InterviewSolution
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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Ethyl acetoacetate when reacts with one mole methyl magnesium iodide then product of reaction will be :A. `CH_(3)-overset(O)overset(||)(C)-CH_(2)-overset(O)overset(||)(C)-CH_(3)`B. `CH_(3)-underset(CH_(3))underset(|)overset(O^(Θ)Mg^(o+)Br)overset(|)(C)-CH_(2)-overset(O)overset(||)(C)-CH_(3)`C. `CH_(3)-overset(O)overset(||)(C)-underset(overset(o+)(MgBr))overset(Θ)(CH)-CO_(2)Et`D. `CH_(2)^(-)overset(O)overset(||)(C)-CH_(2)-CO_(2)Et` |
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Answer» Correct Answer - C `CH_(3)-overset(O)overset(||)(C)-CH_(2)-overset(O)overset(||)(C)-O-Et overset(CH_(3)MgBr)rarrCH_(3)-overset(O)overset(||)(C)-underset(overset(o+)(MgBr))overset(Θ)(CH)-CO_(2)Et` (because of active methylene group acid-base take place). |
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| 2. |
How many isomer of `C_(4)H_(10)O` reacts with `CH_(3)MgBr` to evolve `CH_(4)` gas ? (Excluding stereoisomer) |
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Answer» Correct Answer - 4 (a) `C-C-C-C-OH` , (b) `C-C-overset(OH)overset(|)(C)-C` (c) `C-overset(C)overset(|)(C)-C-OH` , (d) `C-underset(OH)underset(|)overset(C)overset(|)(C)-C` All these alcohol have active hydrogen so these are capable to reacts with `CH_(3)MgBr` to evolve `CH_(4)` gas. |
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| 3. |
Match The coloumn I and II. (Matrix) |
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Answer» Correct Answer - a-r; b-q; c-p; d-s Reaction of Grignard reagent with aldehyde or ketone is an example of nucleophilic addition. |
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| 4. |
Match The coloumn I and II. (Matrix) Match the missing reactant A, B, C, D |
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Answer» Correct Answer - a-s; b-r; c-q; d-p Reaction of Grignard reagent with aldehyde or ketone is an example of nucleophilic addition. |
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| 5. |
Ethylmercaptan is prepared by the reaction of the following, followed by hydrolysis :A. `C_2 H_5 MgBr + SO_2`B. `C_2 H_5 Mg Br + S`C. `C_2 H_5 MgBr + CS_2`D. `C_2 H_5 Mg Br + H_2 S`. |
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Answer» Correct Answer - B (b) `C_2 H_5 Mg Br + S underset (H_3 O^(oplus))rarr C_2 H_5- SH`. |
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| 6. |
Reactivity of with the following `G.R` in the decreasing order is : (i) `MeMgBr` (ii) `EtMgBr` (iii) `Me_2 CH-MgBr` (iv) `Me_3 C - MgBr`.A. `(i) gt (ii) gt (iii) gt (iv)`B. `(iv) gt (iii) gt (ii) gt (i)`C. `(i) gt (ii) gt (iv) gt (iii)`D. `(iv) gt (ii) gt (iii) gt (i)` |
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Answer» Correct Answer - A (a) Since the `G.R` reacts by `SN^2` mechanism, the reactivity order of `SN^2` reaction is `1^@ RMgX gt 2^@ RMgX gt 3^@ RMgX`. Hence, the answer is `(a)`. |
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| 7. |
Propane is not formed when `C_3 H_7 MgBr` is treated withA. `H_2`B. PhenolC. Ethanoic acidD. 2-Butyne |
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Answer» Correct Answer - D (d) `H-H,PhOH,` and `Me-COOH` contain active `H` atom. `C_3 H_7 MgBr` reacts with them to give propane gas. Butyne-2(`Me - -= - Me`) does not have active `H` atom and hence does not react with `G.R`. |
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| 8. |
Grignard reagent is usually prepared by `R-X+Mg overset(Et_(2)O)rarrRMgX " " "Grignard reagent"` `Ar-X+Mg overset(Et_(2)O)rarrArMgX " " "Grignard reagent"` Grignard reagent acts s a strong base. Grignard reagent carry out nucleoplilic attack in absence of acidic hydrogen. Grignard reagent form complex with its ether solvent. Complex formation with molecule of ether is an important factor in the formation and stability of Grignard reagent. Which of the following will undergo acid-base reaction with Grignard reagent ?A. `HC-=CH`B. `R-OH`C. `R-CO_(2)H`D. All of these |
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Answer» Correct Answer - D Grignard reagents are usually prepared by the reaction by the reaction of an organic halide and magnesium metal (turnings) in an ether solvent. `{:(RX+Mg overset(Et_(2)O)rarrRMgX),(ArX+Mg overset(Et_(2)O)rarrArMgX):}} "Grignard reagents"` The order of reactivity of halides with magnesium is also `RI gt RBr gt RCl`. Very few organomagnesium fluorides have been prepared. aryl Grignard reagents are more easily prepared from aryl bromides and aryl iodides than from aryl chlorides, which react very sluggishly. Grignard reagents are seldom isolated but are used for further reactions in ether solution. The ether solution can be analyzed for the content of the Grignard reagent, however, and the yields of Grignard reagents are almost always very high (85-95%). Two examples are shown here: `CH_(3)I+Mg underset(35^(@)C)overset(Et_(2)O)rarr underset((95%))underset("Methylmagnesium iodide")(CH_(3)MgI)` `C_(6)H_(5)Br+Mgunderset(35^(@)C)overset(Et_(2)O)rarr underset((95%))underset("Phenylmagnesium bromide")(C_(6)H_(5)MgBr)` |
