Question

The mass spectrum ofcompound A shows the molecularon at m: ss, an M I peak at m: 86 of appror mately 6% abundance relatrie to M and an M 2 peak atm:37 of ess an 19, a un ance relati e o M Assuming that compound A has only C, H, and one N atoms, determine the molecular formula, and then draw a possible structure if compound A has IR absorption at 1620-1680 cm1 but not at 3010-3090 cm You do not have to consider stereochemistry . You do not have to explicitly draw H atoms. If more than one structure fits the description, draw them all .Separate structures with+signs from the drop-down menu. ChemDoodle

Answer 1

To determine the molecular formula of compound A, we will follow these steps:

1. Identify the molecular ion (M) peak: m/z 85 (since "m: ss" is likely a typo and should be "m: 85")
2. Identify the presence of nitrogen: M+1 peak at m/z 86 with 6% abundance relative to M, suggests the presence of one nitrogen atom (N).
3. Calculate the number of carbon atoms: M+2 peak at m/z 87 with 10% abundance relative to M, suggests the presence of 10/1.1 ≈ 9 carbon atoms (C).

Now, we can determine the molecular formula of compound A:
C9HxN, where x is the number of hydrogen atoms.

To find the number of hydrogen atoms, we will use the molecular ion mass:
85 = 9(12.01) + x(1.01) + 14.01
85 = 108.09 + x(1.01)
x ≈ 13

So, the molecular formula of compound A is C9H13N.

Now, let's consider the IR absorption information:
- Absorption at 1620-1680 cm-1 indicates a C=C double bond (alkene) or C=N bond.
- No absorption at 3010-3090 cm-1 suggests the absence of an alkene with sp2 hybridized C-H.

Possible structure(s) for compound A can be drawn by considering a C=C double bond or a C=N bond with the given molecular formula C9H13N. One possible structure is N-ethyl-3-methyl-2-butene:

CH3-CH2-CH=CH-CH(CH3)-NH-CH2-CH3

Remember that other structures may also fit the description, but this is one example.