Chemistry Notes for class 12 Chapter Alcohols, Phenols and Ethers. Alcohols and Phenols. Alcohols and phenols are formed when a hydrogen atom in. Class XII Chapter 11 – Alcohols Phenols and Ethers Chemistry Question Write IUPAC names of the following compounds: (i) (ii) (iii) (iv) (v) (vi) (vii) (viii). Alcohols, Phenols and caite.info - Download as PDF File .pdf), Text File .txt ) or read online.
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After studying this Unit, you will be able to. • name alcohols, phenols and ethers according to the IUPAC system of nomenclature;. • discuss the reactions. Free PDF download of Class 12 Chemistry revision notes & short key-notes for Chapter 11 - Alcohols, Phenols and Ethers to score high marks in exams, prepared by expert Chemistry teachers from latest edition of CBSE(NCERT) books. Previous Year Question Papers CBSE Class Learn to recognize the alcohol, phenol, and ether functional groups. • Learn the IUPAC system for naming alcohols, phenols, and ethers. • Learn the important.
Give two reactions that show the acidic nature of phenol. The introduction of acetyl CH3CO- group in phenols is known as acetylation. Get this solution now! Download pdf. Ethers Ethers are the organic compounds in which two alkyl or aryl groups are attached to a divalent oxygen.. Register now. 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 benzene ring.
How are the following conversions carried out?
Answer i If propene is allowed to react with water in the presence of an acid as a catalyst, then propanol is obtained. Name the reagents used in the following reactions: Give reason for the higher boiling point of ethanol in comparison to methoxymethane.
Extra energy is required to break these hydrogen bonds. On the other hand, methoxymethane does not undergo H-bonding. Hence, the boiling point of ethanol is higher than that of methoxymethane.
Illustrate with examples the limitations of Williamson synthesis for the preparation of certain types of ethers. Answer The reaction of Williamson synthesis involves SN2 attack of an alkoxide ion on a primary alkyl halide. But if secondary or tertiary alkyl halides are taken in place of primary alkyl halides, then elimination would compete over substitution. As a result, alkenes would be produced. This is because alkoxides are nucleophiles as well as strong bases.
Hence, they react with alkyl halides, which results in an elimination reaction. How is 1-propoxypropane synthesised from propanol? Write mechanism of this reaction. Answer 1-propoxypropane can be synthesized from propanol by dehydration. The mechanism of this reaction involves the following three steps: Protonation Step 2: Nucleophilic attack Step 3: Deprotonation Question Preparation of ethers by acid dehydration of secondary or tertiary alcohols is not a suitable method.
Answer The formation of ethers by dehydration of alcohol is a bimolecular reaction SN2 involving the attack of an alcohol molecule on a protonated alcohol molecule. In the method, the alkyl group should be unhindered. In case of secondary or tertiary alcohols, the alkyl group is hindered. As a result, elimination dominates substitution. Hence, in place of ethers, alkenes are formed. Write the equation of the reaction of hydrogen iodide with: 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 benzene ring.
Thus, benzene is activated towards electrophilic substitution by the alkoxy group. As a result, the incoming substituents are directed to the ortho and para positions in the benzene ring.
Write the mechanism of the reaction of HI with methoxymethane. Answer The mechanism of the reaction of HI with methoxymethane involves the following steps: Protonation of methoxymethane: When HI is in excess and the reaction is carried out at a high temperature, the methanol formed in the second step reacts with another HI molecule and gets converted to methyl iodide Question Write equations of the following reactions: Show how would you synthesise the following alcohols from appropriate alkenes?
Thus, the first reaction is preferred over the second one to get pentanol.
When 3-methylbutanol is treated with HBr, the following reaction takes place: Give a mechanism for this reaction. The secondary carbocation formed in step II rearranges to a more stable tertiary carbocation by a hydride ion shift from 3rd carbon atom. Answer The mechanism of the given reaction involves the following steps: Re-arrangement by the hydride-ion shift Step 4: Classify the following as primary, secondary and tertiary alcohols: Identify allylic alcohols in the above examples.
