Option (i) and (iii) are the answers. Phenols react with FeCl3 to create a colourful Fe3+ ion complex. Depending on the structure of the phenol examined, the hue ranges from purple to orange....
Which of the following reagents can be used to oxidise primary alcohols to aldehydes? (i) CrO3 in an anhydrous medium. (ii) KMnO4 in acidic medium. (iii) Pyridinium chlorochromate. (iv) Heat in the presence of Cu at 573K
Option (i), (iii) and (iv) are the answers. Primary alcohols can be oxidised to aldehydes using CrO3 in an anhydrous media. CrO3 serves as an oxidizer in this situation. As a result, option I is the...
Which of the following reactions will yield phenol?
Option (A), (B) and (C) are correct Diazonium salt is produced when aniline is treated with NaNO2 + HCl. The Diazonium salts are then hydrolyzed to Phenols by heating them with water. As a result,...
Which of the following are used to convert RCHO into RCH2OH? (i) H2/Pd (ii) LiAlH4 (iii) NaBH4 (iv) Reaction with RMgX followed by hydrolysis
Option (i), (ii) and (iii) are the answers. In the presence of a catalyst such as Pd, Pt, or Ni, aldehydes can be transformed to their corresponding alcohols by hydrogen. Lithium aluminium hydride...
Mark the correct increasing order of reactivity of the following compounds with HBr/HCl.(i) a < b < c (ii) b < a < c (iii) b < c < a (iv) c < b < a
Option (iii) is the answer. It's a nucleophilic substitution process that uses the $SN_1$ mechanism. The stability of the carbocation is required for the $SN_1$ mechanism to work. The presence of an...
Mark the correct order of decreasing acid strength of the following compounds.(i) e > d > b > a > c (ii) b > d > a > c > e (iii) d > e > c > b > a (iv) e > d > c > b > a
Option (ii) is the answer. The sequence of decreasing acid strength is b>d>a>c>e, with p-nitrophenol being the most acidic and p-methoxy phenol being the least acidic. The acidity is...
Which of the following is most acidic? (i) Benzyl alcohol (ii) Cyclohexanol (iii) Phenol (iv) m-Chlorophenol
Option (iv) is the answer. Alcohols have a lower acidity level than phenol. Furthermore, electron-withdrawing groups make phenols more acidic, therefore m-chlorophenol is the most acidic.
Phenol is less acidic than ______________. (i) ethanol (ii) o-nitrophenol (iii) o-methyl phenol (iv) o-methoxy phenol
Option (ii) is the answer. Because electron withdrawing $-NO_2$ groups enhance the acidity of phenols, while electron donating groups ($-CH_3$,$-OCH_3$) lower the acidity of phenols, phenol is less...
Which of the following species can act as the strongest base?
Option (ii) is the answer. The conjugate base of the weakest acid is the strongest. Because R OH is the weakest acid, $RO^-$ is the most powerful base.
IUPAC name of the compound is ______________.(i) 1-methoxy-1-methylethane (ii) 2-methoxy-2-methylethane (iii) 2-methoxypropane (iv) isopropylmethyl ether
Option (iii) is the answer. 2methoxypropane is the IUPAC name for the compound.
IUPAC name of m-cresol is ___________. (i) 3-methylphenol (ii) 3-chlorophenol (iii) 3-methoxyphenol (iv) benzene-1,3-diol
Option (i) is the answer. Because OH has a greater priority, its position on the benzene ring is number one, and the methyl group with locant number three is meta to it. 3-Methylphenol will be its...
Give IUPAC name of the compound given below.(i) 2-Chloro-5-hydroxyhexane (ii) 2-Hydroxy-5-chlorohexane (iii) 5-Chlorohexan-2-ol (iv) 2-Chlorohexan-5-ol
Option (iii) is the answer. We begin by choosing the longest carbon chain in the supplied organic molecule, as defined by IUPAC nomenclature. We use hexane because the longest carbon chain has six...
Which of the following compounds is aromatic alcohol?(i) A, B, C, D (ii) A, D (iii) B, C (iv) A
Option (iii) is the answer. Aromatic alcohols are those in which the -OH group is not directly connected to the benzene ring. As a result, option C is accurate.
