1.1 Porphyrins - Friedrich-Alexander-Universität Erlangen-Nürnberg

6 Experimental Section
6.2.4 AB3-Type Mono-Exocyclic Cycloketo-Porphyrins and Their
146
Precursors
6.2.4.1 2-(Bromomethyl)-4-t-Butyl-6-Methyl-Bromobenzene, 36a, and 2,6-Bis-
Br
(Bromomethyl)-4-t-Butyl-Bromobenzene, 36b – Optimized Protocols
In a three-necked round bottom flask, suitable for
external irradiation, equipped with a dropping funnel
and a reflux condenser closed by a one-hole stopper
with exhaust duct, 30.0 g (94 mmol) of 4-t-butyl-2,6-
dimethyl-bromobenzene 35 are dissolved in CH2Cl2
(150 mL). Then a solution of bromine, Br2, in 10 mL of
CH2Cl2 is added dropwise under irradiation with a 500 W halogen lamp avoiding the reaction
mixture becoming too intensely colored. For the synthesis of 36a, 0.8 eq. of Br2 (3.8 mL,
74 mmol) are used while for 36b 1.25 eq. (6.0 mL, 117 mmol) are necessary. After completed
addition, the irradiation is continued until the reaction mixture becomes almost colorless.
Then, the HBr dissolved in the reaction mixture is expelled by utilization of a stream of
compressed-air or nitrogen for at least 15 min. Subsequently, the mixture is transferred into
a separatory funnel and shaken out with 100 mL of an aqueous solution of NaOH (1 M). The
organic layer is separated, washed with water, dried over MgSO4 and the solvent is removed
under reduced pressure. FC (silica, hexanes as eluent) gives the desired compounds as white
crystalline solids: 16.5 g for 36a (42 % yield based on 35) and 21.8 g for 36b (58 % yield
based on 35), respectively.
1 H NMR (36a, 300 MHz, rt, CDCl3): δ [ppm] = 1.30 (s, 9 H, t-BuH), 2.42 (s, 3 H, ArCH3), 4.64 (s,
2 H, CH2Br), 7.21 (d, 4 J = 2.3 Hz, 1 H, ArH), 7.29 (d, 4 J = 2.3 Hz, 1 H, ArH).
13 C NMR (36a, 75.5 MHz, rt, CDCl3): δ [ppm] = 24.0, 31.1, 34.4, 35.2, 123.8, 125.8, 128.4,
136.6, 138.7, 150.4.
MS (36a, FAB+, NBA): m/z (%) = 320 (100) [M] +· , 239 (60) [M-Br] +· .
1 H NMR (36b, 300 MHz, rt, CDCl3): δ [ppm] = 1.30 (s, 9 H, t-BuH), 4.62 (s, 2 H, CH2Br), 7.39 (s,
2 H, ArH).
Br
C 12 H 16 Br 2
M = 320.06 g·mol -1
Br
Br
36a 36b
Br
C 12 H 15 Br 3
M = 398.96 g·mol -1
13 C NMR (36b, 75.5 MHz, rt, CDCl3): δ [ppm] = 31.1, 34.4, 34.6, 123.4, 128.7, 137.7, 151.3.