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