The process of converting alkyl halides into alcohols involves_____________. (i) addition reaction (ii) substitution reaction (iii) dehydrohalogenation reaction (iv) rearrangement reaction
Option (ii) is the answer. Since the $X^-$ group is replaced by the $OH^-$ group, the process of turning alkyl halides into alcohols may be written as: R−X→R−OH. This is a nucleophilic substitution...
CH3CH2OH can be converted into CH3CHO by ______________. (i) catalytic hydrogenation (ii) treatment with LiAlH4 (iii) treatment with pyridinium chlorochromate (iv) treatment with KMnO4
Option (iii) is the answer. Pyridinium chlorochromate (PCC), a combination of chromium trioxide, pyridine, and HCl, produces a high yield of aldehydes while preventing carboxylic acid oxidation....
What is the correct order of reactivity of alcohols in the following reaction? R—OH + HCl →(ZnCl2) R—Cl + H2O (i) 1° > 2° > 3° (ii) 1° < 2° > 3° (iii) 3° > 2° > 1° (iv) 3° > 1° > 2°
Option (iii) is the answer. The Lucas reagent is a combination of concentrated HCl and dry anhydrous $ZnCl_2$, and the reaction is known as the Lucas test. It's used to figure out whether a...
Monochlorination of toluene in sunlight followed by hydrolysis with aq. NaOH yields. (i) o-Cresol (ii) m-Cresol (iii) 2, 4-Dihydroxytoluene (iv) Benzyl alcohol
Option (iv) is the answer. Explanation: In the presence of light, halogenation follows the free radical pathway, and therefore reacts with the alkyl group to produce halo alkyl. In the presence of...
What is the structure and IUPAC name of glycerol?
Glycerol, commonly known as glycerin, is a triol molecule found in both plant and animal lipids. It's a substance that's utilised in dermatological treatments. It has mostly been utilised as a...
Write the IUPAC name of the following compounds.
(A)The compound's IUPAC name is 3-Ethyl-5-methyl hexane-2,4-diol. (B) The compound's IUPAC name is 1-Methoxy-3-nitrocyclohexane
Write the IUPAC name of the compound given below.
The compound's IUPAC name is 3-Methylpent-2-ene-1,2-diol. In the structure shown, the longest carbon atom chain is 5. Except for one double bond between C2 and C3 atoms, all carbon atom bonds are...
Name the factors responsible for the solubility of alcohols in water.
The following factors influence the solubility of alcohols in water: (i)Hydrogen bonding (ii)The size of the alkyl or aryl groups is the second factor to consider. (iii)The molecular mass of...
What is denatured alcohol?
Alcohols used for drinking are rendered unsuitable for human consumption by combining them with copper sulphate and pyridine, which give the liquid a yellow colour and a terrible odour,...
Suggest a reagent for the following conversion.
The oxidation of secondary alcohol into a ketone is seen in the chemical process above. Using oxidising agents such as chromic anhydride (CrO3), Pyridinium chlorochromate (PCC), and others, this is...
Out of 2-chloroethanol and ethanol which is more acidic and why?
Because of the presence of chlorine, which is an electron-withdrawing group, 2-chloroethanol is more acidic. The electron density in the –O-H bond decreases as a result of the negative inductive...
Suggest a reagent for conversion of ethanol to ethanal.
As reagents, PCC or Pyridinium chlorochromate might be employed. The oxidation of primary alcohol to an aldehyde is seen in the diagram above.
Suggest a reagent for conversion of ethanol to ethanoic acid.
For the afore mentioned reaction, acidified KMnO4 might be employed as a reagent. The oxidation of primary alcohol to a carboxylic acid is seen in the diagram above.
Out of o-nitrophenol and p-nitrophenol, which is more volatile? Explain.
O-nitrophenol is more volatile due to intramolecular hydrogen bonding between the NO2 and OH groups.
When phenol is treated with bromine water, a white precipitate is obtained. Give the structure and the name of the compound formed.
2,4,6-tribromophenol is the name of the chemical produced in this process. The compound's structure is as follows:
Arrange the following compounds in increasing order of acidity and give a suitable explanation. Phenol, o-nitrophenol, o-cresol
o-cresol < Phenol < o-nitrophenol. NO2 o-nitrophenol becomes more acidic due to the presence of the electron-withdrawing group. The electron-releasing group in remaining reduces the acidic...
