Question

An alkene 'A' contains three C–C, eight C–H σ–bonds, one C–C π –bond. 'A' on ozonolysis gives two moles of an aldehyde of molar mass 44 u. Write the IUPAC name of 'A'.

Answer 1

The data given in the question is that 'A' on ozonolysis yields 2 moles of an aldehyde.  As there are two moles of aldehyde being formed, it denotes that on both sides of the double bond having carbon atoms, there exists identical structural units. This is represented as  

XC=CX

But we also know that the molar mass of the aldehyde is 44 u. So, it should be ethanal

$C{ H }_{ 3 }CH\quad =\quad 0$

Now, we need to write two moles of ethanal next to each other such that their oxygen atoms point each other.

$\begin{matrix} C{ H }_{ 3 }CH \\ Ethanal \end{matrix}\begin{matrix} =\quad O\quad O\quad = \\ \quad \end{matrix}\begin{matrix} CHC{ H }_{ 3 } \\ Ethanal \end{matrix}$

If we "remove the oxygen" atoms and join the two moles of ethanal by a double bond, we will get the "structure of alkene" 'A' containing 3 C-C, 8 C-H σ-bonds and 1 C-C π -bond.

$C{ H }_{ 3 }\quad -\quad CH\quad =\quad CH\quad -\quad C{ H }_{ 3 }$

The IUPAC Name of 'A' is But-2-ene.