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