A terminal alkyne X undergoes partial reduction in the presence of H₂ and Lindlar's catalyst to form an alkene Y . When Y is subjected to reductive ozonolysis, it produces a mixture of two aldehydes. If one of the aldehydes is formaldehyde and the other has a molar mass of 58 g mol ⁻¹ , identify the starting alkyne X .

Step-by-step solution

The aldehyde with a molar mass of 58 g mol ⁻¹ has the general formula C_nH_ 2n O . 12n + 2n + 16 = 58 14n = 42 n = 3 Thus, the aldehyde is propanal ( CH₃CH₂CHO ). The products of the reductive ozonolysis of alkene Y are formaldehyde ( HCHO ) and propanal ( CH₃CH₂CHO ). Reconstructing the alkene Y by removing the oxygen atoms and joining the carbonyl carbons with a double bond gives but-1-ene ( CH₃CH₂CH=CH₂ ). Since Y was formed by the partial reduction of a terminal alkyne X , the starting alkyne must be but-1-yne