new index atom name original index 1 C 11 2 C 10 3 C 8 4 C 7 5 C 9 6 C 5 7 C 4 8 C 12 9 C 6 10 C 3 11 C 2 12 O 1 13 H 19 14 H 18 15 H 16 16 H 15 17 H 17 18 H 14 19 H 13 20 H 20