1,5-DICHLORO-2,4-DIFLUOROBENZENE

Conditions: temp:200.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 3 kg (15.5 mol) of iron-free, dry 5-chloro-2,4-difluoronitrobenzene are introduced into a 2 l four-necked flask with stirrer, dropping funnel and gas inlet tube and, on top, a column with reflux condenser. After heating the reaction solution to 200° C., chlorine is passed through the solution at a rate of 15 l/h. After 4-6 hours, the solution begins to boil, and after a further 2-4 hours the 1,3-dichloro-4,6-difluorobenzene which is formed can be taken off at the head of the column. At the same time, fresh 5-chloro-2,4-difluoronitrobenzene is added to the reaction in accordance with the quantity of product removed. on top, a column with reflux condenser

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: By nitration of 1,3-dichloro-4,6-difluorobenzene, the 2,6-dichloro-3,5-difluoronitrobenzene is available after stage 3 in good yields (75-95%) and selectivities (87:12; 3,5-difluoro-2,6-dichloronitrobenzene:2,6-difluoro-3,5-dichloronitrobenzene). (See also Trans. Ill. State Acad. Sci., 65, (1972) 75-80).

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: By nitration of 1,3-dichloro-4,6-difluorobenzene, the 2,6-dichloro-3,5-difluoronitrobenzene is available after stage 3 in good yields (75-95%) and selectivities (87:12; 3,5-difluoro-2,6-dichloronitrobenzene:2,6-difluoro-3,5-dichloronitrobenzene). (See also Trans. Ill. State Acad. Sci., 65, (1972) 75-80).

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A synthesis proceeding via four stages can be taken from EP 562 435. 2,4,5-Trichloronitrobenzene is first reacted with an alkali metal fluoride to give 5-chloro-2,4-difluoronitrobenzene. By means of chlorinating denitration the 5-chloro-2,4-difluoronitrobenzene can be converted to 1,3-dichloro-4,6-difluorobenzene. The 1,3-dichloro-4,6-difluorobenzene is nitrated to give 2,6-dichloro-3,5-difluoronitrobenzene. The desired 3,5-difluoroaniline can be prepared from the 2,6-dichloro-3,5-difluoronitrobenzene by reaction with hydrogen with elimination of hydrogen chloride and reduction of the nitro group.

Conditions: temp:200.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 3 kg (15.5 mol) of iron-free, dry 5-chloro-2,4-difluoronitrobenzene are introduced into a 2 l four-necked flask with stirrer, dropping funnel and gas inlet tube and, on top, a column with reflux condenser. After heating the reaction solution to 200° C., chlorine is passed through the solution at a rate of 15 l/h. After 4-6 hours, the solution begins to boil, and after a further 2-4 hours the 1,3-dichloro-4,6-difluorobenzene which is formed can be taken off at the head of the column. At the same time, fresh 5-chloro-2,4-difluoronitrobenzene is added to the reaction in accordance with the quantity of product removed. on top, a column with reflux condenser

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: By nitration of 1,3-dichloro-4,6-difluorobenzene, the 2,6-dichloro-3,5-difluoronitrobenzene is available after stage 3 in good yields (75-95%) and selectivities (87:12; 3,5-difluoro-2,6-dichloronitrobenzene:2,6-difluoro-3,5-dichloronitrobenzene). (See also Trans. Ill. State Acad. Sci., 65, (1972) 75-80).