In: Chemistry
Indicate how you would carry out each of the following reactions. How would you distinguish between the starting material and product by IR? Your answer should include both disappearance as well as appearance of IR absorptions.
A) 1-methylcyclohexene to trans-2-methylcyclohexanol
B) cyclohexene to cis-1,2-cyclohexandiol
C) 1-hexyne to 2-hexanone
D) 1-hexyne to 1-hexene
E) 3-chloropentane to 2-pentene
Answer – Given, A) 1-methylcyclohexene to trans-2-methylcyclohexanol-
We know in the 1-methylcyclohexene there is major showing IR peak around the 1600 to 1680 cm-1 and it gets disappeared in the trans-2-methylcyclohexanol and there is another major peak showing at 3200-3600 cm-1 which is board. So the IR peak for alkene gets disappeared in the product and formed new for the alcohol.
B) cyclohexene to cis-1,2-cyclohexandiol – In this one there is major showing IR peak around the 1600 to 1680 cm-1 for C=C and it gets disappeared in the cis-1,2-cyclohexandiol. In the cis-1,2-cyclohexandiol there is major peak for –OH, means for alcohol and due to H-bonding it is showing broad peak around 3200-3600 cm-1. So in this one also the IR peak for alkene gets disappeared in the product and formed new for the alcohol.
C) 1-hexyne to 2-hexanone – In this one there is major IR peak show for the alkyne in the reactant 1-hexyne we know alkyne show around 2100-2260 cm-1 for C triple bond C which is gets disappeared in the 2-hexanone. In the 2-hexanone there is major IR peak show at 1705-1725 cm-1for carbonyl group. So in this one there alkyne IR peak gets disappeared and new 1705-1725 cm-1 is formed.
D) 1-hexyne to 1-hexene – In this one there is major IR peak show for the alkyne in the reactant 1-hexyne we know alkyne show around 2100-2260 cm-1 for C triple bond C which is gets disappeared in the 1-hexene and thee is show new IR peak around 1600 to 1680 cm-1 for C=C. So there is IR peak for alkyne gets disappeared and for alkene gets formed.
E) 3-chloropentane to 2-pentene – In this one major peak show around 600-800 cm-1 for the C-Cl stretching and it gets disappeared in the 2-pentene. In the 2-pentene there is show a new IR peak at 1600 to 1680 cm-1 for C=C. So in this one there is alkyal halide converted to alkene.