Alcohols react with active metals e.g. Na, K etc. to give corresponding alkoxides. Write down the decreasing order of reactivity of sodium metal towards primary, secondary and tertiary alcohols
The following is a list of sodium metal's reactivity to alcohols in decreasing order: Primary alcohols are followed by secondary alcohols and finally tertiary alcohols. Because of two factors,...
What happens when benzene diazonium chloride is heated with water?
When benzene diazonium chloride is heated with water, it produces phenol as well as nitrogen gas and hydrochloric acid as by-products.
Arrange the following compounds in decreasing order of acidity. H2O, ROH, HC ≡ CH
The acidity of the following substances is listed in decreasing order: H2O > ROH > HC ≡ CH Because the carbon atoms here are sp hybridised, the electron density on the carbon atom is greater,...
Name the enzymes and write the reactions involved in the preparation of ethanol from sucrose by fermentation.
The enzymes involved in the fermentation of sucrose to produce ethanol are known as invertase and zymase. Sucrose is converted to glucose and fructose by invertase. The glucose and fructose are then...
How can propane-2-one be converted into tert- butyl alcohol?
Propane-2-one is hydrolyzed after being treated with CH3MgBr in the presence of dry ether (Grignard reagent).
Explain why the OH group in phenols is more strongly held as compared to OH group in alcohols
The phenol –OH group is immediately linked to the benzene ring's sp2hybridized carbon atom. The carbon-oxygen bond length in phenol is shorter than that in alkyl alcohol, which is related to the...
Explain why nucleophilic substitution reactions are not very common in phenols.
The ortho- and para-positions of the benzene ring become electron-rich as a result of the resonance, activating it for electrophilic substitution reactions. As a result, nucleophilic substitution...
Preparation of alcohols from alkenes involves the electrophilic attack on an alkene carbon atom. Explain its mechanism.
Step 1: Alkene protonation and production of a carbocation Step 2: Water's nucleophilic assault Step 3: Deprotonation occurs, resulting in the formation of alcohol. H30+ is now...
Explain why is O=C=O nonpolar while R—O—R is polar.
The dipole moments of the two C=O bonds are exactly equal and opposite, making O=C=O nonpolar. As a result, they cancel each other out, resulting in a net dipole moment of zero for O=C=O. Because...
Why is the reactivity of all the three classes of alcohols with conc. HCl and ZnCl2 (Lucas reagent) different?
This is due to the alkyl group's steric barrier and the carbocation's stability. Because the 1° carbocation is the least stable, primary alcohol has no reaction at ambient temperature. At ambient...
Write steps to carry out the conversion of phenol to aspirin.
Acetylsalicylic acid is another name for aspirin. The phenoxide ion is created by treating phenol with NaOH. The phenoxide ion is subsequently electrophilically substituted with CO2 to produce...
Nitration is an example of aromatic electrophilic substitution and its rate depends upon the group already present in the benzene ring. Out of benzene and phenol, which one is more easily nitrated and why?
The presence of the hydroxyl group in phenol causes it to be more nitrated. The ortho- and para-positions in the benzene ring become electron-rich due to the resonance effect induced by the –OH...
In Kolbe’s reaction, instead of phenol, phenoxide ion is treated with carbon dioxide. Why?
Because phenoxide ion is more reactive towards electrophilic aromatic substitution than phenol, phenoxide ion is treated with carbon dioxide (a weak electrophile) in Kolbe's process.
The dipole moment of phenol is smaller than that of methanol. Why?
The dipole moment of phenol is smaller than that of methanol due to the electron-withdrawing effect of the phenyl ring. Due to the resonance, the polarity of the C-O bond in phenol decreases.
Ethers can be prepared by Williamson synthesis in which an alkyl halide is reacted with sodium alkoxide. Di-tert-butyl ether can’t be prepared by this method. Explain.
Williamson synthesis, in which an alkyl halide is reacted with sodium alkoxide, can be used to make ethers. This technique cannot be used to make di-tert-butyl ether because elimination takes...
Why is the C—O—H bond angle in alcohols slightly less than the tetrahedral angle whereas the C—O—C bond angle in ether is slightly greater?
