Question

Question 044 Which of the following sequences converts 2-methylpropene and sodium acetylide into 3-methylbutanal? 1) HBr; 2) NaCCH; 3) O3; 4) DMS 1) NaCCH; 2) H2/Ni2B; 3) O3; 4) DMS 1) HBr, ROOR; 2) NaCCH; 3) H2/Ni2B 4) O3; 5) DMS 1) HBr, ROOR; 2) NaCCH; 3) O3; 4) H2O 1) HBr; 2) NaCCH; 3) O3; 4) H2O

Answer 1

Answer:

1) HBr; 2) NaCCH; 3) O3; 4) H2O

Explanation:

The first step is formation of alkyl halide followed by reaction with sodium acetylide, to form 3-methylbutene, which is then followed by oxidation reaction with O3& H2O to 3-methylbutanal

Answer 2

Answer:

The sequence of reagents' incorporation for the conversion of 2-methylpropene into 3-methylbutanal is option (C.):

1. $HBr,ROOR$ ; 2.  $NaCCH,H_{2}/Ni_{2}B$ ; 3. $O_{3}, DMS$

Explanation:

The summary of this reaction's mechanism is as follows:

• Radical hydro-halogenation of 2-methylpropene through a technique known as "peroxide effect" in which the HBr addition causes free radical formation of the alkene
• Nucleophilic SN2 substitution reaction (acetylide)
• Hydrogenation
• Ozonolysis of the alkene: after the addition reaction, the intermediate ozonide is converted to aldehyde using dimethyl sulfide (DMS)