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