Hydrochloric Acid → 1,4-Dihydro-6-methylquinoxaline-2,3-dione

HRID 1781035Notes

Reaction equation

[NH2:1][C:2]1[CH:3]=[C:4]([CH3:9])[CH:5]=[CH:6][C:7]=1[NH2:8].Cl.O.O.[C:13](O)(=[O:17])[C:14](O)=[O:15].[OH-].[Na+]>>[CH3:9][C:4]1[CH:3]=[C:2]2[C:7](=[CH:6][CH:5]=1)[NH:8][C:14](=[O:15])[C:13](=[O:17])[NH:1]2

Participants

Reactant 4

HCID 313Hydrochloric Acid2×

HCID 103323,4-Diaminotoluene

HCID 14798Sodium Hydroxide

HCID 61373Oxalic acid dihydrate

Product 1

HCID 732251,4-Dihydro-6-methylquinoxaline-2,3-dioneYield 518.2%

Conditions

Temperature: 25 °C

Procedure

To a stirred solution of 3,4-diaminotoluene (0.302 g, 0.247 mmol, Aldrich) in 2N HCl (4 mL, 8 mmol), oxalic acid dihydrate (0.330 g, 0.261 mmol, Fisher) was added in one portion. The resulting deep purple solution was refluxed for 13 h, to give a purple suspension. This was cooled to 25° C., filtered, washed with water (5 mL), and dried in vacuo (0.1 mm Hg) to give a blue-grey powder. This was taken up in 2N NaOH (34 mL, 68 mmol), giving a brown solution, which was filtered. The brown filtrate was acidified to pH 1.0 by addition of 2N HCl (42 mL, 84 mmol), resulting in a tan suspension. Filtration of the suspension and washing of the filter cake with water (5 mL) gave the title compound as a grey powder (225.5 mg, 43%); mp 318° C. (the block was preheated to 300° C.); 1H NMR (DMSO-d6) δ2.32 (s, 3H), 6.90-6.99 (m, 3H), 11.22 (s, 1H), 11.90 (s, 1H).

Workup

temperatureThe resulting deep purple solution was refluxed for 13 h
customto give a purple suspension
filtrationfiltered
washwashed with water (5 mL)
customdried in vacuo (0.1 mm Hg)
customto give a blue-grey powder
customgiving a brown solution, which
filtrationwas filtered
customresulting in a tan suspension
filtrationFiltration of the suspension
washwashing of the filter cake with water (5 mL)

Sources & evidence

ORD record: ord-12fa4b7545e24913ba70142a23da9b9f
Source dataset: uspto-grants-1997_05
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US05631373

Reaction notes

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