Write equations of the following reactions: Bromination of anisole in ethanoic acid medium. (a) HCHO. (b) Cone. (ii) Ethoxybenzene Question 2. Identify allylic alcohols in the above examples. Which compound is known as oil of winter green : (iii) Pentan-l-ol using a suitable alkyl halide ? Show how would you synthesise the following alcohols from appropriate alkenes? (i) 2-Methylbutan-2-ol By it misuse of ethanol as a beverage is controlled. (i) 1-Propoxypropane Question 27. Hydrocarbons do not form hydrogen bond, thus their boiling point is comparatively less. The method according to claim 8 wherein the reaction zone of the reactor is maintained at about 50mm Hg. Explain this fact. After the formation of ethene, it is removed to shift the equilibrium in a forward direction. Answer: The acceptable reflux rate range is about 1 ml to about 8 mls/minute. Therefore, the b.p. 0000007805 00000 n The protonated alcohol loses a molecule of H2O to form a stable 2° or 3° carbo-cation. Further more after the loss of proton o-methoxy- phenoxide ion left is destabilized by resonance. The vapor reactor heat tape is turned on and the voltage adjusted just high enough to prevent condensation of 3 methyl-anisole in the vapor reactor.The Br2 feed valve is opened and adjusted to give 0.2 mls ofvapor per minute. Explanation of acidic nature of phenol: One possible explanation why phenols are stronger acids as compared to alcohols is that phenols exist as a resonance hybrid. Illustrate it with an example. Classify the following as primary, secondary and tertiary alcohols : Anisole Bromination Field of Invention 1. (iii) Bromination of anisole in ethanoic acid medium. In set (A) the Br group is activated by the electron withdrawing effect of —NO2 group. (c) Reaction with 2,4 dinitrophenyl hydrazine (xi) 1-Phenoxyheptane (d) Methyl salicylate. (b) Friedel Crafts reaction (ii) Nitration of anisole : Anisole reacts a mixture of concentrated sulphuric and nitric acids to yield a mixture of ortho and para nitroanisole. When the reaction is just about done, the column temp will begin to rise. (a) Methyl alcohol, Question 17. 0000001048 00000 n Vaporization can be accomplished by conventional means such as application of heat, and/or optionally reduction of reactor pressure, preferably both steps.Bromine vapor is generated from a bromine source such as by heating liquid Brz above its boiling point 331 Xelvin to form a gas. (i) Friedel-Craft’s reaction – alkylation of anisole. (iii) 4-Nitro anisole Give labelled diagram. Answer: !Those who know Atharva they only answer (a) (CH3)3 C-OH (iv) Unsymmetrical ether. The mechanism of acid dehydration of ethanol to yeild ethene involes the following three steps: Step 1 : Protonation of ethanol to form ethyl oxonium ion : (ii) Nitration of anisole. (i) When ethyl alcohol is heated in excess of cone. What do you understand by Methylated spirit or denaturing alcohol ? It works on the counter current principle and the steam and wash travel in opposite directions through the still. Such maintenance of 3-alkyl anisole in the gaseous phase is readily accomplishable by arranging a reflux of the partially reacted reaction zone effluent to the rectifying column, contined heat input to the reboiler, and maintenance of the reaction zone at about 10 to 30c higher temperature than the entering vapor. (iii) Bromination of anisole in ethanoic acid medium. Bromine (b.p. Now it is attacked by another alcohol molecule. Write equations of the following reactions: (iv) Friedel-Craft’s acetylation of anisole : Question 32. (i) How can we obtain phenol from benzene diazonium chloride ? (d) Chloroform. (ii) Ethanol from diethyl ether Question 10. It is acidic and dissolve in bases to form salt. HCl is known as Lucas reagent. 4. 0000007584 00000 n Describe the laboratory method of preparation of diethyl ether. Most acidic among the four compound is : 331K) is established as a vapor in the reactor and introduced to the reaction zone commingling with the established 3-alkylanisole vapor. Write chemical reaction for the preparation of phenol from chloroben zene. Which of the compound is Aspirin : (iv) Benzene How is it prepared ? When one of the groups in unsymmetrical ether is tertiary, then the halide formed is tertiary halide. In aryl alkyl ethers, due to the +R effect of the aikoxy group, the electron density in the benzene ring increases as shown in the following resonance structure. Methylated spirit is 90% ethanol to which nauseating materials like methyl alcohol, pyridine or mineral naphtha have been added. (c) C6H5CHO You can specify