WAS eae ae aatten ns, List introduced by Berzclius. Organic compounds having same molecular mula but differing from each other in some physical or chemical properties or both are known isomers (Greek : iso-same; meros - part) and the phenomenon is known as isomerism. merism is exhibited by compounds having directional bonds. . Jere are two main types of isomerism: structural isomerism and stereo isomerism. Isomerism et Constitutional Stereo isomerism (or) Structural Isomerism | a 1. Chain, Conformational Configurational 2. Position, Isomerism Isomerism 3. Functional, 4. Ring chain, 5. Metamerism and 6. Tautomerism. Geometrical Optical ©) isomerism Cis-trans jomerism can be of two types. structural isomerism (or) constitutional isomerism stereo isomerism (or) space isomerism STRUCTURAL ISOMERISM jis happens due to the difference in the structure of the compounds. In these compounds, the atoms ‘groups are linked to one another within the molecule, without any reference to the space. Structural omerism is further classified into different types Structural Isomerism | J J uy i) I L Chain (or), Position Ring chain Functional Metamerism —Tautomerism nuclear (or) isomerism isomerism isomerism, eleton isomerism Mase eau ct i Lge 85]SE eee (or) Nuclear (or) Skeleton isomerism : This type of isomerism is due to the difference in the nature of the carbon chain i. straight or chain of carbon atoms. Here, functional group, class of the compound (open (or) cyclic) rp, unchanged. The compounds are known as chain isomers. C,H, - butane a) CH, -CH, —CH,-CH, — n-butane (straight carbon chain) b) CH,-CH-CH, + __ isobutane (branched carbon chainy | (2-methylpropane) CH, C.H,, ~ pentane a) CH, - CH, ~ CH, - CH, ~ CH, > n- pentane (straight carbon chain) Dyn CHa ce, =CH,—CH, > isopentane (2- methylbutane) » a iy cH, 1 ie CH. =C—CH. —> _ neopentane (2,2 - dimethylpropane) 1 et cn, The number of possible isomers of a given formula increases rapidly with the increase of the n of carbon atoms. Position Isomerism : It is due to the difference in the positions occupied by the particular atom or group (substituents) same carbon chain or due to different positions of double or triple bonds in alkenes and alkynes. compounds are known as position isomers.Tui eer ee ee C,H, Cl (chloro pentane) : a) OH He Cie Crag CH? 2- chloropentane cl b) CH, ~CH, - ce —CH,-CH,-» — 3-chloropentane cl CHO : a) CH, -CH,- CH, - OH propan - 1 - ol (n- propylalcohol) CH. b) 2S CH OH > propan - 2 - ol (Isopropylalcohol) CH, ii) C,H, (Butene) a) CH,-CH,-CH=CH, > But - 1 - ene b) CH,-CH=CH-CH, > But - 2 - ene & Ring - chain Isomerism : either closed chain or open chain structures. The compounds are known as ring chain isomers. cH, 1H, - CH = CH, — Propene a Ne Cyclopropane - cH, H,C—CH, ie 1H, - CH, - CH = CH, —> But-1- ene I é H,C—CH, 2» H,C——CH, Note : It can be included in functional isomerism, if ring chain isomerism is not mentioned. ity Education Management Pvt. Ltd. is type of isomerism is due to different modes of linking of carbon atoms i.e. the isomers possess Cyclobutane Methyleyclopropane CH, ie H.C CH, Oe | HIG EG CHS /C - CH, - CH, = CH,- CH = CH, > Hex -I- ene H,C fie? | | cH, H.C ——CH, Cyclohexane Methyleyclopentane1 iseonne eisinn CHEMISTRY- C2 PART 5 rnpleenic 0 This is due to the difference in the nature of functional groups in the molecules. The compounds Known as funetional isomers CHO a) CH, - Ch, - OH (aleohol) CHO, a) CH, - COOH (ethanoic acid) CH,-CH ~CHO t OH 2~ hydroxypropanal 0 ©) CH,-CH, -C-OH propanoic acid ca, a) CH,-CH,-C=CH But - | - yne a) CH,CN Methyleyanide C,H.NO, : ° 4 a) C,H,-N Oo Nitroethane FUNCTIONAL ISOMERISM 0) ii) Aldehydes, Ketones, Unsaturated alcohols, Ethers and other Cyclic compounds i) Alcohols and Ethers (C,H. aa CH, - O- CH, (ether) HCOOCH, (ester) (methylformate) oO CH,-C-CH, -OH 1 - hydroxypropan - 2 - one methyl acetate CH, = CH — CH = CH, Buta - 1,3 - diene CH,NC Methylisocyanide C)H;-O-N=0 Ethylnitrite ete. (C,H.0 LEIS PanaISTRY- C2 PART - ) Acids, Esters and Hydroxy carbonyl compounds... ete. (C,H,,O,) ) Alkynes, Alkadienes and cycloalkenes (Ck Cyanides and Isocyanides (~ CN and — NC) ) Nitro alkanes and Akyl nitrites (-NO, and -O = N =O) i) Amines (Prima condary and Tertiary) ii) Alcohols, Phenols and Ethers ) Oximes and Amides is due to the presence of different alkyl groups attached to the same functional group or atom jc. -O-, -NH-,-CO-), he compounds are known as metamers, This phenomenon is known as metamerism. CHO a) CH,- O-C.H, b) CH, - 0 ~ CH,~ CH, CH, Diethylether Methylpropylether | CHS a) CH,-S- CH, b) CH, ~ S —CH,~CH,~ CH, Diethylthioether Methylpropylthioether CH,,0 oO o " tl a) C,H.