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oc:, , , , , , ISOMERISM, , Two or more than two compounds having the same molecular formula but different physical/chemical or, both properties are called isomers and the phenomenon Is called isomerism., , EOMEnEM, , Structural Isomerism Stereoisomerism, , , , CT T | T 1, Chain Position RingChain Functional Metamerism Tautomerism, , Configurational Conformational, , Geometrical Optical, 2.1 Structural Isomerism, , 2.1.1 Chain Isomerism (C.1.), , The compounds which have same molecular formula, same functional group but different arrangement of, carbon chain show chain isomerism., , , , , , , , , , Ex. CH;—CH,—CH,—CH, CH,—CH—CH,, CH,, Butane (4C) 2-Methy! propane (3C), Ex. CH,;— CH,—CH,—CH,—OH CH GH CH OH, CH,, 1-Butanol (4C) 2-Methyl-1-propanol (3C), . O, Methylcyclobutane Cyclopentane, , 2.1.2 Position Isomerism (P.I.), , The compounds which have same molecular formula, same functional group, same parent carbon chain but, different position of functional group or multiple bond or substituents, show position isomerism., , Ex. CH,=CH—CH,—CH, CH,—CH=CH—CH,, But-1-ene But-2-ene, Ex. = CH,—CH,—CH,—CH,—OH CH,—CH,—CH—CH,, 1H, 1-Butanol 2-Butanol, cl, Br, * A <a, Br, 1-Bromo-2-chlorocyclopropane 1-Bromo-1-chlorocyclopropane, , 29

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TENANT A a, Example of CI and PI :, , $ (i) C,H,, has three structural isomers :, , CH,—CH,— CH,— CH, —CH, CH,—CH,—CH—CH, CH,--C —CH,, CH,, Pentane 2-Methyl butane 2,2-Dimethylpropane, (ii) C,H,, has 5 structural isomers, (@) CH,CH,CH,CH,CH,CH, (v) CH,—CH,--CH,— ia CH,, CH,, , Hexane 2-Methyl pentane, , () = CH,—CH,—CH —CH,— CH, (d) CH,—-CH— a CH,, be CH, CH,, 3-Methyl pentane 2,3-Dimethyl butane, GH,, ©) W4.c—C—cH,—cH, © (a-b), (@-c), (a-d), (@-e) —> Chain Isomers, du, (b-d), (b-e), (c-d), (c-e), 2.2-Dimethyl butane . b-c, d-e — Position Isomers., (iii) CHC, has 4 isomers : Position of chlorine atom is different in all the structure, so these are Position, isomers,, a ‘, a H,C—CH,—CH—Cl b. H,C — CH, — CH,—Cl, 1,1-Dichloropropane 1,3-Dichloropropane, rs a, , a H.C —C—CH, 4. He ~cH—cn,, , a a, 2,2-Dichloropropane, Ex. How many structural isomers of C,H,, are possible ?, Ans. (9), , 1,2-Dichloropropane, , lj cH — CH CH CH ,—CH —CH>-CH, Heptane, J+ CH —CH~CH—CH > cH CH, 2-Methylhexane, , te, , cH,, 3.-—* CH. —-CH — CH east —CH—CH, 3-Methythexane, Cu,, CH,, , , , |, 4h CH GH CH CCH, 2,2-Dimethyl pentane, CH, , ae

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PM 2 \sore02 0001 antanceT\ ¥eM\e OOULE 3102 SOMERS OI THECRY PSS, , , , ALLER, , CH,, , g, , H — CH —C —CH,—CH 3.3-Dimethyipentane, , CH, cH, 6. CH.—CH —CH—CH—CH, 2 3-Dimethyipentane, CH, CH CH, , :, , .>— CH —CH —CH—CH, 2.4-Dimethyipentane, CH,—CH, , f——* CH, —CH,—CH —CH,—CH, 3-Ethyipentane, CH, , ;, * CH, CH —C—CH, 2.2.3-Trimethyfoutane, CH, CH, (Triptane), , , , 2.1.3 Ring chain isomerism (RCI), Same molecular formula but different mode of linking (open chain & closed chain) of carbon atoms., f(—— CH.—CH=CH, [open chain], , CH., , , , 1H., Li, & ai [closed chain or ring], , , , GOLDEN KEY POINTS fa, , e Alkenes with cycloalkane and alkynes and alkadienes with cycloalkenes show Ring-chain Isomerism., , e Ring-chain Isomers are also Functional Isomers but priority must be given to Ring-chain Isomers., , 2.1.4 Functional Isomerism, Same molecular formula but different functional groups., , Following compounds show Functional isomerism, as they have same molecular formula and different functional, , group., (i) Alcohol and Ether — CH,—CH,—OH = and CH;—O—CH,, (ii) Aldehydes and Ketones ———> Sy and CH,—C—CH,, ll, fe), , (iii) Acids and Ester —> Ghee oH and HOG— OG,, ° °O, {iv) Cyanide and Isocyanide ——> CH,;—CH,—CH,—CN and CH,—CH,—CH,—NC, , °, o, () Nitro and Nitrite — ENN and =CH,—CH,—-O—N=O