conditions of storing and accessing cookies in your browser. If a blood red colour is obtained, the original alcohol is primary. Thus, alkyl halide should be derivde from ethanol and alkoxide ion from 3-methyl pentan-2-ol. The fermentation reaction starts and the enzyme Invertase (From Yeast) converts sucrose into glucose and fructose which are then converted into ethanol by Zymase (From Yeast). (iv) Ethanol from Glucose : Question 7. (c) m – nitrophenol, Question 3. Methyl alcohol and acetone vapours pass over and are condensed. A typical precut is 4.6% of crude weight or 24g which contains about 22g of 3-methyl-anisole to be recycled. If carbon tetrachloride is used in place of chloroform, salicylic acid is obtained as the main product. Description of Related Art Present methods for bromination of 3-alkyl anisole, particularly 3-methyl-anisole involves liquid reaction of bromine and 3 methyl-anisole. What are molasses ? Ethyl alcohol and phenol both contain — OH group. (d) Alcohol is amphoteric. (c) C2H5—OH In case of C2H5OH there is strong intermolecular hydrogen bonding between the molecules of alcohol. Answer: Favourable temperature: It is between 25-35°C. This is on ac¬count of chelation (intramolecular H—bonding) in the molecule of o-nitrophenol. (i) Reimer-Tiemann reaction 0000060303 00000 n (d) Cone. If a blue colour is obtained, the alcohol is secondary. Answer: Answer in one word/sentence : Alcohols, Phenols and Ethers Short Answer Type Questions. Purification: Ether contain ethanol, water and sulphuric acid as impurities. Question 33. (ii) Removal of water, (iii) Elimination of β-hydrogen in the form of proton by base (bisulphate ion) (iii) Ethyl acetate from ethanol Answer: Acid hydration of Pent-2-ene produces Penton – 3-ol along with penton-2-ol. Question 24. (b) With HBr : Both the alcohols react with HBr to give corresponding alkyl bromides. Lucas reagent is : Diethyl ether is prepared in the laboratory and industry by the Williamson continuous etherification process, i.e., by heating ethanol (in excess) with concentrated sulphuric acid. (a) The reactions showing acidic character of phenol are: (iii) Bromination of anisole in ethanoic acid medium. Explain, why ortho nitrophenol is more acidic than ortho methoxyphenol ? 0000011242 00000 n Question 18. (iii) A tertiary alcohol is resistant to oxidation in neutral or alkaline solutions but is readily oxidized by an acid oxidizing agent giving a mixture of ketone and acid each having lesser number of carbon atoms than the original alcohol. Boiling point of alcohols is much higher than hydrocarbons of nearly similar molecular mass due to inter molecular hydrogen bond. 0000012467 00000 n (i) Reimer-Tiemann reaction : When phenol is treated with chloroform in presence of aqueous sodium hydroxide at 60°C, o-Hydroxy benzaldehyde (Salicylaldehyde) and p-Hydroxy benzaldehyde are formed. (i) 1-Ethoxy-2-methylpropane Answer: Answer: The system is reduced to a pressure of 50mm Hg, however lOmm ~o about 200mm is an acceptable range. 12. 0000012242 00000 n bakelite is formed. Why the b.p. Answer: In case of pent-2-one, both the carbon atoms of double bond have one H-atom. Answer: Question 13. Direct addition of water to ethene in presence of an acid does not occur. Answer: Example : Reaction of ethyl bromide with sodium ethoxide gives diethyl ether Compare acidity of phenol with that of ethanol. Answer: Question 5. 0000001992 00000 n (a) HCHO (d) Alcohol. The above temperatures are based on about 50mm Hg pressure for the system. 0000103020 00000 n Boiling point of higher than corresponding alkane. The method according to claim 7 wherein the reaction zone of the reactor is maintained at about 50mm Hg pressure. Question 33. (i) 2,2,4-Trimethyl pentan-3-ol (a) Cone. C2H5OH and CH3OCH3 both have same molecular formula (C2H6O) but the b.p. In substituted phenols, the presence of electron withdrawing group (-R effect) such as -NO2 group, increases the acidic strength of phenol, ortho and para nitrophenoxide ions are more stable (because of additional resonance structures show in boxes) than phenoxide ion due to effective delocalisation of negative charge in phenoxide ion. The vapours are passed through hot milk of lime which retains acetic acid as non-volatile calcium acetate. Write the equations for the preparation of phenol using these reagents. -R effect results in +ve charge on O-atom and hence facilitates the release of proton. If a tertiary alkyl halide is used, an alkene is the only reaction product and no ether is formed.
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