Hydrochloric Acid → 4-methyl-1-oxo-1H-2-benzothiopyran-3-carboxylic acid

HRID 1657482Notes

Reaction equation

HRID 1657482 reaction equation
[C:1]([C:4]1[CH:18]=[CH:17][CH:16]=[CH:15][C:5]=1[C:6](=[C:8]1[S:12]C(=S)N[C:9]1=[O:14])[CH3:7])([OH:3])=O.[OH-:19].[Na+].Cl>>[CH3:7][C:6]1[C:5]2[CH:15]=[CH:16][CH:17]=[CH:18][C:4]=2[C:1](=[O:3])[S:12][C:8]=1[C:9]([OH:19])=[O:14]

Participants

4

Reactant 3

HCID 313Hydrochloric AcidHCID 14798Sodium HydroxideHCID 737934855-(2-Carboxy-alpha-methylbenzylidene)rhodanine

Product 1

HCID 214236814-methyl-1-oxo-1H-2-benzothiopyran-3-carboxylic acid

Procedure

A stirred solution of 2.00 g. (7.17 mM) of the carboxylic acid of Example 13 in 15 ml. of 15% sodium hydroxide is refluxed for 0.75 hour, cooled, and poured into dilute hydrochloric acid, whereupon a precipitate forms. The solid is collected and recrystallized from ethyl acetate-hexane to give a tan solid. This solid is heated briefly to 245°, cooled, and the residue recrystallized from ethyl acetatehexane to give 4-methyl-1-oxo-1H-2-benzothiopyran-3-carboxylic acid as tan crystals, m.p. 247°-248°.

Workup

  1. temperaturecooled
  2. customThe solid is collected
  3. customrecrystallized from ethyl acetate-hexane
  4. customto give a tan solid
  5. temperatureThis solid is heated briefly to 245°
  6. temperaturecooled
  7. customthe residue recrystallized from ethyl acetatehexane

Sources & evidence

ORD record
ord-513cb3ce2a874ef6be4525746c095af7
Source dataset
uspto-grants-1976_06
Patent number
US03960892

Reaction notes

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