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—_—_— a, , (vi) 1°, 2°, 3° Amines, , , , es, () CH,--CH,—CH,—NH, (ii) CH;—NH—CH,—CH, (iii) CH,-N—CH,, (vii) Alcoholic and Phenolic compounds :, , , OH, CH,OH CH,, Coy and, , (viii) Alkyl halides do not show Functional isomerism., 2.1.5 Metamerism, , Same molecular formula,, , same polyvalent Functional group but different alkyl groups attached to polyvalent, Functional group., , Polyvalent Functional group [Which have more than one valency} are :, , i, —o—, -s-, 7c -—c-o-, —G-NH=, —NH-—, a Ng, —C—N-—, ll « » =e iol, ° oO oO ll oO, oO, Ex. CH,;—O—CH,—CH,—CH, #3 H,C-CH,-O-CH,-CH,, Ex. CH;—CH,—NH—CH,—CH, CH,—NH—CH;—CH,—CH,, Ex. CH;—NH—CH,—CH,—CH,—CH, H,C-CH,-NH-CH,-CH,-CH,, Ex. CH,~C— CH, — CH, CH, — CH, CH CH. C— CH,— CH, — CH,, oO, , O°, Examples Based on Structural Isomerism :, Ex. 1 C,H,,O Structural isomers =>7 [4 alcohol and 3 ethers], , total 7 structural isomers are possible., Alcohol : = CH,—CH,—CH,—CH,—OH, , CHS-CHe- CH CH,, , OH, t, CH CH —CH—OH and CH—¢—0H, CH, CH,, , Ethers : CH;—O—CH,—CH,—CH,, C,H,—O—CH,, CHO eH —cH,, , CH,, Ex. 2 Aromatic isomers of C,H,O., ie tC" " CH, o—cH, OH , :, (a) (b) () on @ ©, , IH, e ab — Functional isomers ‘ bc ~ Poettion omer, * od - Position isomers . aa ~ Functional a, °. ae — Functional isomers * ave, , ~ Functional isomers *, Note : Alcoholic and phenolic groups are Functional isomers. ., oO} :

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FT 2 eee son anratcen creates wereutes\c2 BOREREANOT THEORY NS, , , , 1. Structures CH,—CH,—CH= CH, and CH,— c=CH, are :~, CH,, , (1) Chain isomers (2) Position isomers, , (3) Beth chain & position isomers (4) Not isomers, 2. How many mentum carbons required for Chain isomertan and Position isomerism in alkanes ?, , 45 (2) 3.5 (3) 4, 6 (4) 4,47, 3. How many srénimurn carbons required for Chain isornerism and Position isomerism in alkenes ?, , 4.5 (2) 3.4 (3) 4, 4 (4) 5,5, 4. How merry rrénirrm carbons required for Chain isomerism and Position isomerism in allymes ?, , 1) 5.4 (2) 5.3 (3) 4, 6 (4) 4,4, 5. CH,—CH=CH—CH, and CH,—CH, are - ‘, , J |, CH,— CH, ,, (1) Ring-chain Isomers (2) Chain Isomers (3) Functional Isomers {4) Position Isomers, t i, 6. CH-CH—CH,—C—OH and CCH OH —C-H are, OH, , (1) Position isomers (2) Functional isomers (3) Identical (4) Chain isomers, 7. CHS—CH—CH, = and CH,—CH,—S—CH, are , (1) Ring-chain Isomers (2) Chain Isomers (3) Functional Isomers (4) Identical, , a ? i] I, , 8. CH—C—O—C—CH, and CH,—C—O—C—CH, are , (1) Metamers (2) Chain Isomers (3) Identical (4) Position Isomers, 2.2 Stereo isomerism, , Two or more than two compounds having same molecular formula, same structural formula but different, , arrangements of atoms or groups in space. :, (A) Configurational Isomerism : Stereo isomers which have following characteristics., , (a) Stereo isomer which cannot interconvert at room temperature due to restricted rotation known, , as Geometrical isomerism., , (b) Stereo isomers which have different behaviour towards plane polarised light are known as optical isomers., , (B) Conformational Isomerism, , 2.2.1 Geometrical isomerism (G. I) :, , (i) Alkenes (>C=C<), oximes (>C= N—) and azo compounds (—N==N—] etc., show G. I. due to restricted, rotation about double bond and (ti) cycloalkanes show G. I. due to restricted rotation about single bond, , in ring., _ G. I. IN ALKENES :, , . Reason : Restricted rotation about double bond :, , (Cpenmcemeermemmrrmmraieceransee gD, , 33