Tiêu đề 12. ALDEHYDES KETONES AND CARBOXYLIC ACIDS.pdf ✅

Aldehydes and Ketones SESSION − 1 AIM ✓ To discuss the structure of carbonyl compounds and its nomenclature Aldehydes and Ketones are organic compounds which contain a carbonyl group and therefore, these compounds are collectively called carboxyl compounds. Both have general formula CnH2nO. The above structure indicates that in aldehyde carbonyl group is attached to one hydrogen atom and one alkyl or aryl group, while in ketones, it is attached to two alkyl or aryl groups. Aldehyde is always presents at terminal carbon whereas ketone is never at terminal. Aromatic aldehydes are compounds in which the −CHO group is directly attached to an aromatic ring. The compounds in which the −CHO group is not directly attached to the ring are considered as aryl substituted aliphatic aldehydes. Aromatic ketones are compounds in which a group is attached to either two aryl groups or one aryl and on alkyl group. If the two groups are the same in a ketone, it is called simple ketone. If the two groups are different, it is called mixed ketone. Nomenclature:- Common and IUPAC names of some aldehydes and ketones Structure Common name IUPAC name Aldehydes 1.HCHO Formaldehyde Methanal 2.CH3CHO Acetaldehyde Ethanal 3.CH3 − CH2 − CHO Propionaldehyde Propanol
4.CH3 − CH2 − CH2 − CHO n- Butyraldehyde Butanal 5 Isobutyraldehyde 2-Methyl propanal 6. β −Methyl butyraldehyde 3 −Methyl Butanal 7.CH3 − CH = CH − CHO Crotonaldehyde But-2-enal 8. O- Tolualdehyde 2- Methyl Benzaldehyde 9 γ −Methyl cyclohexane carbaldehyde 3- Methyl cyclohexamecarbaldehyde 10. O- hydroxybenzaldehyde (salicyladehyde) 2-Hydroxy benzaldehyde Ketones: 1. Dimethyl Ketone (Or)Acetone Propanone 2. Ethyl methyl ketone Butanone 3. Diethyl ketone 3-pentanone (or) pentan-3-one 4. Methyl n-propyl ketone Pentan-2-one 5. DiIsopropyl ketone 2,4-dimethyl pentan-3-one CLASS EXERCISE : 1] The formula of saturated aliphatic aldehyde is a) C3H7O b) C4H8O c) C4H7O d) C3H5O 2] The general formula of carbonyl compounds is a) CnH2n + 1OH b) CnH2nO c) CnH2nO2 d) CnH2n+1 O
3] The IUPAC name of α-methyl butyraldehyde is a) 3-methyl butane b) 2-methyl butanal c) 3-methyl butanal d) 1-methyl butanal 4] The IUPAC name of, , is a) 2-ethyl-3-methy pentanal b) 4-methyl hexanal c) 4-methyl-3-hexanal d) 2, 3-diethyl-butanal HOME EXERCISE : 1] The IUPAC name of, H5C2 CO CH3 is a) ethyl methyl hexanone b) 2-ethyl-3-methyl hexanone c) 4-ethyl-2-methyl-3-hexanone d) 3-ethyl-5-methyl-4-Heptanone 2] The C-atom in carbonyl group exhibit a) sp-hybridization b) sp2-hybridization c) sp3 −hybridization d) both (a) and (c) 3] Which of the following is not an unsymmetrical ketone? a) 2-butanone b) 2-pentanone c) 3-pentanone d) 2-hexanone EXAMPLES: 1] Name the geminaldihalide from which formaldehyde can be prepared. a) Methylene chloride b) Ethylidene dichloride c) 2, 2-dichloropropane d) 1, 1-dichloropropane 2] Which of the following compounds will give an aldehyde on oxidation? a) 2-methyl propane b) 2-propanol c) 1-propanol d) 2-propanone 3] Acetone can be prepared from 2-propanol by a) hydrolysis b) oxidation c) decarboxylation d) reduction 4] 1,1-dichloroethane when boiled with aqueous NaOH gives a) formaldehyde b) acetaldehyde c) acetone d) formic acid 5] Ethyl methyl ketone on reduction with zinc amalgam and conc. HCl gives a) sec. alcohol b) primary alcohol c) isobutane d) n-butane. 6] The chemical reaction of acetaldehyde and ammonia gives a) Ethylamine b) Hexamethylene tetra amine c) Acetic acid d) Acetaldehyde ammonia. 7] Among the following, the least reactive aldehyde is a) HCHO b) C6H5CHO c) CH3CHO d) C2H5CHO 8] RCH = O + H2 → RCH2OH. For this reaction, catalyst is a) Ni only b) Pd only c) Pt only d) Any of the above. 9] Aldehydes having no α-hydrogen atom undergo a) Hoffman reaction b) Aldol condensation c) Cannizzaro reaction d) Wurtz reaction 10] Acetone on treatment with sodium and ethanol gives a) acetic acid b) propanol c) 1-propanol d) isopropyl alcohol 11] Propionaldehyde is obtained by the alkaline hydrolysis of a) 1, 1-dichloroethane b) 1, 1-dichloropropane c) 2, 2-dichloropropane d) 1, 1-dichloromethane 12] Acetaldol is a) 3-hydroxy butanol b) 3-hydroxy butanal c) 2-hydroxy propanal d) 3-hydroxy pentanal H C CH CH C H CHO 5 2 2 5 CH3 C H2 5 CH C H2 5 CH