Due to repulsion between the unshared pair of electrons or the lone pair of electrons on the oxygen atom, the C—O—H bond angle in alcohols is somewhat smaller than the tetrahedral angle.
Explain why low molecular mass alcohols are soluble in water.
This is due to the presence of intermolecular hydrogen bonding between alcohol molecules due to the presence of the OH group. The impact of the polar character of the –OH group of alcohol is...
Explain why p-nitrophenol is more acidic than phenol.
Because of the presence of an electron-withdrawing group, the -NO2 group, which improves the acidic strength of the molecule by stabilising the phenoxide ion, para-nitrophenol is more acidic than...
Explain why alcohols and ethers of comparable molecular mass have different boiling points?
Because alcohols contain intermolecular hydrogen bonding, their boiling temperatures differ from those of ethers of comparable molecular mass.
The carbon-oxygen bond in phenol is slightly stronger than that in methanol. Why?
Reason: (i) The carbon-oxygen bond obtains a partial double bond character due to the resonance. As a result, the carbon-oxygen bond in phenol shrinks in size. ii) Oxygen is directly connected to a...
Write structures of the compounds whose IUPAC names are as follows:
(i) Cyclopent – 3 – en – 1 – ol (ii) 4-Chloro-3-ethylbutan-1-ol. Solution: (i) (ii)
Write structures of the compounds whose IUPAC names are as follows:
(i) Cyclohexylmethanol (ii) 3 – Cyclohexylpentan – 3 – ol Solution: (i) (ii)
Write structures of the compounds whose IUPAC names are as follows:
(i) 1 – Ethoxypropane (ii) 2 – Ethoxy – 3 – methylpentane Solution: (i) structure of 1 – Ethoxypropane : (ii) Structure of 2 – Ethoxy – 3 – methylpentane...
Write structures of the compounds whose IUPAC names are as follows:
(i) 3 , 5 – Dimethylhexane – 1 , 3 , 5 – triol (ii) 2, 3 – Diethylphenol Solution: (i) (ii)
Write structures of the compounds whose IUPAC names are as follows:
(i) 2 – Methylbutan – 2 – ol (ii) 1–Phenylpropan–2–ol Solution: (i) (ii)
Give a mechanism for this reaction. (Hint: The secondary carbocation formed in step II rearranges to a more stable tertiary carbocation by a hydride ion shift from 3rd carbon atom)
Solution: The following procedure is involved in the above-mentioned steps of the reaction: Step 1: Protonation Step 2: Forming 2 ° carbonation by eliminating the water molecule Step 3: Rearranging...
Show how would you synthesize the following alcohols from appropriate alkenes?
(i) (ii) Solution: All the alcohols are formed by the hydration of alkenes in the acidic medium. The addition follows Markownikov’s rule. (i) 1-Methylcyclohexene can be used in the reaction. (ii)...
Write equations of the following reactions:(i) Bromination of anisole in ethanoic acid medium (ii) Friedel-Craft’s acetylation of anisole.
(i) (ii)
Write equations of the following reactions: (i) Friedel-Crafts reaction – alkylation of anisole.(ii) Nitration of anisole.
(i) (ii)
Write the mechanism of the reaction of HI with methoxymethane.
Step 1: Protonation of methoxymethane : Step 2: Nucleophilic attack of I – : Step 3: The methanol produced in the previous step is used to combine with another HI molecule, resulting in the...
Explain the fact that in aryl alkyl ethers.
(i) the alkoxy group activates the benzene ring towards electrophilic substitution and (ii) it directs the incoming substituents to ortho and para positions in the benzene ring. (i) The presence of...
Write the equation of the reaction of hydrogen iodide with:
(i) 1-propoxypropane (ii) methoxybenzene (iii) benzyl ethyl ether
Preparation of ethers by acid dehydration of secondary or tertiary alcohols is not a suitable method. Give reason.
The production of ethers with alcohol dehydration is a bimolecular process ( SN 2) that involves an alcohol molecule attacking a protonated alcohol molecule. The alkyl group should be free in the...
How is 1-propoxypropane synthesised from propan-1-ol? Write the mechanism of this reaction.
