Classification & Nomenclature Solved Problems

Page # 11 CLASSIFICATION & NOMENCLATURE SOLVED PROBLEMS Ex.1 Sol. How many 1º carbon atom will be present in a simplest hydrocarbon having two 3º & one 2º carbon atom ? (A) 3 (B) 4 (C) 5 (D) 6 (Ans. B) CCCCC | | C C 2, 4 - dimethyl pentane is the compound having 2 – 3º carbon & 1 – 2º carbon atom & 4-1º carbon atoms. Ex.2 Sol. Ex.3 Sol. The formula CnH2n – 2 shows (A) Alkene & Alkyne (B) Alkyne & Alkadiyne (C) Alkane & Alkadiene (D) Alkyne & Alkadiene For Acetylene & Allene HC  CH CH2 = C = CH2 (C2H2) (C3H4) (Ans. D) In which of the following tert. carbon is absent (A) Iso octane (B) Triptane (C) Isopropyl amine (D) Isopentane (Ans. C) C | * Iso Octane C  C  C  C  C | | C C (1 – 3º carbon atom) Triptane * C  C | C Crotonic acid or (2 - Butenoic acid) The principal functional group is - COOH. Ex.5 Sol. Ex.6 Sol. (no tert. carbon atom) * Isopentane C  C  C  C  C | C (1 - tert. carbon atom) Ex.4 Sol. The type of unsaturation present in crotonic acid is (A) ,  (B)  ,  (C) ,  (D)  ,  (Ans. A) The type of unsaturation present in crotonic acid is ,  O   || CH3  CH  CH  C  OH 4 3 2 1 C3H6Br2 can shows (A) Two gem dibromide (B) Two vic dibromide (C) Two tert. dibromo alkane (D) Two sec. dibromo alkane 1, 1 - dibromo propane (Ans. A) Br | H3 C  C  CH3 | Br 2, 2 - dibromo propane (Two gem dibromides) Ex.7 Sol. Ex.8 (1 – 3º carbon atom) Isopropyl amine C  C  NH2 | C Example of a gem dihalide is : (A) Pentamethylene chloride (B) Ethylene chloride (C) Propylene chloride (D) Benzal chloride (Ans. D) The example of a gem dihalide is benzal chloride. In such a halide both Cl atoms are attached to the same carbon atom. Sol. The trivial name of the compound CH2 = CH – CN is (A) Vinyl cyanide (B) Cyano ethylene (C) Acrylonitrile (D) 2 - propene nitrile (Ans. C) 3C + (=)  Acryl group suffix of – CN group is onitrile. The structure of isopropyl carbinol is : (A) (CH3)2CHOH (B) CH3– CHOH – CH2 – CH3 (C) (CH3)2CH CH2OH (D) (CH3)3OH (Ans. C) In derived name system H | H  C  OH | H Carbinol H3 C  CH  CH3 | H  C  OH | H Isopropyl carbinol Ex.9 The IUPAC name of the following compound is CH3  CH2 | CH  CH2  CH3 | H3 C  CH  CH3 (A) 3 - isopropyl pentane (B) 2- methyl -3-ethyl pentane (C) 3 - ethyl -2-methyl pentane (D) 3 -ethyl -4-methyl pentane (Ans. C) Page # 12 CLASSIFICATION & NOMENCLATURE Sol. Select the l on gest cha in having more substitutes. Ex.10 The IUPAC name of the compound CH3CH = CHCH = CHC  CCH3 is (A) 4, 6–octadien-2-yne (B) 2, 4–octadien -6-yne (C) 2–octyn - 4, 6-diene (D) 6-octyn-2, 4-diene (Ans. B) Sol. Between double bond & triple bond double bond is preferred. Ex.11 The I.U.P.A.C. name of compound (CH3)3C.CH2CONH2 is : – (A) 1, 1,1- trimethyl propanamide (B) 3, 3, 3-trimethyl propanamide (C) 3, 3-dimethyl butanamide (D) 3-t-butyl propanamide (Ans. C) Sol. The I.U.P.A.C. name of compound (CH3)3C.CH2CONH2 is CH3 O | || CH3  C  