13] Paraldehyde would be : a) (HCHO)6 b) (CH3CHO)3 c) (HCHO)3 d) (CH3CHO)3 14] If acetaldehyde is treated with Benedict or Fehling solution, the following change occurs in the system: a) Ag+ Ag0 b) Cu2+ Cu0 c) Cu2+ Cu+ d) Na+ Na0 15] The compound that will not give iodoform on treatment with alkali and iodine is : a) acetone b) ethanol c) diethyl ketone d) isopropyl alcohol 16] Which of the following conversion can be brought about under Wolff-Kishner reduction? a) Benzaldehyde to benzyl alcohol b) Cyclohexanol to cyclohexane c) Cyclohexanone to cyclohexanol d) Benzophenone to diphenyl methane 17] What is not true about the oxidation of mixed ketones? a) They are resistant to mild oxidation b) Oxidation involves cleavage of bond between carbonyl carbon and -carbon atom. c) During cleavage carbonyl group remains with higher alkyl group. d) Oxidative cleavage is governed by Poppof's rule. 18] Which of the following represents Brady's reagent? a) [Cu(NH3 )4 ]SO4 b) KMnO4 /NaIO4 c) d) 19] CH3CHO X. The product X of the reaction is a) CO2 + H2O b) OHC __ CHO c) (COOH)2 d) (CH3 )2CO 20] In the reaction of NaBH4 with acrylic aldehyde a) Only CHO group is reduced b) Only C = C bond gets saturated c) Both ___CHO and C = C bond get reduced d) Neither C = 0, nor C = C bond is reduced 21] Propan-2-ol X Y In the above sequence of steps Y is a) Butan-2-ol b) Butan-1-ol c) 2-Methylpropene d) 2-Methylpropan-2-ol 22] Here, the final product Y is a) 3-Methylcyclopent-2-en-1-one b) 3-Methylcyclopentanol c) 2,5-Hexanediol d) 3-Methylcyclohexanone 23] A substance A containing three carbon atoms gives white crystalline precipitate with sodium bisulphite solution but does not give red precipitate with Fehling solution. A on treatment with NH2 __ NH2 / KOH will yield a) Propene b) Propane c) Cyclopropane d) Propionic acid 24] The reaction + CH3CO3H gives : a) an acid b) an ester c) an anhydride d) an alcohol 25] The reagent with which both acetaldehyde and ketone react easily is a) Fehling solution b) Grignard’s reagent c) Schiff’s reagent d) Tollen’s reagent → → → → NO2 O N2 NH-NH2 NH2 H N2 NH-NH2 oxidation SeO2 Mild Oxidation ( ) MeMgBr i ( ) H O ii 2 dil. O O CH3 −C−CH2 −CH2 −C−CH3 NaOH X heat Y O
26] Diethyl ketone and a dimethyl ketone can be distinguished with a) Tollen’s reagent b) Fehling’s solution c) Schiffs reagent d) Haloform test 27] Formaldehyde and formic acid are distinguished by treating with a) Tollen’s reagent b) NaHCO3 c) Fehling solution d) Schiff’s reagent 28] Benedict solution provides a) Ag+ b) Li+ c) Cu2+ d) Ba2+. 29] The class of compounds that are reduced in primary alcohols and respond to Fehling’s solution are known as a) aromatic amines b) aliphatic aldehydes c) aliphatic ketones d) aromatic ketones 30] One mole of an organic compound is found to require only 0.5 mole of oxygen to produce an acid. Which class of compound does the starting material belong to a) Alcohol b) Aldehyde c) Ether d) Ketone. 31] When acetaldehyde is heated with Fehling solution, it gives a precipitate of a) CuO b) Cu c) Cu2O d) Cu + CuO 32] Silver mirror test is given by a) aldehyde b) ketones c) amines d) ethers 33] Which of the following gives silver mirror test ? a) propanol b) propanone c) propane d) propanal 34] HCHO and CH3CHO differ from each other towards a) Schiff’s reagent b) Fehling solution c) ammonia d) ammonicalAgNO3 35] Tollens’ reagent is a) Cu(NO3 )2 + NH4OH b) AgNO3 + NH4OH c) sodium potassium tartarate d) (CH2 )6N4 + NH4OH 36] Aldehyde reacts with ammoniacal silver nitrate solution to give a) Ag2O b) [Ag[NH3 ]2 +] c) Ag d) Ag[NH] 37] The blue colour of Fehling’s solution is due to a) Cu2O b) CuCO3 c) CuO d) Cu+ + ions SESSION −2 AIM ✓ To discuss general methods of preparation of aldehyde and ketone. Methods of Preparation of Aldehydes and Ketones:- 1. From Alcohols:- a) By Oxidation:- [A] :1 o alcohols an oxidation with ag. Alkaline KMnO4, acidified K2Cr2O7 or CrO3/H2SO4[Jones reagent] gives aldehydes. RCH2OH + (O) K2 Cr2O7 / H+ → RCHO + H2O CH3CH2OH + (O) K2 Cr2O7 / H+ → CH3CHO + H2O CH3CH2CH2CH2OH + (O) K2 Cr2O7 / H+ → CH3CH2CH2CHO + H2O