Why are Grignard reagents soluble in ether but not in benzene ?

Why are Grignard reagents soluble in ether but not in benzene ? 
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1 Answer

Answer :

Ans. Grignard reagents from co-ordination complexes with ether but not benzene since the former has lone pair of electrons but the later does not.
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Di-tert butyl ether cannot be made by Williamson’s synthesis. Explain why ?

Description : Di-tert butyl ether cannot be made by Williamson’s synthesis. Explain why ?

Last Answer : Ans. To prepare di tert-butyl ether by Williamson's synthesis, we need tert-butyl bromide and Sodium tertiary butoxide. Since tert-butyl bromide being 3°-alkyl halide prefers to ... rather than substitution, therefore the product obtained is isobutylene rather than ditertiary butyl ether.

How an — OH group attached to carbon in the benzene ring activates benzene towards electrophilic substitution ?

Description : How an — OH group attached to carbon in the benzene ring activates benzene towards electrophilic substitution ?

Last Answer : The lone pair of electrons present on oxygen atom enter into resonance with the benzene ring. As a result, the electron density becomes higher at o- and p- position and due to higher electron density, the ring gets activated towards electrophilic substitution.

Ortho and paranitrophenols are more acidic than phanel. Draw the resonance structures of the corresponding phonoxide ion.

Description : Ortho and paranitrophenols are more acidic than phanel. Draw the resonance structures of the corresponding phonoxide ion.

Last Answer : Ans:- Electronwithdrawal by nitro group makes the plenoxide ion more resonance stabilized and so the strength of phenel increases.

Why phenol is acidic ?

Description : Why phenol is acidic ?

Last Answer :  Ans: In phenol dissociation takes place as follows.   The conjugate base of phenol ie. Phenoxide ion is resonance stabilized. This is why the negative charge on oxygen atom is ... ion has less tendency to form undissociated phenol molecule and equilibrium lies towards right direction.  

Why is it that secondary alcohols can only undergo a single oxidation step in contrast to primary alcohols?

Description : Why is it that secondary alcohols can only undergo a single oxidation step in contrast to primary alcohols?

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Alcohols acts as weak bases. Explain.

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Last Answer : The oxygen atom of the hydroxyl group has two lone pairs of electrons. Therefore alcohols accept a proton from strong mineral acid to form oxonium ions. Hence act as weak bases.

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Ethers are cleaved by acids not by based. Why ?

Description : Ethers are cleaved by acids not by based. Why ? 

Last Answer : The C - O - C bond in ethers like the C - OH bond in alcohols is quite strong. In order to weaken it, the oxygen atom must be protonated. A subsequent nucleophile attack by a strong ... protonation of O atom of ether and therefore only acids can bring about the cleavage of ethers and not bases.

While separating a mixture of ortho and para-nitro phenols by steam distillation, name the isomer which will be steam volatile. Give reasons.

Description : While separating a mixture of ortho and para-nitro phenols by steam distillation, name the isomer which will be steam volatile. Give reasons.

Last Answer : In o-nitrophenol, there is intramolecular hydrogen bonding as follows : In p-nitrophenol, there is intramolecular hydrogen bonding as follows :   Due to intermolecular H ... -nitrophenol. Hence o-nitraphenol due to its lower b. p. is steam volatile while pnitrophenol is not.

Alcohols are easily protonated than phenols. Justify.

Description : Alcohols are easily protonated than phenols. Justify.

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Name the products obtained when anisole is treated with HI.

Description : Name the products obtained when anisole is treated with HI.

Last Answer : Ans. Phenol and methyl iodide. 

Phenol has smaller dipole moment than methanol. (OR) Why are dipole moments of phenols smaller than dipole moments of alcohols ?

Description : Phenol has smaller dipole moment than methanol. (OR) Why are dipole moments of phenols smaller than dipole moments of alcohols ?

Last Answer : Due to electron-withdrawing effect of the benzene ring, the C — O bond in phenol is less polar but in case of methanol due to electron-donating effect of — CH3 group, C — O bond is more polar.