CH2  C  NH2 4 3| 2 1 CH3 (3, 3-dimethyl butanamide) Sol. Ex.15 IUPAC name of carbonyl chloride is (A) Phosgene (B) Chloromethanoyl chloride (C) Dichloroketone (D) Dichloromethanone (Ans. B) Sol. IUPAC n ame of carbonyl chloride i s chloromethanoyl chloride. (Chloromethanoyl chloride) Principal functional group is O ||  C  Cl (-oyl-chloride) Its common name is phosgene and it is poisonous gas. Ex.16 The structure of 2- nitro-1-propanamine is NO 2 NH2 | | (A) CH2  CH2  CH2 O || The principal functional group is C  NH2 CH3 | (B) O  N  O  CH  CH2  NH2 (Amido) Ex.12 IUPAC name of four carbon 3º amine is (A) Dimethyl methane amine (B) N, N-dimethyl ethane amine (C) N-ethyl N-methyl methane amine (D) Butane amine (Ans. B) Sol. IUPAC name of four carbon 3º amine is N, N dimethyl ethane amine. CH3  CH2  N  CH3 | CH3 (N, N - dimethyl ethane amine) Ex.13 IUPAC name of compound CH3CH2OCOCH2CH2CH3 is (A) Propyl propanoate(B) Ethyl butanoate (C) Propyl butanoate (D) Ethyl propanoate (Ans.B) Sol. The IUPAC name of CH3CH2OCOCH2CH2CH3 is ethyl butanoate. 1 2 3 4 CH3  CH2  O  C  CH2  CH2  CH3 || O Ethyl Butanoate Ex.14 Trivial name of 2, 3- dihydroxy butanedioic acid is (A) Malic acid (B) Tartaric acid (C) Citric acid (D) Lactic acid (Ans. B) 1 Trivial name of 2,3 dihydroxy butandioic acid is tartaric acid. CH(OH). COOH | CH(OH) COOH (Tartaric acid) The principal functional group is – COOH group. NO 2 NH2 | | (C) CH3  CH  CH2 O  N  O CH3 | | (D) CH3  CH  CH2 Sol. (Ans. C) The N of nitro group will be attached from carbon chain so alternate 2nd & 4th are wrong in this way & the alternate 1st is 3-nitro-1propane amine. Ex.17 The IUPAC name of - CH3  CH  C  CH  OH | || | CH3 O CH3 (A) 4 - methyl -2-hydroxy-3- pentanone (B) 2-hydroxy -4- methyl-3- pentanone (C) both are correct (D) None (Ans. B) Sol. The principal group is C  & the alphabate H || O of hydroxy group comes first than M of methyl group. So numbering is done in the following way. Page # 13 CLASSIFICATION & NOMENCLATURE 4 3 2 CH3  CH  C  CH  OH | || | 5 CH3 O 1CH3 Ex.18 The IUPAC name for - CH2  C  CH  C  O | | | Br Cl H (A) 2-chloro-3- bromo-3-butenal (B)2-chloro-3-bromo-3-butene carbaldehyde (C) 3-bromo-2-chloro-3-butenal (D) 3-bromo-2-chloro-3-butenone (Ans. C) Sol. (A) 1,1-diformyl propanal (B) 3- formyl butanedial (C) 2-formyl butanedial (D) 1,1,3-ethane tricarbaldehyde (Ans. C) The IUPAC name of the given compound is 2-formyl butanedial, 2 - formyl butanedial The principal functional group is – CHO. Ex.20 The correct IUPAC name of compound is - Sol. (A) 2-cyano-3-oxopentanal (B) 2 - formyl-3-oxopentanenitrile (C) 2-cyano-1, 3-pentanedione (D) 1, 3-dioxo -2-cyanopentane (Ans. B) The correct I.U.P.A.C. name of n ame is Ex.22 I.U.P.A.C. name of : 4 3 2 1 CH2  C  CH  C  O | | | Br Cl H 3-bromo-2-chloro-3-butenal Ex.19 The correct IUPAC name of the following compound is - Sol. It ’s correct I.U.P.A.C. ethoxy - 1- amino