Hydrochloric Acid → 2-Methyl-7-chlorosulfonylbenzothiazole

HRID 236238Notes

Reaction equation

[CH3:1][C:2]1[S:3][C:4]2[C:10](N)=[CH:9][CH:8]=[CH:7][C:5]=2[N:6]=1.N([O-])=O.[Na+].[S:16](=[O:18])=[O:17].[ClH:19]>O.C(O)(=O)C>[CH3:1][C:2]1[S:3][C:4]2[C:10]([S:16]([Cl:19])(=[O:18])=[O:17])=[CH:9][CH:8]=[CH:7][C:5]=2[N:6]=1

Participants

Conditions

Temperature: 0 °C

Procedure

A suspension of 8 g of the product from Example 7 in 20 mL of concentrated hydrochloric acid was cooled to 0° C. and treated with a solution of 3.7 g sodium nitrite in 6 mL of water. After completion of the addition, the mixture was stirred at 0°-5° C. for about 15 minutes. This diazonium salt solution was then added all at once to a mixture of liquid sulfur dioxide, 2 g of cupric chloride dihydrate, and 4 mL water in 39 mL of glacial acetic acid at about 10° C.; vigorous gas evolution ensued. This reaction mixture was stirred at room temperature for another 4 hours, and was then poured into 190 mL ice-water. The resulting precipitate was collected by filtration, washed with water, and dried to give 9.2 g of 2-methyl-7-chlorosulfonylbenzothiazole as a yellow powder, m.p. 93°-97° C., dec; IR(KBr): 1380, 1175, 800, 770, 720 cm-1.

Workup

additionAfter completion of the addition
stirringThis reaction mixture was stirred at room temperature for another 4 hours
filtrationThe resulting precipitate was collected by filtration
washwashed with water
customdried

Sources & evidence

ORD record: ord-f3e2354a16784de7a0e05f44d5ee1058
Source dataset: uspto-grants-1987_02
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US04643759

Reaction notes

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