The process of dehydration is used to synthesize 1- propoxypropane from propan –1– ol. In the presence of protic acids (such as H2SO4, H3PO4), propan-1-ol dehydrates to yield 1 – propoxypropane....
How is 1-propoxypropane synthesized from propan-1-ol? Write the mechanism of this reaction.
Dehydration reaction can be used to synthesise 1- propoxypropane from propan –1– ol. In the presence of protic acids (such as H2SO4, H3PO4), propan-1-ol dehydrates to yield 1 –...
Illustrate with examples the limitations of Williamson synthesis for the preparation of certain types of ethers.
Williamson's synthesis is a flexible approach for making symmetrical and unsymmetrical ethers. However, careful reactant selection is required for the synthesis of unsymmetrical ethers. Because the...
Write the names of reagents and equations for the preparation of the following ethers by Williamson’s synthesis:
(i) 2-Methoxy-2-methylpropane (ii) 1-Methoxyethane
Write the names of reagents and equations for the preparation of the following ethers by Williamson’s synthesis:
(i) 1-Propoxypropane (ii) Ethoxybenzene
Give IUPAC names of the following ethers:
1 -Ethoxy-4 -4 – dimethyl cyclohexane Ethoxybenzene
Give IUPAC names of the following ethers:
(i) 4-Nitroanisole(ii) 1-Methoxypropane
Give IUPAC names of the following ethers:
(i)1-Ethoxy-2-methylpropane(ii) 2-Chlorlo-l-methoxy ethane
Give a reason for the higher boiling point of ethanol in comparison to methoxymethane.
Because of the presence of the – OH group in ethanol, intermolecular H – bonding occurs, resulting in molecule interaction. To break these hydrogen bonds, more energy is required. Methoxymethane, on...
Give a reason for the higher boiling point of ethanol in comparison to methoxymethane.
Because of the presence of the –OH group in ethanol, intermolecular H–bonding occurs, resulting in molecule interaction. To break these hydrogen bonds, more energy is required. Methoxymethane, on...
Name the reagents used in the following reactions:
(i) Dehydration of propan-2-ol to propene.(ii) Butan-2-one to butan-2-ol. (i) Concentrated H2SO4 or H3PO4 (ii) catalytic hydrogenation or sodium borohydride (NaBH4) or lithium aluminium hydride...
Name the reagents used in the following reactions:
(i) Bromination of phenol to 2,4,6-tribromophenol.(ii) Benzyl alcohol to benzoic acid. (i) Bromine water (ii) Acidified potassium permanganate
Name the reagents used in the following reactions:
(i) Oxidation of primary alcohol to a carboxylic acid.(ii) Oxidation of primary alcohol to aldehyde. (i) NaBH4 or LiAlH4 to acidified KMnO4 (ii) Pyridinium chlorochromate (PCC)
How are the following conversions carried out?
(i) Ethyl magnesium chloride → Propan-1-ol.(ii) Methyl magnesium bromide → 2-Methylpropan-2-ol. (i) When ethyl magnesium chloride reacts with methane, an adduct is formed, resulting in propan–1–ol...
How are the following conversions carried out?
(i) Propene → Propan-2-ol.(ii) Benzyl chloride → Benzyl alcohol. (i) Propene is converted to propan–2–ol when it is treated with water in the presence of an acid catalyst. (ii) If benzyl chloride is...
Write the mechanism of acid dehydration of ethanol to yield ethene.
The mechanism of acid dehydration of ethanol to yield ethene takes place in the following three steps : Step 1 : Formation of ethyl oxonium by protonation of ethanol : Step 2 : Formation of a...
Explain the following with an example.
(i) Williamson ether synthesis.(ii) Unsymmetrical ether. (i) Williamson's ether synthesis is the process of obtaining ethers by treating an alkyl halide with a suitable sodium alkoxide. The sodium...
Explain the following with an example. (i) Kolbe’s reaction, (ii) Reimer-Tiemann reaction.
(i) Kolbe's reaction: When sodium phenoxide is heated with C02 at 400°C under 4-7 atmospheres and then acidified, the main result is 2-hydroxybenzoic acid (salicylic acid), with a minor amount of...
