Ethanol → Ethyl 5-methyl-2-thiophenecarboxylate

HRID 900984Notes

Reaction equation

HRID 900984 reaction equation
[CH3:1][C:2]1[S:6][C:5]([C:7]([OH:9])=[O:8])=[CH:4][CH:3]=1.OS(O)(=O)=O.[CH3:15][CH2:16]O>>[CH2:15]([O:8][C:7]([C:5]1[S:6][C:2]([CH3:1])=[CH:3][CH:4]=1)=[O:9])[CH3:16]

Participants

4

Reactant 3

HCID 702EthanolHCID 1118Sulfuric AcidHCID 747135-Methylthiophene-2-carboxylic acid

Product 1

HCID 11019293Ethyl 5-methyl-2-thiophenecarboxylateYield 85%

Procedure

A solution of 5-methyl-thiophene-2-carboxylic acid (25.2 g, 177 mmol) in EtOH (500 mL) is treated with conc. H2SO4 (15 mL) and heated to a gentle reflux for 72 h. The solution is partially concentrated and poured into water (500 mL) and extracted with Et2O (3×). The combined extracts are washed with aq Na2CO3, water, dried over Na2SO4, filtered and concentrated in vacuo. Vacuum distillation of the residue afforded 5-methyl-thiophene-2-carboxylic acid ethyl ester (25.6 g, 85%): bp 98-99° C./9-10 mbar; 1H NMR (CDCl3, 300 MHz) δ 7.6 (s, 1 H), 6.78 (s, 1 H), 4.30 (q, J=6.0 Hz, 2 H), 2.50 (s, 3 H), 1.34 (t, J=6.0 Hz, 3 H).

Workup

  1. temperatureheated to
  2. temperaturea gentle reflux for 72 h
  3. concentrationThe solution is partially concentrated
  4. additionpoured into water (500 mL)
  5. extractionextracted with Et2O (3×)
  6. washThe combined extracts are washed with aq Na2CO3, water
  7. dry with materialdried over Na2SO4
  8. filtrationfiltered
  9. concentrationconcentrated in vacuo
  10. distillationVacuum distillation of the residue

Sources & evidence

ORD record
ord-db7050dab15f44e49e8885329abd5c99
Source dataset
uspto-grants-2008_04
Patent number
US07361671B2

Reaction notes

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