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