new index atom name original index 1 C 5 2 C 6 3 C 7 4 C 8 5 C 9 6 C 10 7 C 11 8 C 12 9 O 1 10 O 3 11 O 2 12 O 4 13 H 13 14 H 14 15 H 15 16 H 16 17 H 17 18 H 18 19 H 19 20 H 20 21 H 21 22 H 22 23 H 23 24 H 24 25 H 25 26 H 26