIDE BY REACTION OF CHLORITES AND AIDE HYDES Clifford A. Hampel, Niagara Falls, N. Y., assignor to The Mathieson Alkali Works, Inc., New York, N. Y., a corporation of Virginia No Drawing. Application October 29, 1941, Serial No. 411,001 10 Claims. (01. 2s-152) My invention relates to improvements in the water vapor, in a diluent such as air or nitrogen, production of chlorine dioxide. I have dis can be passed through a solid chlorite to produce covered that chlorites react with aldehydes, under chlorine dioxide carried from the reaction in the appropriate conditions, to form chlorine dioxide. diluent. ’ The reaction is surprising since aldehydes, nor The following examples will further illustrate mally reducing agents, could not be expected to my invention: oxidize chloiites to chlozine dioxide. The re Example I action cannot be accounted for by assuming that the aldehyde is oxidized, by a part of the chlorite, One gram of paraformaldehyde and 1 gram of to the corresponding acid which in turn acts upon sodium chlorite (98% NaClOz) were added to another part of the chlorite to form chlorine di 100 cc.‘ of water and the solution was heated to oxide since the aldehyde-chlorite reaction will 50° C. 0.25 gram of chlorine dioxide was gener occur in bu?‘e'red solutions above the pH value at ated. which the acid chlorite reaction occurs. The Example II reaction may involve auto-oxidation of the 15 A solution containing 1.15 grams (0.0127 moles) ' chlorite induced by the aldehyde or it may be a of sodium chlorite in 145 cc. of water, bu?ered coupled reaction in which the aldehyde reacts with a phosphate buffer at a pH of 7.0, was placed and is reformed. In general, the yields secured in a closed reaction vessel. 0.5 cc. of an aqueous suggest that the-reaction may be typi?ed by the solution of formaldehyde containing 36.6% following equation: 20 formaldehyde was added to this chlorite solu tion. Nitrogen was passed through the com bined solution, while a temperature However, I predicate my invention not upon these of 25° C., for 25 minutes. The gas mixture from or any other explanations. the reaction vessel was passed through two ab According to my invention, chlorine dioxide is 25 sorption towers, the ?rst containing an aqueous produced by reacting a chlorite with an aldehyde solution of sodium hydroxide, 10% NaOH, and in the presence of water at a pH below about 9. - the second containing an aqueous CaOz slurry. The chlorites useful in carrying out my inven The chlorine dioxide generated was recovered in tion comprise the chlorite_s of the alkali metals the scrubbing towers. 92.8% (0.01175 mole) of and of the alkaline earth metals. Aldehydes 30 the sodium chlorite reacted, 23% being converted generally are useful in carrying out my invention, to chlorine dioxide, 26% to sodium chlorate and including straight-chain aliphatic compounds 51% to sodium chloride. Carbon dioxide was which may be typi?ed by formaldehyde and acet formed to the extent of 0.0028 mole. aldehyde, aromatic aldehydes such as benzalde ‘hyde, the heterocyclic aldehydes such as furfural 35 ldramplev III and the aldoses such as dextrose and d-xylose. A solution containing 0.00913 mole of sodium Above a pH of about 9, the reaction tends to form chlorite in 20 cc. of water was charged into a chlorates rather than chlorine dioxide, probably closed reaction vessel connected to two scrubbing through the intermediate formation of chlorine towers as in Example H. 0.00875 mole of formal dioxide reacting in the alkaline medium to form 40 dehyde, as an aqueous 35% formaldehyde solu chlorite and ‘chlorate; Temperature is not criti tion, was added to the solution in the reaction cal, but increasing temperatures increase the re vessel and air was then passed through the com action rate as would be expected. Concentra bined solution, while maintaining a temperature tions are not critical, but increasing concentra of 20° C. for 15 minutes. The pH of the solution tions increase the reaction rate and tend to in at the beginning of the reaction was 7.0 and at crease the proportion of chlorite_ converted to the end was 5.2. 99.8% of the chlorite reacted, chlorine dioxide. The molar ratio of aldehyde to 40% being converted to chlorine dioxide, 16.5% chlorite is not critical, although the proportion of to sodium chlorate and 43.5% to sodium chloride. chlorite reacting decreases if this ratio is below Carbon dioxide was formed to the extent of about 0.6: 1. If this ratio exceeds about 0.6:1, all 50 0.0015 mole. of the chlorite is consumed in the reaction. Pro portions of aldehyde exceeding a molar ratio of Example IV about 1:1 do not seem to a?ect the course or rate One cc. of benzaldehyde was added to 1 gram of of the reaction. The reaction can be conducted sodium chloride in 100 cc. of water, buil'ered at a in aqueous solution, or vaporized aldehyde and 55 pH of ‘7.0. 0.3 gram of chlorine dioxide was 2 2,323,594 generated at 20° C. At the end of the reaction the vapors of an aldehyde in the presence of the benzaldehyde had disappeared‘ as a separate water vapor. phase and the pH- of the solution was 7. 5. In the production of chlorine dioxide, the improvement whichv comprises reacting a chlo Example V , rite of a metal of the group consisting of alkali One cc. of rurfural (technical) was added to metals and alkaline earth metals with an ali 3 grams of sodium chlorite in 100 cc. of water and phatic aldehyde in the presence of water at a the solution was heated to 60° C. Chlorine di pH below about 9. I . oxide was generated. 6. In the production of chlorine dioxide, the 10 improvement which comprises reacting a chlo— Example VI rite of a metal of the group consisting of alkali metals and alkaline earth metals with formalde 0.5 gram of dextrose was added to 1 gram of hyde in the presence of water at a pH below sodium chlorite in 100 cc. of water and the solu about 9. tion was heated to 80° C. Chlorine dioxide was '7. In the production of chlorine dioxide, the generated. improvement which comprises reacting a chlo I claim: rite of a metal of the group consisting of alkali 1. In the production of chlorine dioxide, the metals and alkaline earth metals with a carbo improvement which comprises reacting a chlorite cyclic aldehyde in the presence of water at a of a metal of the group consisting of alkali 20 pH below about 9. metals and alkaline earth metals with an alde 8. In the production of chlorine dioxide, the hyde in the presence of water at a pH below improvement which comprises reacting a chlo about 9. ' rite of a metal of the group consisting of alkali 2. In the production of chlorine dioxide, the metals and alkaline earth metals with benzalde improvement which comprises reacting a chlorite 25 hyde in the presence-of water at a pH below of a metal of the group consisting of alkali met about 9. ' als and alkaline earth metals with an aldehyde 9. In the production of chlorine dioxide. the in the presence of water at a pH below about 9, improvement which comprises reacting a chlo the molar ratio of alheyde to chlorite being at rite of a metal of the group consisting of alkali least 0.6: 1. . 30 metals and alkaline earth metals with a hetero 3. In the production of chlorine dioxide, the cyclic aldehyde in the presence of water at a pH improvement which comprises reacting a chlo below about 9. ' rite of a metal of the group consisting of alkali 10. In the production of chlorine dioxide, the metals and alkaline earth metals with an alde improvement which comprises reacting a chlo hyde in aqueous solution at a pH below about 9. 35 rite of a metal of the group consisting of alkali 4. In the production of chlorine dioxide, the metals and alkaline earth metals with furfural improvement which comprises reacting a solid dehyde in the presence of water at a pH below chlorite of ,a metal of the class consisting of the about 9. alkali metals and the alkaline earth metals with CIJFFORD A. HAMPEL