-C-C\H, b) CH,-C-CH,-CH,-CH, Pentanone - 3 Pentanone - 2 Vv) CH,,N: a) CH, - NH - C,H, b) CH, - NH - CH, - CH, - CH, Diethylamine Methylpropylamine y) CH,N: es Zols a) GH,-N. 1) Cie cu, CH, Dimethylpropylamine Diethylmethylamine vi) CH,N: a) CH, - NH- CH, b) CH, - NH- C,H, Dipropylamine EthylbutylamineOa CHEMISTRY- C2 PART Phang ae \ | » CH, =C-H keto form enol form (en + ol) (Acetaldehyde) (Vinyl alcohol) 100% neglegible amount iS 2 On es | i) CH,-C-cH, => CH, =C=GCH, (keto form, 100%) (enol form, neglegible amount) Acetone prop -1-en - 2-ol 9 LAAs eee Cua ~ JI “ LW 6 fi ySS\ Zoe Users ae Peet Me: For simple aldetiydes andiceto form if table becuse ed Core OF YC =O (~364KI/ mol) more than that of C = C bond energy (250 Ki/mol) sat Cyclohexanone Cyclohex - 1 -en- 1 - ol (Ketoform, 99%) (Enolicform, 1%) gi OH ) CH,—C-CH, -COOC,H, = CH, G=CH_COOCH, Acetoaceticester (or) Ethyl aceto acetate enol form (Keto form) a o OHO CH,-C~CH, ~C-CH, ; 5 — CH, -C =CH-C-CH, Acetylacetone (Keto form) enol form - | Oo 1 OH fam sion - -CH,-N. — CH,-C=N. ) CH,-CH, SS — Se | Nitro form Enol form (Acinitroform) | Keto form Enol form. i aa Ve pa == \ =o Ney zs Enol form Keto formCSE Aaa ss i ou b 3 FS oe = ; ix) 0 0 HC oe 4 Keto form Enol form ° on Il | | —_. 2S | x) A a | S oO So Keto form Enol form The percentage of enol content increasing order : Aldehyde (MeCHO) < Ketone (MeCOMe) prananone 23 — pentanone c)2~—methyl pentane d) 3 ~methyl pentane IIL” Assertion and Reason type questions 2) Both A and R are true and R is the correct explanation of A \ _b) Both A and R true and R is not the correct explanation of A > )Ais true but R is false 4% d) Ais false but R is true 10. ie (A) : Both ethyl aleohol and dimethyl ether are structural isomers (1D Reason (R) : The above two compounds having the same molecular formula but differ in chemical properties. 11._ Assertion (A) : 2 ~ chloropentane and 3 ~ chloropentane are positional isomers (?) Reason (R) : The above two compounds are having different molecular formulaAssertion (A) : Propene and Cyclopropane are having same chemical properties ou { zason (R) : Both i ge Propene and cyclopropane are having same molecular formula y— ° Ou ertion (A) + | assertion (A) : Compound CH, ~C— 1 = CH, =C-H belongs to triad system gf J Reason (R) Assertion (A) : Diethylthioether and meth, Reason (R) : Diethyl ether and methyl iatement type questions, ) All the statements A, B and C are correct c) A, B are correct and C is incorrect Statement A : Alcohols and ethers are functional isomers \— Statement B : But ~1—ene and But 2 statement C : Statement B : Octane having 28 chain isomers ‘Statement C ‘Statement A : In acetaldehyde keto form is more stable than the enol form Statement B : Cyclohexanone and cyclohex ~ | — en — | ~ ol belongs to triadsystern_ V Oo oO I Hl Statement C : CH, ~C-CH, Statement A: H-C=N =C©N-H belongs to triad system tatement B : Acetaldehyde and prop ~ 1 — en ~ 2 — ol belongs to diad system | ° ‘Statement C : Ce Match the following Column - 1 A) 1 — propanol, 2 ~ propanol B) n— pentane ©) Acids, esters D) Hexene, Cyclohexane A B Cc D > 3 4 2 i) te) 1 : 4 ation Management Pvt. Ltd —C-CH, = CH, =C-CH, : In compou i Pound 1, 3 migration is there, it is called triad system \yl propylthioether belongs to tautomers ay J ropylether belongs to metamers \ ~ b) All the statements A, B and C are incorrect d) A, Bare incorrect and C is correct [aj ~ene are positional isomers — ~ Butane and isobutane are chain isomers y— tatement A : Nitro