Advertisements
Advertisements
प्रश्न
What is meant by hydroboration-oxidation reaction? Illustrate it with an example.
Illustrate the hydroboration-oxidation reaction with an example.
Advertisements
उत्तर
Diborane (BH3)2 reacts with alkenes to yield trialkylboranes as the addition products. This is oxidised to alcohol by hydrogen peroxide in the presence of aqueous sodium hydroxide.
\[\begin{array}{cc}
\ce{CH3 - CH = CH2 + (H - BH2)2 -> CH3 - CH - CH2 ->[CH3 - CH = CH2] (CH3 - CH2 - CH2)2BH ->[CH3 - CH = CH2] (CH3 - CH2 - CH2)3B ->[[3H2O2, \overset{-}{O}H][H2O] \underset{Propan-1-ol}{3CH3 - CH2 - CH2 - OH} + Bi(OH)3\\
|\phantom{.........}|\phantom{..................................................................................................................................}\\
\ce{H}\phantom{.......}\ce{BH2}\phantom{..............................................................................................................................}\\}
\end{array}\]
The incorporation of borane into the double bond occurs so that the boron atom binds to the sp2 carbon with a higher hydrogen atom count. The resulting alcohol appears to have been produced by the addition of water to the alkene in a manner contrary to Markovnikov’s rule. This process produces alcohol in high yield.
APPEARS IN
संबंधित प्रश्न
Name the reagents used in the following reactions:
How do you convert the following : Propan-2-ol to 2-methylpropan-2-ol
Show how is the following alcohol prepared by the reaction of a suitable Grignard reagent on methanal?
Predict the major product of acid catalysed dehydration of butan-1-ol.
How will you convert: Phenol to 2, 4, 6 − trinitrophenol?
Write the structures of A, B and C in the following reactions :
Primary alcohols are prepared by the reduction of carboxylic acids. Though lithium aluminium hydride is a strong reducing agent, it is not used in the reaction. This is so because:
Monochlorination of toluene in sunlight followed by hydrolysis by aq. \[\ce{NaOH}\] yields.
Benzaldehyde differs from acetaldehyde in that:
Alkenes convert into alcohols by ____________.
Commercially carboxylic acids are reduced to alcohols by converting them to the ______.
The reagent used for dehydration of an alcohol is
The best reagent to convert pent 3 – en 2 – 01 into pent 3 – in – 2 – one is
Glycerol as a trimester present in
To synthesise 1.0 mole of 2-methylpropan-2-ol from Ethylethanoate ______ equivalents of CH3MgBr reagent will be required. (Integer value)
The products "A" and "B" formed in above reactions are:
An aldehyde isomeric with allyl alcohol gives phenyl hydrazone. Pick out a ketone that too gives a phenyl hydrazone containing the same percentage of nitrogen.
\[\ce{C3H8O ->[{[O]}][K2Cr2O7/H2SO4] C3H6O ->[I2 + NaOH(aq.)] CHI3}\]
In this reaction the first compound is:
The major product of the following reaction is:
\[\begin{array}{cc}
\ce{Cl}\phantom{.........................}\\
|\phantom{..........................}\\
\ce{CH3 - CH - CH3 ->[(i) Alc. KOH][(ii) HBr/peroxide (iii) aq. KOH]}
\end{array}\]
