Sulfuric Acid → Sulfuric Acid

HRID 898642Notes

Reaction equation

HRID 898642 reaction equation
C1(=NO)CCCCC1.[S:9](=[O:13])(=[O:12])([OH:11])[OH:10].[C:14]1(=[O:21])[NH:20][CH2:19][CH2:18][CH2:17][CH2:16][CH2:15]1>>[C:14]1(=[O:21])[NH:20][CH2:19][CH2:18][CH2:17][CH2:16][CH2:15]1.[S:9](=[O:11])(=[O:10])([OH:13])[OH:12].[S:9](=[O:12])(=[O:11])=[O:10]

Participants

6

Reactant 3

HCID 1118Sulfuric Acid4×HCID 7517Cyclohexanone OximeHCID 7768Caprolactam4×

Product 3

HCID 1118Sulfuric AcidHCID 7768CaprolactamHCID 24682Sulfur trioxide

Procedure

Such a process is for example described in U.S. Pat. No. 3,914,217. In the process as described in U.S. Pat. No. 3,914,217 the Beckmann rearrangement is carried out in three stages in series. Cyclohexanone oxime is fed to each stage containing a circulating rearrangement mixture having a sulfuric acid+SO3 to caprolactam weight ratio and a SO3 content within certain ranges. The circulating rearrangement mixture of the first stage has a sulfuric acid+SO3 to caprolactam weight ratio of 1.33 to 1.80 (molar ratio of 1.55 to 2.17) and a SO3 content of 2 to 14 wt. %; the circulating rearrangement mixture of the second stage has a sulfuric acid+SO3 to caprolactam weight ratio of 1.14 to 1.31 (molar ratio of 1.32 to 1.55) and a S03 content of at least 0.82 wt. %, preferably 0.82 to 6.5 wt. % and the circulating rearrangement mixture of the third stage has a sulfuric acid+SO3 to caprolactam weight ratio of 1.00 to 1.13 (molar ratio of 1.15 to 1.33) and a SO3 content of at least 0.4 wt. %, preferably 0.4 to 4 wt. %. The reaction mixture obtained in the third rearrangement stage essentially containing caprolactam, sulfuric acid and optionally residual sulfur trioxide is sent to a reactor system together with ammonia, water and a solvent such as toluene. The sulfuric acid and SO3 are neutralized by converting the sulfuric acid and SO3 into ammonium sulfate and the caprolactam is simultaneously extracted from the ammonium sulfate solution formed in this system.

Workup

  1. additioncontaining a circulating rearrangement mixture
  2. additionThe circulating rearrangement mixture of the first stage
  3. additionthe circulating rearrangement mixture of the second stage
  4. additiona S03 content of at least 0.82 wt. %, preferably 0.82 to 6.5 wt. % and the circulating rearrangement mixture of the third stage

Sources & evidence

ORD record
ord-19faabab765243eb848681620c1afbf3
Source dataset
uspto-grants-2008_04
Patent number
US07351820B2

Reaction notes

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