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