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JEEMAIN.GURU, 6., , By oxidation of alkyl benzene :, , CH3, , COOH, , , (i) KMnO4/OH, (ii) H3O, , Alkyl group having no -H atom will not be oxidized to –COOH. Any alkyl group containing at least one -H, atom will be oxidized to –COOH. The product of oxidation will be benzoic acid., , H2C––CH2CH3, , COOH, , , (i) KMnO4/OH, (ii) H3O, , C(CH3)3, Neutral KMnO4, , No oxidation, , The order of benzoic acid formation by oxidation of alkyl benzene., Methyl benzene >1° alkyl benzene >2° alkyl benzene, , , Physical Proper t ie s of Carboxylic Acid :, These are polar substances and can form H-bonds with each other to form dimmer structures., , O -----H ––O, R, , R, O––H -----O, , , , Boiling Point : Due to dimeric structure, the effective molecular mass of the acid becomes double the actual, mass. Hence carboxylic acids have higher boiling points than alcohols of comparable molecular masses. Due to, hydrogen bonding carboxylic acid show appreciable solubility in water. Its solubility in water is greater than, alcohol because H-bonding strength is greater in carboxylic acid than alcohol., , , , Melting Point : Melting point of the carboxylic acid with even number of carbon atoms is higher than acid, with odd number of carbon atoms. Such effect is observed in first ten members of the homologous series. This, feature is based on the fact that in the carboxylic acids with even number of carbon atoms, the terminal methyl, group and carboxylic group are on the opposite sides of zig-zag carbon chain. Hence they fit better in the, crystal lattice resulting in stronger inter molecular forces on the other hands acids with odd number of carbon, atom have carboxyl and terminal methyl group on the same side of zig-zag carbon chain which result in poor, fitting in the crystal lattice. This causes a weak forces among molecules and result for the relatively lower, melting point., The melting point and boiling points are usually higher than those of aliphatic acid of comparable molecular, masses. This is due to planar structure of benzene ring in the acid which can pack closely in the crystal than, aliphatic acids.

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JEEMAIN.GURU, , , Chemical Proper t ie s of Carboxylic Acid :, , 1., , Acidity of carboxylic acid :, Acidity is relative case with which it loses a proton leaving behind the anion. Its acid strength depends upon the, difference in the stability of the acid and its anion., , , O, , O, , R, , R, , H, , ••, , OH, ••, , O, , O, , , R, , R, O, , OH, , O, , , , non-equivalent structures of, resonance hybrid, , equivalent structures of, resonance hybrid, , both acid and its anion are stabilized by resonance, stabilization is far greater for the anion than for acid, because anion gives two identical resonating structure., 2., , Effect of subst ituent s on Acidit y :, Any factor that stabilizes the anion more than it stabilizes the acid should increase the acidity and any factor, that makes the anion less stable should decrease the acidity of the carboxylic acid., (a), , An electron withdrawing substituents stabilizes the anion by dispersing the –ve charge and therefore, increases the acidity of carboxylic acid., , (b), , Electron releasing substituents intensify the –ve charge on the anion resulting in decrease of stability of, the carboxylate anion and therefore decreases the acidity of the acid., , Carboxylic acids are weak acids and their carboxylate ions are strong conjugate bases. They are slightly alkaline, due to the hydrolysis of carboxylate anion compared to other species. The order of acidity and basicity of, corresponding conjugate bases are as follow., Acidity––RCOOH > HOH > ROH > CH  CH > NH3 > RH, Basicity ––RCOO– < OH– < HC  C– < NH2– < R–, O, , , , R, , O, , , , R, O, , Acidity increase, , O, Acidity decrease, , The effect of various number of the substituent and their distance from the carboxylic group has been illustrated, with the help of following examples., (i), , The effect of number of the substituent is shown by the chloro substituted acetic acids. The acid strength, increases in the order given below :, ClCH 2 ––COOH < Cl 2 CHCOOH < Cl 3 CCOOH, The increase in the no. of chloro substituent on -carbon atom of acetic acid make the electron withdrawing, effect more pronounced and hence make carboxylate ion more stable., When electron releasing substituent is attached to the carboxylic group then acid strength decreases as, the electron releasing power increases., R, R, , , R  CH 2  COOH > R  CH  COOH  R  C  COOH, , R