What is usually added to ethyl alcohol to make it unfit for drinking purposes ?

Description : What is usually added to ethyl alcohol to make it unfit for drinking purposes ?

Last Answer : Ans. Methanol and Pyridine. 

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Description : What is the main product obtained when vapours of t-butyl alcohol are passed over copper at 300° ?

Last Answer : Ans. Isobutylene (2-Methyl propene) 

Explain why Grignard reagents do not reacts with alkanes.

Description : Explain why Grignard reagents do not reacts with alkanes.

Last Answer : Ans. In alkanes , the C – H bond has very little polarity . The hydrogen cannot be abstracted by the Grignard reagent.

Which of the following reagents will react readily with both aldehydes and ketones? (a) Grignard reagent (b) Fehling's reagent (c) Tollens' reagent (d) Schiff's reagen

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Last Answer : Grignard reagent

Ketones react with Grignard reagents to form an addition product which on hydrolysis gives a (a) Primary alcohol (b) Tertiary alcohol (c) Secondary alcohol (d) Ketal

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Last Answer : Tertiary alcohol

Grignard reagents do not show any reaction with (a) Alkoxyalkanes (b) Alkanones (c) Alkyl alkanoates (d) Acyl halides

Description : Grignard reagents do not show any reaction with (a) Alkoxyalkanes (b) Alkanones (c) Alkyl alkanoates (d) Acyl halides

Last Answer : Alkoxyalkanes

Which of the following reagents readily react with ethyl methyl ether? (a) NaOH (b) Conc HI (c) KMnO4 (d) H2O

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Which of the reactions between the following pairs of reagents proceeds by a mechanism that may be described as an electrophilic substitution? (a) Benzene + Br2/FeBr3 (b) Propene + Br2 (c) Acetone + NH2NH2 (d) Ethyl bromide + aq KOH

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Last Answer : Benzene + Br2/FeBr3

Which of the following reagents is most suitable for preparing chlorobenzene from benzene? (a) Aqueous chlorine (b) Chlorine in the presence of ultraviolet light (c) Chlorine in acetic acid (d) Chlorine in the presence of FeCl3

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Last Answer : Chlorine in the presence of FeCl3

Which of the following pairs of reagents will not form ether

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Nail polish remover contains? (1) Benzene (2) acetic acid (3) acetone (4) petroleum ether

Description : Nail polish remover contains? (1) Benzene (2) acetic acid (3) acetone (4) petroleum ether

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White phosphorus is always kept under (1) benzene (2) kerosene (3) ether (4) water

Description : White phosphorus is always kept under (1) benzene (2) kerosene (3) ether (4) water

Last Answer : (4) water Explanation: White phosphorus is a material made from a common allotrope of the chemical element phosphorus that is used in smoke, tracer, illumination and incendiary munitions. Other common names include WP ... on fire, and cause serious burns or death and that is why it is kept in water.

White phosphorus is always kept under (1) benzene (2) kerosene (3) ether (4) water

Description : White phosphorus is always kept under (1) benzene (2) kerosene (3) ether (4) water

Last Answer : water

Nail polish remover contains------? A. Acetone (Answer) B. Benzene C. Acetic acid D. Petroleum ether

Description : Nail polish remover contains------? A. Acetone (Answer) B. Benzene C. Acetic acid D. Petroleum ether

Last Answer : A. Acetone (Answer)

The compound that on treatment with benzene sulphonyl chloride, forms a precipitate soluble in alkali, is

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Lecithins are soluble in ordinary solvents except (A) Benzene (B) Ethyl alcohol (C) Methyl alcohol (D) Acetone

Description : Lecithins are soluble in ordinary solvents except (A) Benzene (B) Ethyl alcohol (C) Methyl alcohol (D) Acetone

Last Answer : Answer : D

Proteins are soluble in (A) Anhydrous acetone(B) Aqueous alcohol (C) Anhydrous alcohol (D) Benzene

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Last Answer : Answer : B

What is Grignard reagent?