Give equations of the following reactions:
(i) Dilute HNO3 with phenol.(ii) Treating phenol with chloroform in the presence of aqueous NaOH. (i) (ii)
Give equations of the following reactions: (i) Oxidation of propan-1-ol with alkaline KMnO4solution, (ii) Bromine in CS2, with phenol.
(i) (ii)
Explain how does the –OH group attached to a carbon of benzene ring activates it towards electrophilic substitution.
Because the – OH group works as an electron-donating group, the electron density in the benzene ring increases. The resonance structure of phenol, as seen below, clearly demonstrates this. As a...
Explain why ortho nitrophenol is more acidic than ortho methoxyphenol.
An electron-withdrawing group is a nitro – group. The electron density in the O – H bond is reduced by the presence of this group in the ortho position. As a result, it is simpler to give away a...
Give two reactions that show the acidic nature of phenol. Compare the acidity of phenol with that of ethanol.
The acidic nature of phenol can be proven with the two reactions shown below : (i) Reaction with sodium: Phenol reacts with active metals like sodium to liberate Hydrogen gas. (ii) Reaction with...
Show how will you synthesize:
(i) 1-phenylethanol from a suitable alkene.(ii) cyclohexylmethanol using an alkyl halide by an SN2 reaction.(iii) pentan-1-ol using a suitable alkyl halide? (i) 1 – phenylethanol can be made by...
You are given benzene, conc.H2SO4and NaOH. Write the equations for the preparation of phenol using these reagents.
Write a chemical reaction for the preparation of phenol from chlorobenzene.
Chlorobenzene is mixed with NaOH (at 623 K and 320 atm pressure) to make sodium phenoxide, which is then acidified to produce phenol.
Write the mechanism of hydration of ethene to yield ethanol.
In the mechanism of hydration of ethene to create ethanol, three steps are involved. These are the actions to take: Step 1: Electrophilic action of H3O+ protonates ethene to create carbocation:...
Give the equations of reactions for the preparation of phenol from cumene.
Cumene is first oxidized in the presence of air to produce cumene hydroperoxide, which is then used to make phenol. The cumene hydroxide was then treated with dilute acid to produce phenol and...
While separating a mixture of ortho and para nitrophenols by steam distillation, name the isomer which will be steam volatile. Give reason.
o-nitrophenol and p-nitrophenol both have intramolecular H–bonding. Because intermolecular bonding exists in p–nitrophenol, the molecules are tightly bound together. As a result, o – nitrophenol is...
Give the structures and IUPAC names of monohydric phenols of molecular formula, C7H8O.
What is meant by the hydroboration-oxidation reaction? Illustrate it with an example.
The hydroboration–oxidation reaction is one in which borane is used to initiate the oxidation process. Propan–1–ol, for example, is made by subjecting propene to a hydroboration – oxidation...
Explain why propanol has a higher boiling point than that hydrocarbon, butane.
Propanol undergoes intermolecular H-bonding due to the presence of the – OH group. Butane, on the other hand, does not have the same advantages. In order to dissolve the intermolecular hydrogen...
(i) Draw the structures of all isomeric alcohols of molecular formula C5H12O and give their IUPAC names. (ii) Classify the isomers of alcohols in question.
(a) CH3-CH2-CH2-CH2-CH2-OH Pentan – 1 – ol (1 °) (ii) Primary alcohol: Pentan – 1 – ol ; 2 – Methylbutan – 1 – ol ; 3 – Methylbutan – 1 – ol ; 2, 2 – Dimethylpropan – 1 – ol Secondary alcohol:...
Write IUPAC names of the following compounds:
(i) 1 – Phenoxyheptane (ii) 2 – Ethoxybutane
Write IUPAC names of the following compounds:
(i) 1 – Methoxy – 2 – methyl propane (ii) Ethoxy benzene
Write IUPAC names of the following compounds:
(i) 2, 5 – Dimethylphenol (ii) 2, 6 – Dimethylphenol
Write IUPAC names of the following compounds:
(i) 2-Methylphenol (ii) 4 – Methyl phenol
Write IUPAC names of the following compounds:
(i) Butane – 2, 3 – diol (ii) Propane – 1, 2, 3 – triol
Write IUPAC names of the following compounds:
Solutions: (i) 2, 2, 4 -Trimethylpentan – 3 – ol (ii) 5 – Ethylheptane – 2, 4 – diol