4,7-Dimethyl-3a,4,7,7a-tetrahydro-4,7-epoxy-2-benzofuran-1,3-dione → 3,6-Dimethylphthalic anhydride

HRID 1879523Notes

Reaction equation

HRID 1879523 reaction equation
[CH3:1][C:2]12O[C:8]([CH3:12])([CH:9]=[CH:10]1)[CH:7]1[CH:3]2[C:4](=[O:14])[O:5][C:6]1=[O:13]>S(=O)(=O)(O)O>[CH3:12][C:8]1[CH:9]=[CH:10][C:2]([CH3:1])=[C:3]2[C:7]=1[C:6](=[O:13])[O:5][C:4]2=[O:14]

Participants

3

Reactant 1

HCID 2450364,7-Dimethyl-3a,4,7,7a-tetrahydro-4,7-epoxy-2-benzofuran-1,3-dione

Product 1

HCID 216163,6-Dimethylphthalic anhydrideYield 42.1%

Reagents, catalysts & solvents 1

HCID 1118Sulfuric AcidSolvent

Conditions

Temperature
-5 °C

Procedure

1,7-Dimethyl-4,10-dioxa-tricyclo[5.2.1.0]dec-8-ene-3,5-dione 1 (30.0 g, 0.150 mol) is added slowly in portions to stirred 98% sulfuric acid (300 mL) in a 1 L flange flask cooled to −5° C. using a salt-ice bath—note that the temperature is kept below 0° C. during the addition. The mixture is stirred for 30 mins at −5° C. and then allowed to warm up to 22° C. The mixture is carefully poured onto crushed ice (1.5 L). The cream precipitate that formed is filtered off and washed with ice water. The precipitate is dissolved in a 5% aq. sodium hydroxide solution (225 mL) with stirring. Glacial acetic acid (20 mL) is added slowly to the stirred solution. A cream precipitate forms and this is filtered off and discarded. 37% Hydrochloric acid (50 mL) is added to the stirred filtrate and the mixture is stirred for 2 h during which time a precipitate is formed. The precipitate is filtered off and dried in the vacuum oven overnight to yield the product as a cream solid (11.13 g, 41%). The filtrate is allowed to stand overnight during which time further product precipitated out. The second crop of precipitate is filtered off and dried under vacuum to yield the product 2 as a cream solid (5.79 g, 21%): 1H-NMR (300 MHz, CDCl3) δ 7.18 (s, 2H), 2.40 (s, 6H).

Workup

  1. additionis kept below 0° C. during the addition
  2. temperatureto warm up to 22° C
  3. additionThe mixture is carefully poured
  4. customThe cream precipitate that formed
  5. filtrationis filtered off
  6. washwashed with ice water
  7. dissolutionThe precipitate is dissolved in a 5% aq. sodium hydroxide solution (225 mL)
  8. stirringwith stirring
  9. additionGlacial acetic acid (20 mL) is added slowly to the stirred solution
  10. filtrationA cream precipitate forms and this is filtered off
  11. addition37% Hydrochloric acid (50 mL) is added to the stirred filtrate
  12. stirringthe mixture is stirred for 2 h during which time a precipitate
  13. customis formed
  14. filtrationThe precipitate is filtered off
  15. customdried in the vacuum oven overnight

Sources & evidence

ORD record
ord-e035f866252c4440b2884f72c10b0119
Source dataset
uspto-grants-2012_11
Patent number
US08318048B2

Reaction notes

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