ethane and EthyI nitrite are positional isomers td) ‘oth ethyl alcohol and dimethyl ether having different boiling points. Lele OH 1 oO i! 2 G=CHaN beat Column ~ 1 [= 1) 1) 3 chain isomers 2) Ring ~ chain isomersim 3) Positional isomers 4) Functional isomerism A B Aes D oie a: Tie tates yACaS eters 20. Column -1 Column ~ I CH, /Oolls 7. . GH;—N 2, 1) Functional isomers \ch; ‘cH; A) CH) —-N B) CH,—C-H.CH, 4% 2)Diad system e © H-C=N, C=N-H 2 3)Metamers D) CH,-CN, CH,NC \ 4) Tautomers AV GBs CG -D, As Bug e we, a) 3 4 1 2 bd) 3 2 1 4 °) 3 1 2 4 ons 4 2 1 ORANGE WORK SHI 1, 2-Methyl butane and 2, 2-dimethy! propane are mal 9) Chain isomers b)Position isomers. _c) Metamers ) Functional isomers 2. ~ n-Butane and isobutane are a pair of ; i 8 Chain isomers ) Position isomers c) Metamers 4) Functional isomers 3. Isomerism exhibited by methy] formate and acetic acid is oa a) Geometrical b) Stereo, c) Tautomerism Ab Functional 4. CH,COCH, and CH, = C(OH)CH, represent l a) Metamers b)Position isomers ef Keto-enoltautomers__d) Functional isomers 5. _ The isomerism exhibited due to the difference in the size of the alkyl groups attached to the same funetio group is Ua a)Tautomerism b) Stereo isomerism _efMetamerism 4) Optical isomersim 6. _ Diethylether and n-propyl methylether are es letamers b) Tautomers ) Functional isomers) Optical isomers 7. ~ Among the following, the pair that is not a pair of metamers is l a) CH,OCH,CH,CH, & CH,CH,OCH,CH, 9 CH,OCH,CH,CH, & CH,OCH,CH, 4 c) CH] /NHCH CH CH, & cH, CH NHCH,CH, 4) CH, COCH. CH, CH. &CH, |CH,COCH,CH, ! 8. Qne among the following pairs of compounds are not isomers 2 [ t) a) (CH,),CH-O-C,H, and CH(CH,),-O-C,H, _) CH,CH,CO,H and CH,CO,CH, 27 CH,COCH, and CH,CH,CH,OH d) CH,CH,NO, and NH,CH,COOH 9. Ethylacetate and methyl propionate are = [ a) Functional isomers —_b) Tautomers PMetamers d) Position isomers Varsity Education Management Pvt. LThe isomerism exhibited ty a) Metamerism Y "propyl Position “Methyl propanol are 5) Functional alcohol 4nd isopropyl alcohol is feu -Butanol and 2 ©) Functional d) Tautomerism 4) Position Pair of which isomers { d The alkane that yields wo jgome, ©) Metamers AS Chain Neopentane by Bini monobromo setae sg i oe The number of isomers of C4, ae bel HH, ,is aya 6é 1418 (MLNR) . a [ ) ‘A compound which is not isome, ; ee y a) -Propyl methyl ether b) I-Butangh od ethers nes 0 ©)2-Methyl-2-propanol_f Butanone ms in alkane forming isomers Ge ie : B 4 The total number of isomeri 9 se pe "sometc trimethyl benzenes is a lig: dl Assertion (A) : N-Ethyletha oe ae ! ssel :N-Ethyle ie ylethanamine and methyl n-propyl amine are a pair of metamers Cea Reason (R) : The two compou inds differ in functional groups Assertion (A) : The number of iso, Reason (R) : LIST - 1 ae meric amines possible for the formula C,HyNis four [JJ ry, Secondary and tertiary amines are functional isomers LIST - 2 Cel A) Dimethyl ether, ethyl alcohol 1) Position isomers B) Acetaldehyde, Acetone 2) Metamers C) 2-Pentanone, 3-Pentanone 3) Functional isomers D) n-Propyl alcohol, Isopropyl alcohol 4) Chain isomers . 5) Non isomers The correct match is A’ BP Grey MB SRC ED! a 5 33a 1 270) 43 58a oa OMe A ies. i ee es —e-d WORK SHEET 2 How many structural isomers could be obtained by replacing one hydrogen of propene with chlorine ? a)2 b)4 3 d)5 eta n-propyl amine and isopropyl amine are examples of” eel Position isomerism b) Chain isomerism ©) Tautomerism d) Geometrical isomerism Ortho, meta and para dichlorobenzenes are [ae a) Chain isomers PyPosition isomers _c) Functional isomers 4) Tautomers Primary, secondary and tertiary amines are a) Chain isomers b)Position isomers pf Functional isomers d) Tautomers sity Education Management Pvt. Ltdeas i] } 5. “Which pair of isomers given below are position isomers ? i a) Propanal and propanone b) 1° Butyl alcohol and Isobuty! alcohol il ! 283° Butyl alcohol and Isobuty! alcohol d) 2° Buty] alcohol and 3° Butyl alcohol 6. Which pair does not represent isomers ? a) CH,COOH and HCOOCH, b) CH,-CHO and CH,=CH-OH oC, —CHO and CH, -CO-CH, d) CH con ‘CH, and CH, —CH,-CHO