Answer The alcohols given in ii and vi are allylic alcohols.
Show how are the following alcohols prepared by the reaction of a suitable Grignard reagent on methanal? Write structures of the products of the following reactions: Predict the major product of acid catalysed dehydration of i 1-methylcyclohexanol and ii butanol Answer i. Ortho and para nitrophenols are more acidic than phenol. Draw the resonance structures of the corresponding phenoxide ions. Write the equations involved in the following reactions: Reimer-Tiemann reaction ii.
Write the reactions of Williamson synthesis of 2-ethoxymethylpentane starting from ethanol and 3-methylpentanol.
Answer In Williamson synthesis, an alkyl halide reacts with an alkoxide ion. Also, it is an SN2 reaction. In the reaction, alkyl halides should be primary having the least steric hindrance.
Hence, an alkyl halide is obtained from ethanol and alkoxide ion from 3- methylpentanol. Which of the following is an appropriate set of reactants for the preparation of 1- methoxynitrobenzene and why? In set i , sodium methoxide CH3ONa is a strong nucleophile as well as a strong base.
Hence, an elimination reaction predominates over a substitution reaction. Predict the products of the following reactions: Related Papers. By Yadu Ramachandran. By Dhirendra Kumar. Chemistry test papers. By tabish patvi. By Samu Joy. By Sachin Malik. Download pdf. Remember me on this computer. Enter the email address you signed up with and we'll email you a reset link. Acid strength of alcohols Electron releasing group increases electron density on oxygen to decrease the polarity of — OH bond.
Phenol is more acidic than alcohols due to stabilisation of phenoxide ion through resonance.
The introduction of acetyl CH3CO- group in phenols is known as acetylation. Acetylation of salicylic acid produces aspirin.
Greater the number of alkyl groups present. As a result. H2SO4 is used to remove water. Acidic catalyst converts hydroxyl group into a good leaving group.
In this test. This is because onitrophenol is steam volatile due to intramolecular hydrogen bonding while p nitrophenol is less volatile due to intermolecular hydrogen bonding which causes the association of molecules. Similarly with carbon tetrachloride and alkali.
It is prepared as follows. Dihydric Alcohols These are generally called glycols because of their sweet taste. It is used In the preparation of various beverages containing different percentages. It is obtained by destructive distillation of wood. Drinking of methanol causes blindness. Pyroligneous add.
Methods of Preparation www. Method of Preparation www. Trihydric Alcohols Glycerol or glycerine. It is a colourless. CH2OH is the first member of this group. Because of its tendency of formation of H-bonds. Chemical Properties It gives all the general reactions of -OH group.
The per-iodic acid cleavage of 1. It is sweet in taste and steam volatile. Due to excessive H-bonding. Some of its specific reactions are: Glyceryl trinitrate or tri nitroglycerine. It is soluble in water but insoluble in ether. Physical Properties 1.
Mixture of TNG and cellulose trinitrate is called blasting gelatin. These are the functional isomers of alcohols. Ethers Ethers are the organic compounds in which two alkyl or aryl groups are attached to a divalent oxygen.. Preparation of Ethers www. These also exhibit chain isomerism and metamerism. With HIO4 periodic acid. Physical Properties of Ethers Ethers are polar but insoluble inH20 and have low boiling point than alcohols of comparable molecular masses because ethers do not form hydrogen bonds with water.
Chemical Reactions of Ether i Reaction with HX Ethers with two different alkyl groups are also cleaved in the same manner and results in the formation of a primary halide or smaller and less complex alkyl halide by S N2 mechanism. Dimethyl ether is used as refrigerant and as a solvent at low temperature.
Uses of Ethers 1. Diethyl Ether is used as an anaesthesia in surgery. Flag for inappropriate content. Related titles. Chemistry Notes for class 12 Chapter 15 Polymers. Chemistry Notes for Class 12 Chapter 3 Electrochemistry.
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