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JEEMAIN.GURU, (ii), , The effect of nature of the substituent is illustrated by the various halo acetic acids. Their acid strength, follows the order :, ICH 2 –COOH < BrCH 2 COOH < ClCH 2 COOH < F CH 2 COOH, CH 3 –CH 2 –CH 2 –COOH < CH 2 = CH–CH 2 –COOH < NC–CH 2 –COOH, , , , , (sp2), (iii), , (sp), , Effect of the position of the substituent : The effect of the substituent decreases as its distance from, —COOH group increases., , Cl, , Cl, , CH3––CH––COOH, , >, ,  -chloro propanoic acid, electron withdrawing, effect more, , , CH2––CH2––COOH,  -chloro propanoic acid, electron withdrawing, effect less, , Or t ho Effect :, The ortho substituted benzoic acid (whether the substituent is electron withdrawing or releasing) is comparatively, stronger acid than the para and meta isomers. This effect is called ortho effect. It occurs due to the joint, operation of steric and intra molecular H-bonding where ever it takes chance to stabilize the carboxylate anion, due to nearness of the substituent. Groups like –OH, –Cl, –NO2 will cause more stabilization to anion due to, direct interaction through intra molecular H-bonding., , OH, , O, H, , H, O, , OH, O, , O, o-hydroxy benzoic acid, (Salicylic acid), , Carboxylate anion, , COOH, , COOH, , COOH, , OH, >, , >, OH, OH, , Order of acidic character, Reaction due to cleavage of ––O––H bond as acid, O, ––C––O––H, , (i), , Reaction with active metals [alkali and alkaline metal] :, , O, R–––––OH + Na, (ii), , O, R–––––ONa + H2 ( ), , Reaction with CaO :, 2R –COOH + CaO  (RCOO)2Ca + H2O, , intra molecular, H-bonding, stabilization

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JEEMAIN.GURU, Te st for HCOOH and CH 3 COOH, Te s t, (i), , HCOOH, , C H 3C O O H, , Tollen reagent, , Silver mirror, , –, , Fehling solution, , Cu 2O red, , –, , HgCl 2, , Hg 2 Cl 2, , –, , Corrosive sublimate, , Calomel, , –, , K 2 Cr 2 O 7, , Cr + 3, , –, , Na 2CO 3 + H 2, , CH 4, , CO 2 + H 2, , –, , Reducing character, Reducing agents -, , (ii), , Decarboxylation., 160 0 C, , (iii), , Heating at, , (iv), , Heating sodium, , COONa, , salts of acids, , COONa, , –, , , , at, , 360 0 C, ,  HCl, , COOH, + NaCl, COOH, 5., , Conc.H 2 SO 4, , CO + H 2 O, , Dissolve, , 6., , P 2O 5, , –, , Anhydride, , 7., , Cl2 / P, , CO 2 + 2HCl, , Products are mono, di,, tri chloro acetic acid., , 8., , , , , , Ca salt heat, , H CH O, , CH 3 COCH 3, , Use s of Formic Acid :, (i), , As an antiseptic, , (ii), , For preservation of fruits., , (iii), , For leather tanning., , (iv), , In dying wool and cotton fabrics., , (v), , As a coagulating agent for rubber., , (vi), , For hydrogenation of oil as Ni-formate., , Uses of Acetic Acid :, (i), , Vinegar (6 - 10% solution) used as table acid and manufacture of pickles., , (ii), , In the form of salts, it is used in medicine and paints., , (iii), , For manufacture of rubber from latex and casein from milk CH3COOH is used as coagulant., , (iv), , Al and Cr acetates are used as mordants., , (v), , In the manufacture of dyes and perfumes., , (vi), , As a solvent and laboratory reagent.

