new index atom name original index 1 C 11 2 C 8 3 C 9 4 C 6 5 C 7 6 C 3 7 C 5 8 C 4 9 C 10 10 O 1 11 O 2 12 H 20 13 H 18 14 H 19 15 H 16 16 H 17 17 H 12 18 H 13 19 H 14 20 H 15 21 H 21