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