Description : What is Grignard reagent?

Last Answer : Ans. Alkyl magnesium halides

Which reaction does not yield an ester as one of the products?(a) A carboxylic acid is heated with an alcohol (b) A Grignard reagent is added to a carboxylic acid (c) An acid halide is treated with an alcohol (d) An alkyl halide is heated with the salt of a carboxylic acid

Description : Which reaction does not yield an ester as one of the products? (a) A carboxylic acid is heated with an alcohol (b) A Grignard reagent is added to a carboxylic acid (c) An acid halide is treated with an alcohol (d) An alkyl halide is heated with the salt of a carboxylic acid

Last Answer : A Grignard reagent is added to a carboxylic acid

Which of the following alcohols can be prepared by the reaction of methyl formate with excess Grignard reagent? (a) 1-pentanol (b) 2-pentanol (c) 3-pentanol (d) 2-methyl-2-pentanol

Description : Which of the following alcohols can be prepared by the reaction of methyl formate with excess Grignard reagent? (a) 1-pentanol (b) 2-pentanol (c) 3-pentanol (d) 2-methyl-2-pentanol

Last Answer : 3-pentanol

Which of the following is correct? (a) When a Grignard reagent reacts with a ketone, the addition product is a primary alcohol. (b) When a Grignard reagent reacts with a ketone, the addition product is a secondaryalcoho(c) When a Grignard reagent reacts with a aldehyde, the addition product is a tertiary alcohol. (d) None of the above are correct.l

Description : Which of the following is correct? (a) When a Grignard reagent reacts with a ketone, the addition product is a primary alcohol. (b) When a Grignard reagent reacts with a ketone, the addition product ... with a aldehyde, the addition product is a tertiary alcohol. (d) None of the above are correct.

Last Answer : None of the above are correct.

The disappearance of the purple color of KMnO4 in its reaction with alkene is known as (a) Markovnikov test (b) Grignard test (c) Baeyer test (d) Wurtz test

Description : The disappearance of the purple color of KMnO4 in its reaction with alkene is known as (a) Markovnikov test (b) Grignard test (c) Baeyer test (d) Wurtz test

Last Answer : Baeyer test

Whose name is given to alkylmagnesium halides: w) Victor Grignard x) Daniel Rutherford y) Dmitri Mendeleev

Description : Whose name is given to alkylmagnesium halides: w) Victor Grignard x) Daniel Rutherford y) Dmitri Mendeleev

Last Answer : ANSWER: W -- VICTOR GRIGNARD

The modern atomic theory was conceived by : w) Victor Grignard x) Daniel Rutherford y) Svante Arrhenius z) John Dalton

Description : The modern atomic theory was conceived by : w) Victor Grignard x) Daniel Rutherford y) Svante Arrhenius z) John Dalton

Last Answer : ANSWER: Z -- JOHN DALTON

Grignard reagent is chemically known as (A) Ethyl magnesium chloride (B) Methyl magnesium chloride (C) Dichlorophenol (D) Monochloroacetic acid

Description : Grignard reagent is chemically known as (A) Ethyl magnesium chloride (B) Methyl magnesium chloride (C) Dichlorophenol (D) Monochloroacetic acid

Last Answer : (A) Ethyl magnesium chloride

Chemical name of Grignard reagent is (A) Sodium thiosulphate (B) Ethyl magnesium chloride (C) Sodium sulphite (D) Sodium bicarbonate

Description : Chemical name of Grignard reagent is (A) Sodium thiosulphate (B) Ethyl magnesium chloride (C) Sodium sulphite (D) Sodium bicarbonate

Last Answer : (B) Ethyl magnesium chloride

(4) None of these Explanation: Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations. Catalysts that speed the reaction are called positive catalysts.

Description : (4) None of these Explanation: Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that ... may participate in multiple chemical transformations. Catalysts that speed the reaction are called positive catalysts.