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| 9. |
Compound A was treated with a large excess of `CH_(3)MgBr`. The resulting products was exposed to `POCl_(3)`/pyridine to give compound B, as one of many products: Which of the following compounds cab be A ?B. C. D. |
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Answer» Correct Answer - D `POCl_(3)`/Pyridine is dehydrating agent. It will cause elimination of `H_(2)O` to give alkene. |
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| 10. |
Total number of RMgX are consumed in the following reaction |
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Answer» Correct Answer - 7 Esters and nitrite will consume 2 moles RMgX each. Ketone will consume only one mole. |
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| 11. |
What sequence of steps represents the best best synthesis of 4-heptanol `(CH_(3)CH_(2)CH_(2))_(2) CHOH` ?A. `CH_(3)CH_(2)CH_(2)MgBr` (2 moles) + formaldehyde `(H_(2)C=O)` in diethyl ether followed by `H_(3)O^(+)`B. `CH_(3)CH_(2)CH_(2)MgBr +` butanol `(CH_(3)CH_(2)CH_(2)CH=O)` in diethyl ether followed by `H_(3)O^(+)`C. `CH_(3)CH_(2)CH_(2)CH_(2)MgBr+` acetone `[(CH_(3))_(2)C=O]` in diethyl ether followed by `H_(3)O^(+)`D. `(CH_(3)CH_(2)CH_(2))_(2)CHMgBr+` formaldehyde `(H_(2)C=O)` in diethyl ether followed by `H_(3)O^(+)` |
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Answer» Correct Answer - B (a) Gives 1-Butanol as the product (c) Gives 2-methyl-2-hexanol as the product (d) Gives 2-propyl-1-pentanol as the product only (b) gives 4-heptanol as the product. |
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| 12. |
What is the ratio of (x/y) in above problem ?A. `1.5`B. 2C. `2.5`D. 3 |
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Answer» Correct Answer - B Reaction (1) x = 6 2 mole of `CH_(3)MgBr` act as a base 4 mole of `CH_(3)MgBr` act as a nucleophile Reaction (2) y = 3 3 mole of `CH_(3)MgBr` act as a nucleophile. |
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| 13. |
For the sequence of reactions, `Aunderset("ether")overset(C_(2)H_(5)MgI)rarrBoverset(H_(2)O //H^(+))rarr` tert-Pentyl alcohol. The compound A in the sequence is :A. 2-ButanoneB. AcetaldehydeC. AcetoneD. Propanal |
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Answer» Correct Answer - C `CH_(3)-underset((A))overset(O)overset(||)(C)-CH_(3)overset(EtMgI//"ether")rarrCH_(3)-underset(Et)underset(|)overset(OMgI)overset(|)(C)-CH_(3)overset(H_(3)O^(o+))rarrCH_(3)-underset(3^(@) "pentyl alcohol")(underset(CH_(2)-CH_(3))underset(|)overset(OH)overset(|)C-CH_(3))` |
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| 14. |
In which of the following reaction `2^(@)` alcohol is obtained as a product ?A. B. C. D. Both (a) and (b) |
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Answer» Correct Answer - D (a), (b) are example of nucleophilic addition reaction of GR on aldehyde while in (c) GR adds on ketone. |
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| 15. |
Grignard reagent is usually prepared by `R-X+Mg overset(Et_(2)O)rarrRMgX " " "Grignard reagent"` `Ar-X+Mg overset(Et_(2)O)rarrArMgX " " "Grignard reagent"` Grignard reagent acts s a strong base. Grignard reagent carry out nucleoplilic attack in absence of acidic hydrogen. Grignard reagent form complex with its ether solvent. Complex formation with molecule of ether is an important factor in the formation and stability of Grignard reagent. Which of the following reactants give primary alcohol as a major product when reacts with RMgX followed by acidification? A. I, ii, vB. I, ii, v, viC. ii, iv, viD. v, vi, iii, vi |
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Answer» Correct Answer - A Grignard reagents are usually prepared by the reaction by the reaction of an organic halide and magnesium metal (turnings) in an ether solvent. `{:(RX+Mg overset(Et_(2)O)rarrRMgX),(ArX+Mg overset(Et_(2)O)rarrArMgX):}} "Grignard reagents"` The order of reactivity of halides with magnesium is also `RI gt RBr gt RCl`. Very few organomagnesium fluorides have been prepared. aryl Grignard reagents are more easily prepared from aryl bromides and aryl iodides than from aryl chlorides, which react very sluggishly. Grignard reagents are seldom isolated but are used for further reactions in ether solution. The ether solution can be analyzed for the content of the Grignard reagent, however, and the yields of Grignard reagents are almost always very high (85-95%). Two examples are shown here: `CH_(3)I+Mg underset(35^(@)C)overset(Et_(2)O)rarr underset((95%))underset("Methylmagnesium iodide")(CH_(3)MgI)` `C_(6)H_(5)Br+Mgunderset(35^(@)C)overset(Et_(2)O)rarr underset((95%))underset("Phenylmagnesium bromide")(C_(6)H_(5)MgBr)` |
