Claims
- 1. In a process for preparing a 2-hydrocarbylthioaldoxime of the formula ##STR13## where R' and R" independently are alkyl of 1 to 4 carbons, and R''' is a hydrocarbon radical of 1 to 18 carbon atoms selected from the group consisting of alkyl, cycloalkyl, alkenyl, cycloalkenyl and aryl or a substituted hydrocarbon radical of the above group, said process comprising the halogenation under reflux conditions of an unhalogenated aldehyde of the formula ##STR14## with a halogenating agent selected from Cl.sub.2, Br.sub.2 and I.sub.2, to form an .alpha.-haloaldehyde of the formula ##STR15## where X is Cl, Br or I and R' and R" are as defined above, and the thiohydrocarbylation of said .alpha.-haloaldehyde with a thiol salt of the formula R'''SM, where R''' is as defined above and M is an alkali or alkaline earth metal to form an .alpha.-formyl sulfide of the formula ##STR16## and the oximation of the said .alpha.-formyl sulfide to form said 2-hydrocarbylthioaldoxime, the improvement wherein the halogenation under reflux conditions of the unhalogenated aldehyde comprises continuously feeding the unhalogenated aldehyde and halogenating agent into a reactor at a molar ratio of halogenating agent to unhalogenated aldehyde of between about 0.8:1 and about 1.1:1 and continuously feeding water into the reactor at a rate of between about 1% and about 20% by weight of unhalogenated aldehyde and wherein the thiohydrocarbylation step includes reacting an .alpha.-haloaldehyde having less than about 1% by weight of homopolymers and copolymers of unreacted unhalogenated aldehyde.
- 2. The process of claim 1 wherein the halogenation agent is Cl.sub.2.
- 3. The process of claim 2 wherein the unhalogenated aldehyde is isobutyric aldehyde.
- 4. The process of claim 3 wherein the unhalogenated aldehyde and halogenating agent are fed at a molar ratio of halogenating agent to unhalogenated aldehyde of between about 0.95:1 and about 1.0:1 and water is fed at a rate of between about 2% and about 10% by weight of unhalogenated aldehyde.
- 5. The process of claim 2 wherein the halogenation reaction mass is sufficiently large and the unhalogenated aldehyde feed rate sufficiently small to maintain the unhalogenated aldehyde concentration of the reaction mass below about 3% by weight.
- 6. The process of claim 2 wherein the halogenation reaction mass is sufficiently large and the unhalogenated aldehyde feed rate sufficiently small to maintain the unhalogenated aldehyde concentration of the reaction mass below about 1% by weight.
- 7. The process of claim 3 wherein .alpha.-haloaldehyde being .alpha.-chloroisobutyraldehyde is continuously withdrawn from the reactor and distilled once to remove lites and a second time to distill the .alpha.-haloaldehyde from residues.
- 8. The process of claim 7 wherein the distilled .alpha.-haloaldehyde is then stored at between about 60.degree. C. and about 90.degree. C.
- 9. The process of claim 7 wherein the distilled .alpha.-haloaldehyde is purged of dissolved HCl by sparging with an inert gas.
- 10. The process of claim 7 wherein the .alpha.-formyl sulfide is distilled once to remove lites and a second time to distill .alpha.-formyl sulfide from residues.
- 11. The process of claim 7 wherein the oximation step comprises reacting the .alpha.-formyl sulfide with hydroxylamine sulfate and a base and recovering an aqueous sulfate salt solution.
- 12. The process of claim 11 wherein said base is ammonia and said aqueous salt solution is an ammonium sulfate solution.
- 13. The process of claim 11 wherein the reacting and recovering portions of the oximation step are conducted in stainless steel vessels.
Parent Case Info
This is a division of Application Ser. No. 821,898, filed Aug. 4, 1977, now U.S. Pat. No. 4,096,187.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
3873624 |
Mathew et al. |
Mar 1975 |
|
Non-Patent Literature Citations (2)
Entry |
Guinot et al., Compt. Rend. vol. 231, pp. 234-236 (1950). |
Hagemeyer et al., "The Chemistry of Isobutyraldehyde and its Derivatives", pp. 1, 5, 10-15, 48-49, 61, 85, 87-94 (1953). |
Divisions (1)
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Number |
Date |
Country |
Parent |
821898 |
Aug 1977 |
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