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