number atom shift 6 N 164.556 7 N 129.988 8 N 306.152 9 N 295.448 10 C 63.570 11 C 93.962 12 C 85.851 13 C 80.612 14 C 75.486 15 C 134.397 16 C 162.545 17 C 127.541 18 C 138.446 19 C 127.046 20 H 1.160 21 H 1.227 22 H 0.739 23 H 10.804 24 H 4.855 25 H 4.585 26 H 7.338 27 H 5.364 28 H 4.521 29 H 4.903 30 H 9.233 31 H 8.258