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JEEMAIN.GURU, ACID DERIVATIVES, , , Derivatives of Carboxylic Acid, The –OH of an acid can be replaced by –Cl, –OR, or –NH2 group to yield an acid chloride an ester or an amide., These compounds are called functional derivatives of acid and they all contain acyl group. The functional, derivatives are all readily converted into the acid by simple hydrolysis., O, R C, Acid, , O, R, , O, –OH, , OH , R C Z, +Z, Acid derivative, , is Acyl group and Z is nucleophile Cl  , CH 3 COO  , C 2 H 5 O  , NH 2, , C, , etc., , O, –OH, +X, , R, , Acyl halide, X, O, , –OH, , O, , +NH2, , R, , Amide, NH2, , R, , O, , OH, , –OH, + OR, , Ester, , R, OR, , –OH, –RCOO, , O, , R, O, , , , R, , Anhydride, , O, , Characterist ic react ion for acid derivat ive s is nucleoph i lic subst itut ion react ion :, Mechanism :, , .., O:, .., , O, CH3, , .., C + Nu  CH3 C, Z, , O, Nu CH3 C, , Nu + Z, , Z, , sp2 hybrid C - atom, , sp3 hybrid C - atom, , In this reaction Z is leaving group. Weak bases are good leaving groups., Reactivity order - depends on the basic Character of Z, basicity : Cl – < CH 3 COO – < C 2 H 5 O – < NH 2–, –, In the given groups Cl is the weakest base so it is best leaving group., , , React ivi lt y order : CH 3 COCl > CH 3 COOCOCH 3 > CH 2 COOC 2 H 5 > CH 3 CONH 2, –, –, In acid derivatives the carbonyl group > C O is attached to highly electronegative Cl , CH3COO , NH2– etc., group due to electron withdrawing effect of these groups, the electron density on the carbonyl carbon is,  , , reduced further. Thus acetyl group is readily attacked by Nu shows nucleophilic substitution reaction., , , Basicit y of leav i ng groups :, Weaker the basic character of the leaving group more will be the ease with which the leaving group leaves the, compound and hence more is the reactivity Cl– ion being weakest base are most reactive leaving group., The order of basicity of the leaving group and their leaving tendency follows the order.

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JEEMAIN.GURU, 4., , Chemical Proper t ie s :, Acid anhydride are good acylating agents. Their reactions are less vigorous than the corresponding acyl halides., , O, ROH, , O, , R––C––OR + R'––C––OR, O, , O, , NH3, , O, , O, , R––C––NH2 + R'––C––NH2, , R––C––O––C––R, , O, H2O, , O, , R––C––OH + R'––C––OH, , hydrolysis, , O, , , OH/H2O, , O, , , , , R––C––O + R'––C––O, , ESTERS (RCOOR), Ester are the derivative of the carboxylic acid in which the –OH part of the carboxylic group has been replaced, by –OR group where R may be alkyl or aryl group., , , Met ho d of Preparat ion :, By reaction of acids wth alcohol or diazomethane in presence of ether., , , H / H2 O, , ,  R––COOC 2H 5 + H 2 O, , RCOOH + C 2H 5OH, , ether, R––COOH + CH2N2  RC O O CH 3  N 2, , Ester, , O, , O, , R––C––Cl + C2H5OH, , C5H5N, , R––C––OC2H5 + HCl, , O, R––C––O, , O, C H N, , O + C2H5OH, , 5 5, ,  R––C––OR' + R––COOH, , 2, , , , Chemical Proper t ie s :, , 1., , Conversion to other e sters :, , Transesterifications, , O, , O, , , R––C––OR' + R"––OH, , 2., , H, , R––C––OR" + R'––OH, , Conversion to amides :, , O, , R", , R––C––OR' + HN, , O, , R", , R––C––N, R", , + R'––OH, R"

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JEEMAIN.GURU, O, CH3OH, , 5., , A ; A is ?, , O, , CH2—CH2, (A), Sol., , OH, , CH2—CH2, (B), , COOCH3, , COOH OCH3, , (C) both are correct, , (A), , O, , O, This bond breaks hence intermediate is, , O, 6., , (D) None is correct, , , , O, OCH3, , CH3OH, , O, , OH, , , , End product of the following sequence of reaction is :, , O, (i) I2+ NaOH, , , C—CH3, , (ii) H, , , O, O, , (A) Yellow ppt. of CHI 3,, , O, , COOH, , (B) Yellow ppt. of CHI 3,, , O, (C) Yellow ppt. of CHI 3 ,, Sol., , (D) Yellow ppt. of CHI 3,, , CHO, , COOH, COOH, , (C), O, , Intermediate is, COOH, , 7., , ; which loses CO 2 on heating (-keto acid), , The final product obtained in the reaction :, , , Br2 / OH, CH 2 =CHCH 2 CH 2 CO 2 H , , , (A) BrCH 2 — CH—CH 2 CH 2 CO 2 H, , (B) HOCH 2 —CH 2 CH 2 CH 2 CO 2 H, , OH, (C) BrCH2—, , C=O, O, , (D), O, , C=O, , Sol., , (C), , 8., , On subjecting mesityl oxide to the iodoform reaction, one of the products is the sodium salt of an organic, acid. Which acid is obtained ?, , Sol., , (A) (CH 3 ) 2 C=CH—CH 2 COOH, , (B) (CH 3 ) 2 CH—COOH, , (C) (CH 3 ) 2 C=CH—COOH, , (D) (CH 3 ) 2 C=CH—CO—COOH, , (C)