propane. Sol. (A) Methyl-2,2 acetyl ethanoate (B) 2, 2 acetyl-1-methoxy ethanone (C) Methyl-2-acetyl-3-oxobutanoate (D) None (Ans. C) The I.U.P.A.C. name of the gi ven compound is Methyl-2-acetyl-3-oxobutanoate The principal functional group is ester group. Ex.23 The IUPAC name of  -ethoxy -- hydroxy propionic acid (trivial name) is (A) 1, 2-dihydroxy -1- oxo - 3- ethoxy propane (B) 1 -carboxy - 2- ethoxy ethanol (C) 3 -ethoxy - 2-hydroxy propanoic acid (D) All above (Ans. C) Sol. The compound -ethoxy --hydroxy propionic acid is 3-Ethoxy -2-hydroxy propanoic acid The principal functional group is - COOH. Ex.24 The IUPAC name of compound is : is 2-formyl -3- oxopentanenitrile Here the main functional group is -CN, which has nitrile suffix and CHO and CO are the side functional groups which are used as prefixes. Ex.21 All the following I.U.P.A.C. names are correct except (A) 1-chloro-1-ethoxy propane (B) 1-amino-1-ethoxypropane (C) 1-ethoxy-2-propanol (D) 1-ethoxy-1-propanamine (Ans. B) Sol. All the given I.U.P.A.C. names are correct except 1-amino-1-ethoxypropane 1 Sol. (A) 3,5-Dimethyl-4-Formyl pentanone (B) 1-Isopropyl-2-methyl-4-oxo butanal (C) 2-Isopropyl -3-methyl -4-oxo pentanal (D) None of the above (Ans. C) The IUPAC name of compound O 5 4|| 3 2 CH3–C–CH – CH – CH–CH3 | | | CH3 CHO CH3 is - Page # 14 CLASSIFICATION & NOMENCLATURE 2-Isopropyl -3-methyl -4-oxo pentanal In this compound the principal functional group is – CHO. Sol. Ex.25 The IUPAC name of compound is : - 4-carbon chain having 2-methyl groups. Ex.28 Which of the following is not correctly matched : (A) Lactic acid Sol. (A) 2-amino -3-chloro-2-methyl -2-pentenoic acid (B) 3-amino-4-chloro-2-methyl -2-pentenoic acid (C) 4-amino-3-chloro-2-methyl -2-pentenoic acid (D) All of the above (Ans. B) The IUPAC name of compound CH3–CH–COOH | OH (B) Tartaric acid (C) Pyvaldehyde CH3C(CH3)2CHO (D) Iso–octane (Ans. D) Sol. Iso–octane is - is 3-amino-4-chloro-2-methyl-2-pentenoic acid The principal functional group is carboxylic acid (–COOH). Ex.26 The IUPAC name of the structure is - (A) 3-amino-2-formyl butane-1, 4-dioic acid (B) 3-amino -2,3-dicarboxy propanal (C) 2-amino -3- formyl butane -1, 4-dioic acid (D) 1-amino -2-formyl succinic acid (Ans. C) Ex.29 Which of the following pairs have absence of carboxyclic ring in both compounds ? (A) Pyridine, Benzene (B) Benzene, Cyclohexane (C) Cyclohexane, Furane (D) Furane, Pyridine (Ans. D) Sol. Furane Pyridine Ex.30 Write the structural formula of the compound 3-methylbutanoic acid - Sol. Although CHO group is senior than NH2 but after deciding senior most group (COOH) next groups are preferred as alphabatically. So numbering is done from left to right. Prefix for NH2– group is amino and for CHO – group is formyl. Ex.27 How many carbons are in simplest alkyne having two side chains ? (A) 5 (B) 6 (C) 7 (D) 8 (Ans. B) (A) (B) (C) (D) (Ans. A) Sol. 3-methylbutanoic acid