Isomer-selective synthesis of methanofullerenes
View Patent ↗[6,6]-Phenyl C 71 butyric acid derivatives (C 70 -PCBR 3 ) having a selectivity of greater than 95 wt % of the α-isomer are provided by reacting fullerene C 70 with a dialkyl sulfonium tetrafluoroborate having the formula:
1. A method of making [6,6]-Phenyl C 71 butyric acid methyl ester comprising:
reacting fullerene C 70 with a dialkyl sulfonium salt having the formula:
where R 1 and R 2 are iso-propyl; R 3 is methyl; and X an anion selected from Br − , I − , Cl − , F − , BF 4 − , PF 6 − , SbF 6 − , AsF 6 − , OSO 2 CH 3 − , OSO 2 CF 3 − , OSO 2 C 4 F 9 − , OSO 2 OCH 3 − , OCOCH 3 − , OCOCF 3 − , OSO 2 (C 6 H 4 )CH 3 − , OSO 2 (C 6 H 4 )CF 3 − , N(SO 2 CF 3 ) 2 − , OSO 2 CH 2 CH 2 CH 2 CH 2 SO 2 O − —, OH − , I 3 − , N(CN) 2 − , 7,7-dimethyl-2-oxobicyclo[2.2.1]heptane-1-methanesulfonate, B(C 6 H 5 ) 4 − or OSO 2 OH − ,
to provide [6,6]-Phenyl C 71 butyric acid methyl ester (C 70 -PCBM) comprising greater than 97 wt % of the α-isomer.
2. The method of claim 1 , wherein the reaction provides greater than 98 wt % selectivity of the α-isomer.
3. The method of claim 1 , further comprising reacting the fullerene C 70 and the dialkyl sulfonium tetrafluoroborate in the presence of a base.
4. The method of claim 3 , wherein the base comprises an organic base.
5. The method of claim 4 , wherein the base comprises 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).
6. The method of claim 1 , wherein the dialkyl sulfonium salt has the formula:
where R 1 ═R 2 =iso-propyl.
7. [6,6]-Phenyl C 71 butyric acid methyl ester (C 70 -PCBM) comprising greater than 98% of the α-isomer.
8. [6,6]-Phenyl C 71 butyric acid methyl ester (C 70 -PCBM) comprising greater than 99% of the α-isomer.