Solutions_Manual_for_Organic_Chemistry_6th_Ed 489

Solutions_Manual_for_Organic_Chemistry_6th_Ed 489 - acidic...

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20-33 Acetic acid derivatives aRe often used as a test of electronic effects of a se±es of substituents: they are fai²ly easiLy synthesized (oR aRe comMe²cially aVailable), and pK³ values aRe easi´y MeasuRed by tit²ation. Substituents on ca²bonµ2 of acetic acid can express only an inductive effect; no ²esonance eFect is Possible because the CH¶ is sp · hyb¸dized and no Pi ove²lap is possible¹ Two conclusions can be dRawn froº the given Pk» values¼ ½irst, all fouR substituents are electron¾ withdrawing because all four substituted acids a²e stronger t¿an acetIc acid¹ Second, the ºagnitude Of t¿e electronÀwit¿drawing efÁect incReases in t¿e o²de²Â ÃÄ < CL < ÅN < Nƶ¹ (Çt is alwaYs a saÁe assuºPtion t¿at nit²o is the st²ongest elect²onÈwiÉhd²awing grouP of aLL t¿e coÊon substËtuents¹) 20-34
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Unformatted text preview: acidic because of the adjacent carbonyL g²ouPÐ See paÑ (c)¹ (b) AscorbÒc acid, pÓ» 4.71, is alMost identical to t¿e aciditY of acetic acidÔ pK» 4Õ74Ö Ä ÃH " Æ Æ ÄÃCH¶ _ ×ene , Äà ÃØ ' diol I (c) The Mo²e acidic Ø wilL be the one t¿at, w¿en reºoVed, giVes t¿e Mo²e stable conjugate base¹ star heRe Ù-l Æ _ ± à } Ú ² Û { ³ 1´ Ü } ÝÆ ÃH ÝÆÝ ÃH Øà ÃÄ Øà ÞÆÞ Äà ÆÞ . . ± . . t . . ± . . t TßE Mo²e only two ²esonànce fáâã ! • • ± (d) În the sLightly basic PH of P¿ysiological fluid, ascorbic acid ± Ù » :-e resoäance fáåæ acidic '. Is pResent as t¿e conjugate base, ascorbate, whose structure can ± R ÃÄ be ²epresented by any of t¿e t¿ree resonance fáçæ on the Left 20-35 (a) Q r è CH¶ÆH \ CÃÃØ (e) o Ìi) CÃÃÄ CHà of Part (c)¹ CH¶CÃÃØ (b) (f é¿ i CH·CH¶ êCHCH¶ÆÄ ±8± (C) µ o (d) ëìCíîï (h) ð Cííñ òó CÃÃH (G) C ô Ø (k) o CÃÃØ...
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