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Direction (Q. Nos. 1 - 8) This section contains 8 multiple choice questions. Each question has four choices (a), (b), (c) and (d), out of which ONLY ONE option is correct.
Q. How many different alkenes are formed when 2 -chlorobutane is treated with ethanolic solution of KOH?
With ethanolic KOH, we have E2 elimination.
So, we have 3 products in all
What is the major dehydration product in the following reaction ?
Note that H2SO4, H3PO4 and KHSO4 are dehydrating agents with rearrangement possible. While P2O5, P4O10, ThO2, POCl3 and Al2O3 are dehydrating agents without any possibility of rearrangement.
Which of the following compounds will lose optical activity after the reaction ?
The correct answer is option B
In which of the following reactions , only single is omer of alkene is formed ?
As there is no hydrogen at adjacent position for E2 elimination.
Consider the following reaction .
The correct statement concerning product of the above reaction is
Both are the same alkene. So only one alkene is formed.
An optically active hydrocarbon X has molecular formula C6H12. X on catalytic hydrogenation gives optically inactive C6H14. X could be
The optically active C6H1 2 hydrocarbon is 3-Methylpent-1-ene, having one chiral carbon shown in fig A.
On catalytic hydrogenation , the compound obtained is shown in fig B, and the molecule does not have chiral carbon.
The reaction is C6H1 2 → C6H1 4 and this reaction takes place inthe presence of H2 and Pd.
Which of the following reactions produces an alkene?
Option a) Diazene(N2H2) is a hydrogenating agent. So, there will be no reaction.
Option b) Al2O3+CrO3 acts as a dehydrogenation catalyst and so an alkene is formed. (Here 1-propene is formed)
Option c) This reaction is Wolff Kishner reaction. Here, acetone would be converted to alkane.
Option d) Zn/CH3COOH substitutes Cl with H and an alkane is formed.
What is the major product of the reaction given below ?
meso -2 ,3 -dichiorobutane + Nal (aq) →
Direction (Q. Nos. 9 -12) This section contains 4 multiple choice questions. Each question has four choices (a), (b), (c) and (d), out of which ONE or MORE THAN ONE are correct.
Q. Which of the following reactions results in the formation of an alkene?
Which of the following reaction(s) produces propene as one of the important organic product?
Consider the following reaction.
The correct statement concerning product alkene(s) is/are
Identify the addition reaction which is not undergone by the alkenes
Alkenes do not undergo mercuration, indeed they undergo oxymercuration , a process in which an alkene is converted into an alcohol.
Direction (Q, Nos. 13 - 16) This section is based on Statement I and Statement II. Select the correct answer from the codes given below.
Statement I : 2-butyne on reduction with Pd/CaCO3 gives c/s-2-butene.
Statement II : Hydrogenation proceed through adsorption mechanism.
A Lindlar catalyst is a heterogeneous catalyst that consists of palladium deposited on calcium carbonate or barium sulphate which is then poisoned with various forms of lead or sulphur. It is used for the hydrogenation of alkynes to cis alkenes (i.e. without further reduction into alkanes) When the triple bond is (2-butyne) hydrogenated over the Lindlar’s catalyst i.e.Pd/CaCO3
it gives predominantly cis alkene(2-butene).
Statement I : 2, 3-dibromo butane with Zn-dust gives frans-2-butene as major product.
Statement II : frans-2-butene is more stable than c/s-2-butene.
Zn reacts with 2,3 - dibromobutane to give alkene. As trans 2-butene is more stable than cis 2-butene(owing tosterric hinderancce), former is major product.
Statement I : 2-bromobutane with (CH3)3COK in tertiary butanol gives 1 -butene as major product.
Statement II : Very strong base (CH3)3COK in tertiary butanol brings about E-2 elimination reaction.
Statement I : Boiling point of an alkene is slightly greater than that of its hydrogenated alkane.
Statement II : Alkenes have stronger van der Waals’ force of attraction than alkanes.
The correct answer is Option D.
The more intermolecular mass is added, the higher the boiling point. Intermolecular forces of alkenes get stronger with increase in the size of the molecules. In each case, the alkene has a boiling point which is a small number of degrees lower than the corresponding alkane.
Direction (Q. Nos. 17 - 20) This section contains 4 questions. When worked o u t wili result in an integer from 0 to 9 (both inclusive).
Q. If 3-bromo-4-methyl hexane is treated with ethanolic KOH solution, how many different alkenes would be formed?
2 is the right answer.
Alcoholic KOH causes dehydrohalogenation reaction i.e. elimination reaction.
If 3-methyl-2-pentanol is heated with concentrated H2SO4 , in principle how many different alkenes result?
methyl 1 pentene
3 methyl 2 butene
2 ethyl 1 butene
Hence 3 is the correct answer.
How many different alkyne isomers upon hydrogenation in the presence of CaCO3 / Pd gives 4-methyl hexene which is simultaneously c/s at double bond?
How many different heptenes result by partial hydrogenation of all possible, unbranched heptynes?
The correct answer is 5.
C=C-C-C-C-C-C , no geometrical isomerism so 1
C-C=C-C-C-C-C 2 , geometrical cis trans
C-C-C=C-C-C-C , cis trans again so 2