Reduction
Points to remember in Reduction
PYQ-2024-Periodic_Table_and_Periodicity-Q4, PYQ-2023 Aldehyde and Ketones Q12
(2) $\mathrm{NaBH}_{4}, \mathrm{EtOH}$
PYQ-2024-Aldehydes_and_Ketones-Q1
Aldehyde $\longrightarrow 1^{\circ}$ Alcohol
Ketone $\longrightarrow 2{ }^{\circ} \mathrm{Alcohol}$
Acid halide $\longrightarrow 1^{\circ}$ Alcohol
(3) $\mathrm{Na} / \mathrm{EtOH}$ (Bouveault–Blanc reduction)
Aldehyde $\longrightarrow 1^{\circ}$ Alcohol$\quad$ Ketone $\longrightarrow 2^{\circ}$ Alcohol
Acid halide $\longrightarrow 1^{\circ}$ Alcohol $\quad$ Ester $\longrightarrow$ Alcohol + Alcohol
$RCN \longrightarrow RCH_{2} NH_{2}$
(4) $\mathrm{Na}-\mathrm{Hg} / \mathrm{HCl}$ or
$\mathrm{Al}[\mathrm{OCHMe}]_{3}$ (MPV Reduction)
Aldehyde $\longrightarrow 1^{\circ}$ Alcohol $\quad$ Ketone $\longrightarrow 2^{\circ}$ Alcohol
(5) Rosenmund Reduction
PYQ-2024-Aldehydes_and_Ketones-Q4
(6) Birch reduction
(Li/Na/K + Liquid $\mathrm{NH}_{3}$ )
Note : Terminal alkynes not reduced
(7) Stephen’s Reduction
$R-C \equiv N \xrightarrow[(2) H_{2} O]{(1) SnCl_{2} / HCl} {R}-{CH} = O$
Note : DIBAL-H is also used for same conversion.
(8) Clemmensen Reduction
PYQ-2024-Aldehydes_and_Ketones-Q3, PYQ-2023 Aldehyde and Ketones Q8
Avoid if acid sensitive groups are present in molecule. e.g. $\mathrm{C}=\mathrm{C}, \mathrm{C} \equiv \mathrm{C}, \mathrm{OH}, \mathrm{OR}$,
(9) Wolff-Kishner Reduction
Avoid if base sensitive groups are present in molecule. e.g. COOR, $\mathrm{COX}, \mathrm{CONH}_{n}$,
$-\mathrm{CO}-\mathrm{O}-\mathrm{CO}-\mathrm{R}-\mathrm{X}$
(11) Red Phosphorus and HI
Almost all functional groups containing compounds converts into corresponding alkane by red $\mathrm{P}+\mathrm{HI}$.
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$R-CH_{2} OH \longrightarrow R - CH_{3} $
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$R-CHO \longrightarrow R-CH_{3}$
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$R_{2} CO \longrightarrow R_{2} CH_{2} $ (Alkane)
(12) DIABAL-H reduction
PYQ-2024-Aldehydes_and_Ketones-Q1
$\mathrm{R}-\mathrm{C} \equiv \mathrm{N} \xrightarrow{\mathrm{DIBAL}-\mathrm{H}} \mathrm{R}-\mathrm{CH}=\mathrm{O}$
At ordinary temperature esters reduced to alcohols but at low temperature esters reduced to aldehyde.
Hydrogenation
PYQ-2023 Aldehyde and Ketones Q11
