organic chemistry for first year students, Slides of Organic Chemistry

Download organic chemistry for first year students and more Slides Organic Chemistry in PDF only on Docsity! INTRODUCTION LECTURER Mr NM Chauke QUALIFICATIONS 1. B.Sc. Chemistry and Physics (UL, RSA) 2. B.Sc. Hons Chemistry (UL, RSA) 3. M.Sc. Chemistry (UL, RSA) 4. Fellowship Holder (Nanjing Tech, China) 5. Ph.D. Chemistry (UJ, RSA) (Submitted) CONTACT DETAILS chaukenm@tut.ac.za CONSULTATIONS Place your Appointment via myTutor of teense ty 1 ee Faculty of Engineering and the Built Environment = Department of Chemical, Metallurgical and Materials Engineering We epawer people ee g and the Built Env al and Materials En REACTION WITH PCC Example 1: Oxidation of primary alcohols to aldehydes “9° * . Cy pce Cy a ee > Example 2: Oxidation of secondary alcohols to ketones a _Pcc BU ! ects HH REACTION MECHANISM ° H O H*-H 4 i 0. OH + Cr-O Cr-OH r “~~ OH > ¢2 4 ~ Ke 6 ~*o + 6 H + H3;0 Lf ee oe H “S0,H,0 H,0 Ln REACTION MECHANISM K,Cr,0, “Hs0.H0 S OH gC / | CH; crO; CS ol H,SO,.H,0 No Reaction Aldehyde and Ketones Oxidation of Aldehydes o allows aldehydes 4 CrO,, Ho" o Aw, o o Ht / Hh There are a wide variety of reagents which can cause the AH R” “R oxidation of aldehydes to carboxylic acids aldehyde etorme Oxidation ta carboxylic acids Addition of a molecule of water to the aldehyde followed by a second oxidation Aldehydes have a proton attached to the carbonyl carbon leads to the carboxylic acid: 7 which can be abstracted, allowing them to be easily yo "8 Mn oxidized to form carboxylic acids. The lack of this hydrogen, makes ketones generally inert to these oxidation conditions. aldehyde hydrate + Heo Nevertheless, ketones can be oxidized but only under Soon extreme conditions. + CrO, +H,0 Oo HO tl I ‘Cr—OH Cr-OH a>) etd bu —_ H H®,2 H ' ° I SH Weve OH Sof by = wy :B the base here can be water or the conjugate base of the acid Oxidation of Ketones = Since ketones do not have hydrogen atom attached — Peroxycarboxylic acids, such as meta- to their carbonyl, they are resistant to oxidation. chloroperoxybenzoic acid (mCPBA) Can Oxidise Ketones to Esters " Only very strong oxidizing agents such as potassium manganate(VII) (potassium . 7 mCPBA Yee permanganate) solution oxidize ketones. wank CHCl, « However, this type of powerful oxidation occurs with cleavage, breaking carbon-carbon bonds and forming two carboxylic acids. Cy mCPBA 1. KMnOy, Hp, CHCl oO C= NaOH | i i 2. HaQ HO OH = Because of this destructive nature this reaction is rarely used. LiAlH, or NaBH, OH H-C-H OH H-C-H OH _ —~> H-c-R" Ethanal O II CH;— C—H Lit [H— AIH3]" REDUCTION OF ALDEHYDES AND KETONES 0. H H Li* ot CH; — Lo H + AIH, | Ethanol OH sf 4+ AIH; +LIOH |