new index atom name original index 1 C 9 2 C 10 3 C 6 4 C 7 5 C 8 6 C 11 7 C 4 8 C 5 9 C 12 10 O 1 11 O 2 12 O 3 13 H 16 14 H 17 15 H 13 16 H 14 17 H 15 18 H 18 19 H 19 20 H 20