Question

1. Diazepam, has 3 rings, 8 double bonds, and the formula C₁₆H_?ClN₂O. How many hydrogens does Diazepam have? (Calculate the answer, don't count)

I know that 3 rings = 3 Du and 8 double = 1Du, thus there is 11 Du

I'm confused on what to do next, the book has C₁₆H₃₄-H₂₂= C₁₆H₁₂ ----->answer is C₁₆H₁₃ClN₂O

How do you use the 11Du to calculate the number of Hydrogens?

Answer 1

Degree of unsaturation is the number of rings and number of double bonds present in molecule.

So Diazepam has 3 rings and 8 double bonds.

3+8 = 11 =>Du

we know that,

Du = (2C+2) - H + N -Cl / 2

Here

Number of Carbon is 15

Number of Nitrogen is 2

Number of Chlorine is 1

substitute these numbers in the above equation

Du = ((2 x 16 + 2) - H + 2 -1) / 2

Du = (34 - H + 2 -1)/2

Du = 35 - H /2

we know that Du = 11

So,

35 - H /2 = 11

-H = 22 - 35

H = 13

So the number of Hydrogen is 13

Hence the answer is C₁₆H₁₃ClN₂O