Answer
Verified
392.1k+ views
Hint: The dihalide is geminal in nature, as both the halo groups are attached to one carbon atom only. The question will be easy to solve if we go through the mechanism method. Sodium metal extracts acidic hydrogen, $\text{aq}\text{. KOH}$ adds $-\text{OH}$ group replacing halo group, alcoholic $\text{KOH}$ followed by $\text{NaN}{{\text{H}}_{2}}$ are reagents of elimination and zinc removes halo groups only.
Complete answer:
Let us discuss this conversion through its mechanism using a general reaction at first;
If the halogens are attached to the same carbon (geminal) or adjacent carbon atom (vicinal) and it reacts with base, the base extracts the hydrogen atoms and halogen atoms along with it. The general reaction of dihaloalkane elimination is
Let us see the mechanism of this question,
Step (1)- The dihaloalkane is reacted with alcoholic $\text{KOH}$, the halogen attached to it and the hydrogen atom from the adjacent carbon atom will be removed by it as $\text{alc}\text{. KOH}$ is a strong base. The hydrochloric acid is removed and a double appears replacing the atoms. The reaction follows as
Step (2)- The forward is reaction carried out by $\text{NaN}{{\text{H}}_{2}}$ which is very strong base, as it denotes its lone pair and negative charge to incoming electrophiles. The hydrogen atom and chlorine atom present on adjacent carbon atoms are removed by adding one more bond between the two which is $\pi $- bond. The reaction looks like,
The correct answer to this question is ‘b’. Alcoholic $\text{KOH}$ followed by $\text{NaN}{{\text{H}}_{2}}$ reagent is used for the following conversion.
Note:
The moles of bases required to convert dihaloalkanes to terminal (in which triple bond is between ${{\text{C}}_{1}}-{{\text{C}}_{2}}$) alkynes are 3 not 2. The terminal alkynes are acidic in nature, as they readily react with bases to remove acidic hydrogens from them. $\text{RC}\equiv \text{CH}+\text{Base}\to \text{RC}\equiv {{\text{C}}^{-}}\text{bas}{{\text{e}}^{+}}+\dfrac{1}{2}{{\text{H}}_{2}}$. As, one of the base molecules will remove the terminal hydrogen instead of one of the halides.
Complete answer:
Let us discuss this conversion through its mechanism using a general reaction at first;
If the halogens are attached to the same carbon (geminal) or adjacent carbon atom (vicinal) and it reacts with base, the base extracts the hydrogen atoms and halogen atoms along with it. The general reaction of dihaloalkane elimination is
Let us see the mechanism of this question,
Step (1)- The dihaloalkane is reacted with alcoholic $\text{KOH}$, the halogen attached to it and the hydrogen atom from the adjacent carbon atom will be removed by it as $\text{alc}\text{. KOH}$ is a strong base. The hydrochloric acid is removed and a double appears replacing the atoms. The reaction follows as
Step (2)- The forward is reaction carried out by $\text{NaN}{{\text{H}}_{2}}$ which is very strong base, as it denotes its lone pair and negative charge to incoming electrophiles. The hydrogen atom and chlorine atom present on adjacent carbon atoms are removed by adding one more bond between the two which is $\pi $- bond. The reaction looks like,
The correct answer to this question is ‘b’. Alcoholic $\text{KOH}$ followed by $\text{NaN}{{\text{H}}_{2}}$ reagent is used for the following conversion.
Note:
The moles of bases required to convert dihaloalkanes to terminal (in which triple bond is between ${{\text{C}}_{1}}-{{\text{C}}_{2}}$) alkynes are 3 not 2. The terminal alkynes are acidic in nature, as they readily react with bases to remove acidic hydrogens from them. $\text{RC}\equiv \text{CH}+\text{Base}\to \text{RC}\equiv {{\text{C}}^{-}}\text{bas}{{\text{e}}^{+}}+\dfrac{1}{2}{{\text{H}}_{2}}$. As, one of the base molecules will remove the terminal hydrogen instead of one of the halides.
Recently Updated Pages
Basicity of sulphurous acid and sulphuric acid are
Three beakers labelled as A B and C each containing 25 mL of water were taken A small amount of NaOH anhydrous CuSO4 and NaCl were added to the beakers A B and C respectively It was observed that there was an increase in the temperature of the solutions contained in beakers A and B whereas in case of beaker C the temperature of the solution falls Which one of the following statements isarecorrect i In beakers A and B exothermic process has occurred ii In beakers A and B endothermic process has occurred iii In beaker C exothermic process has occurred iv In beaker C endothermic process has occurred
What is the stopping potential when the metal with class 12 physics JEE_Main
The momentum of a photon is 2 times 10 16gm cmsec Its class 12 physics JEE_Main
How do you arrange NH4 + BF3 H2O C2H2 in increasing class 11 chemistry CBSE
Is H mCT and q mCT the same thing If so which is more class 11 chemistry CBSE
Trending doubts
Assertion CNG is a better fuel than petrol Reason It class 11 chemistry CBSE
How does pressure exerted by solid and a fluid differ class 8 physics CBSE
Number of valence electrons in Chlorine ion are a 16 class 11 chemistry CBSE
What are agricultural practices? Define
What does CNG stand for and why is it considered to class 10 chemistry CBSE
The rate of evaporation depends on a Surface area b class 9 chemistry CBSE
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
State whether the following statement is true or false class 11 physics CBSE
A night bird owl can see very well in the night but class 12 physics CBSE