Nitric Acid → 2,3-Dichloro-5-nitrobenzoic acid

HRID 2427202Notes

Reaction equation

HRID 2427202 reaction equation
[Cl:1][C:2]1[C:10]([Cl:11])=[CH:9][CH:8]=[CH:7][C:3]=1[C:4]([OH:6])=[O:5].[N+:12]([O-])([OH:14])=[O:13]>OS(O)(=O)=O>[Cl:1][C:2]1[C:10]([Cl:11])=[CH:9][C:8]([N+:12]([O-:14])=[O:13])=[CH:7][C:3]=1[C:4]([OH:6])=[O:5]

Participants

4

Reactant 2

HCID 944Nitric AcidHCID 57652,3-Dichlorobenzoic acid2×

Product 1

HCID 221488012,3-Dichloro-5-nitrobenzoic acidYield 44%

Reagents, catalysts & solvents 1

HCID 1118Sulfuric AcidSolvent2×

Conditions

Temperature
0 °C

Procedure

2,3-Dichlorobenzoic acid, obtained from Aldrich, (40 g, 0.21 mole) was added portion wise to a −20° C. concentrated H2SO4, obtained from Acros, (233 mL) solution which was fitted with a mechanical overhead stirrer. During the addition process, a separate flask containing concentrated H2SO4 (50 mL) was cooled to 0° C. and fuming HNO3, obtained from Acros, (16.6 mL) was slowly added. This solution was then added dropwise to the 2,3-Dichlorobenzoic acid solution at a rate which kept the reaction mixture at or slightly below −15° C. After the addition was complete the resulting solution was allowed to warm to 10° C. over 3 hours. The crude solid material was filtered through a fitted filter funnel, washed with cold H2O (200 mL), and dried under a stream of air followed by high vacuum to yield 21.7 g (44%) of product (246) which contained 4% of the undesired regioisomer (2,3-Dichloro-6-nitrobenzoic acid 247) based on 1H NMR analysis. The filtrate was slowly poured over ice and additional solid precipitated. This solid was observed to be a 3:1 mixture of 2,3-dichloro-6-nitrobenzoic acid (247) to 2,3-dichloro-5-nitrobenzoic acid (246) based on 1H NMR analysis.

Workup

  1. customwas fitted with a mechanical overhead stirrer
  2. additionwas slowly added
  3. customslightly below −15° C
  4. additionAfter the addition
  5. temperatureto warm to 10° C. over 3 hours
  6. filtrationThe crude solid material was filtered through a fitted
  7. filtrationfilter funnel
  8. washwashed with cold H2O (200 mL)
  9. customdried under a stream of air

Sources & evidence

ORD record
ord-d9831457d7cd4f27a42ff2032d0a528c
Source dataset
uspto-grants-2011_06
Patent number
US07968567B2

Reaction notes

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