Last Answer : Table salt gets moist during rainy season because – (1) sodium chloride is hygroscopic (2) sodium chloride is deliquescent (3) sodium chloride contains some quantity of sodium iodide (4) sodium chloride contains hygroscopic impurities like magnesium chloride

Name two reagents which can be used to distinguish between ethene and ethyne.

Description : Name two reagents which can be used to distinguish between ethene and ethyne.

Last Answer : Ans. Tollen‘s reagent

. Which of the following reagents will react with furan to form 2-furansulfonic acid? (a) SO3 in pyridine at 100°C (b) Dilute H2SO4 at 200°C (c) SO2 at 100°C (d) Dilute H2SO4 at 100°C

Description : Which of the following reagents will react with furan to form 2-furansulfonic acid? (a) SO3 in pyridine at 100°C (b) Dilute H2SO4 at 200°C (c) SO2 at 100°C (d) Dilute H2SO4 at 100°C

Last Answer : SO3 in pyridine at 100°C

Which of the following reagents will react with pyrrole to form 2- formylpyrrole? (a) HCOOH (b) CHCl3/KOH (c) H2O2 (d) (CH3CO)2O/SnCl4

Description : Which of the following reagents will react with pyrrole to form 2- formylpyrrole? (a) HCOOH (b) CHCl3/KOH (c) H2O2 (d) (CH3CO)2O/SnCl4

Last Answer : CHCl3/KOH

Which of the following reagents is used to prepare benzenediazoniumchloride from aniline?(a) NaNO2 + HCl(b) LiAlH4(c) NH2NH2 + KOH(d) NaOH

Description : Which of the following reagents is used to prepare benzenediazonium chloride from aniline? (a) NaNO2 + HCl (b) LiAlH4 (c) NH2NH2 + KOH (d) NaOH

Last Answer : NaNO2 + HCl

Which of the following reagents does not react with aniline? (a) Acetyl chloride (b) Acetic anhydride (c) Ammonia (d) Nitrous acid

Description : Which of the following reagents does not react with aniline? (a) Acetyl chloride (b) Acetic anhydride (c) Ammonia (d) Nitrous acid

Last Answer : Ammonia

Which of the following reagents can be used to distinguish between chlorobenzene and benzyl chloride? (a) alcoholic AgNO3 (b) Br2 in CCl4 (c) KCN (d) Br2 in H2O

Description : Which of the following reagents can be used to distinguish between chlorobenzene and benzyl chloride? (a) alcoholic AgNO3 (b) Br2 in CCl4 (c) KCN (d) Br2 in H2O

Last Answer : alcoholic AgNO3

Which of the following reagents can be used to distinguish between chlorobenzene and allyl chloride? (a) H2/Ni(b) Br2 in CCl4(c) Zn/HCl(d) NH2NH2

Description : Which of the following reagents can be used to distinguish between chlorobenzene and allyl chloride? (a) H2/Ni (b) Br2 in CCl4 (c) Zn/HCl (d) NH2NH2

Last Answer : Br2 in CCl4

Which of the following reagents will react with methyl group rather than thebenzene ring in methylbenzene?(a) Chlorine in the presence of uv light(b) CH3Cl in the presence of AlCl3(c) CH3COCl in the presence of AlCl3(d) Hydrogen in the presence of nickel

Description : Which of the following reagents will react with methyl group rather than the benzene ring in methylbenzene? (a) Chlorine in the presence of uv light (b) CH3Cl in the presence of AlCl3 (c) CH3COCl in the presence of AlCl3 (d) Hydrogen in the presence of nickel

Last Answer : Chlorine in the presence of uv light

Which of the following reagents will react with acetamide to form methylamine? (a) LiAlH4 (b) Br2/NaOH (c) PCl5 (d) H2/Ni

Description : Which of the following reagents will react with acetamide to form methylamine? (a) LiAlH4 (b) Br2/NaOH (c) PCl5 (d) H2/Ni

Last Answer : Br2/NaOH