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