Reaction #1144444

Reaction equation

2-Ethylhexyl bromide

2,7-dichlorofluorene

sodium hydroxide

2,7-dichlorofluorene

dimethylsulfoxide

2-ethylhexyl bromide

→

2,7-dichloro-9,9-di(2-ethylhexyl)-fluorene

Yield 94.0%

Solvents

diethyl ether

Water

Conditions

Workup

1. 1
   workup.WAITthe temperature reaching 80° C. within 5 minutes
2. 2
   Otherfalling off to 30° C. over the 2-hour reaction time
3. 3
   workup.STIRRINGstirred for 15 minutes
4. 4
   Otherthe layers are separated
5. 5
   WashThe organic layer is washed with a saturated aqueous NaCl solution, water
6. 6
   Dryingdried (MgSO4)
7. 7
   Otherevaporated
8. 8
   Otherto remove ether
9. 9
   workup.DISTILLATIONFractional vacuum distillation of the residue

Procedure

To a stirred mixture of 2,7-dichlorofluorene (43 g, 0.183 mole) and 120 mL of dimethylsulfoxide (DMSO) under nitrogen is added benzyltriethylammonium chloride (2.3 g, 0.01 mole) and 60 mL of a 50 weight percent aqueous solution of sodium hydroxide. 2-Ethylhexyl bromide (85 g, 0.44 mole) is added and the mixture is agitated well for 2 hours. The reaction is exothermic, the temperature reaching 80° C. within 5 minutes after the addition of 2-ethylhexyl bromide and then falling off to 30° C. over the 2-hour reaction time. Analysis of an aliquot by high pressure liquid chromatography (HPLC) shows the complete disappearance of 2,7-dichlorofluorene and the formation of new product. Water (200 mL), and diethyl ether (250 mL) are added to the reaction mixture, stirred for 15 minutes and the layers are separated. The organic layer is washed with a saturated aqueous NaCl solution, water, dried (MgSO4) and evaporated to remove ether. Fractional vacuum distillation of the residue provides 2,7-dichloro-9,9-di(2-ethylhexyl)-fluorene as clear liquid, boiling point 200° C./1 mm Hg, (79 g, 94 percent yield); HPLC analysis shows that the product is 99 percent pure. Proton Magnetic Spectrum (PMR) analysis is consistent with the title structure.

Source