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| 16. |
Which of the following alcohol can not be prepared by the reaction of acid chloride with excess of Grignard reagent followed by acidification ?A. B. C. D. |
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Answer» Correct Answer - D `R-overset(O)overset(||)(C)-Cl+R_(1)MgBr underset((2)H^(o+))rarr R-underset(R_(1))underset(|)overset(OH)overset(|)(C)-R_(1)` at least two like group are attached with `3^(@)` alcohol then that alcohol can be prepared. (d) has three unlike group : it cannot be prepared. |
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| 17. |
The structure of product `(B)` is :A. B. C. D. |
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Answer» Correct Answer - C ( c) The order of reactivity of `G.R` with different compounds is Alcohol gt Aldehyde gt Ketone gt `R - overset(O)overset(||)(C )-X` gt Ester gt Anhydride gt Arnide gt -`CH_2 X`. So the first mole of `G.R` will react with alcohols. `(ROH + RMgX rarr RH + ROMgX)`, Hence, answer is `( c)`. |
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| 18. |
The structure of product `(C)` is :A. B. C. D. |
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Answer» Correct Answer - A (a) The second mole of `G.R` will react will aldehyde to give a magnesium bromide derivative of `2^@` alcohol since hydrolysis is not carried out. One `R` group (i.e., `Ph` group group) comes from `G.R` Hence, the answer is `(a)`. |
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| 19. |
The structure of product `(D)` is :A. B. C. D. |
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Answer» Correct Answer - B (b) The third mole of `G.R` will react with ketone to give a magnesium bromide derivative of `3^@` alcohol. One `R` group (i.e., `Ph` group) comes from `G.R`. Hence, the answer is `(b)`. |
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| 20. |
The structure of product `(E)` is :A. B. C. D. |
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Answer» Correct Answer - B (b) On hydrolysis, `ROMgX` gives `ROH`. Magnesium bromide derivatives of `2^@` and `3^@` alcohols give `2^@` and `3^@` alcohols, respectively, leaving amide group as such. Hence, the answer is `(b)`. |
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| 21. |
The structure of product `(C)` is :A. B. C. D. |
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Answer» Correct Answer - A (a) The product `( C)` is same as `(A)`. Hence, the answer is `(a)`. |
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| 22. |
In the following reaction sequence, the products `(B)` to `( E)` are formed. . The structure of product `( C)` is :A. B. C. D. |
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Answer» Correct Answer - D (d) `HBr` converts `(-CH_2 OH)` group to `(-CH_2 Br)` group. Hence, the answer is `(d)`. |
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| 23. |
In the following reaction sequence, the products `(B)` to `( E)` are formed. . The structure of product `(B)` is :A. B. C. D. |
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Answer» Correct Answer - C ( c) `LiAlH_4` reduces `(C -= C)` to `(C = C)` bond in anti manner to give trans-alkene and also reduces `(CHO)` group to `(-CH_2OH)` group. Hence, the answer is `( c)`. |
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| 24. |
Which of the following would give benzene when reacted with `PhMgBr` ?A. B. `H_(2)`C. Methyl amineD. `NH_(3)` |
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Answer» Correct Answer - A::B::C::D (a,b,c,d) All of them contain active `H` atom and give benzene with `PhMgBr`. |
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| 25. |
A student was carrying out a Grignard reaction between PhMgBr and ethyl benzoate. She ran out of anhydrous ether just after the Grignard reagent was made. Which of the following solvents can still be used to dissolve the ethyl benzoate for its reaction with already formed PhMgBr ?A. acetoneB. ethyl acetoneC. absolute alcoholD. benzene |
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Answer» Correct Answer - D Benzene will not react with Grignard reagent. |
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| 26. |
`underset(" "CH_(2)-SH)underset(|)overset(" "CH_(2)-OH)overset(|)(" "CH-OH)+underset("(Execess)")(CH_(3)MgBr)rarrx CH_(4)` What is the value of x in the above reaction ?A. 1B. 2C. 3D. 4 |
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Answer» Correct Answer - C Because 3 acidic H are present. |
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