CHM1022 Week 5/Lecture 1: Ketones and Aldehydes PDF

Week 5/Lecture 1: Ketones and aldehydes Weekly objectives 1. Identify the carbonyl group in chemical structures and name the functional groups 2. Understand that primary and secondary alcohols can be oxidised to aldehydes or ketones 3. Describe the structure and bonding in aldehydes and ketones...

Week 5/Lecture 1: Ketones and aldehydes Weekly objectives 1. Identify the carbonyl group in chemical structures and name the functional groups 2. Understand that primary and secondary alcohols can be oxidised to aldehydes or ketones 3. Describe the structure and bonding in aldehydes and ketones and how this relates to 3D structure 4. Understand that nucleophiles add to carbonyl groups  Carbonyls: Week 5, ketones and aldehydes. O C O H C H 3C CH3 HO O H 3C aldehydes ketones O O C C Class of Carbonyl R H R R 1-carbon group (R) 2-carbon group (R) 1-hydrogen (H) http://molview.org/?cid=1183 http://molview.org/?cid=180  Carbonyls: Week 6, acids and derivatives. O CH3 C H 3C O O H N C C C OH H 3C O CH3 O CH3 N H n carboxylic acids esters amides O O O C C C Class of Carbonyl R OH R OR R NH 2 1-carbon group (R) 1-carbon group (R) 1-carbon group (R) 1-hydroxyl (OH) 1-ether (OR) 1-amine (N)  Carbonyls from alcohols Note: “R” indicates a OH hydrocarbon or hydrogen. R R H alcohol OXIDATION WEEK 1: Alkenes O O O R R R HO OXn H R carboxylic aldehyde acid ketone ADDITION ADDITION OH OH WEEK 5: Carbonyls WEEK 6: Esters and Amides R R R R H R alcohol alcohol Carbonyls from alcohols. H O O O [Oxidant] [Oxidant] H R1 HO R1 H R1 H 1° alcohol aldehyde carboxylic acid H O O [Oxidant] R1 R2 R1 R2 H 2° alcohol ketone H O Oxidants [Oxidant] There are many. R1 R2 R3 These are beyond the scope of this course. 3° alcohol  Individual ACTIVITY 1: Identify the functional groups. 1. Identify the ketones, aldehydes and alcohols. 2. Label the alcohols as primary, secondary or tertiary. 10 mins OH H 3C CH3 CH3 O H a) b) c) H d) CH3 O H N CH3 CH3 O HO O OH H CH3 O e) OH f) g) HO H HO OH H 3C OH O CH3 OH CH3  Individual ACTIVITY 1: Discussion and feedback 1. Identify the ketones, aldehydes and alcohols. 2. Label the alcohols as primary, secondary or tertiary. 10 mins o 1 OH H 3C CH3 CH3 O H a) b) c) H d) CH3 O H N CH3 CH3 O HO 2o O 1o 2o OH H 2o CH3 O e) OH f) g) HO H HO OH H 3C OH O CH3 OH 3o CH3 3o 2o 2o ACTIVITY 2: Oxidation of alcohols in the field OH O O K2Cr2O7/H and [Cr(OH)6]3 {Cr[6+]} CH3 HO CH3 H CH3 {Cr[3+]} ethanol http://www.abc.net.au/archives/80days/stories/2012/01/19/3411491.htm  Individual ACTIVITY 3: Reaction products. What product(s) may form in the following reaction? 5 mins. O O [oxidant] OH OH OH H A B C D  Summary Today we have: Introduced the different types of carbonyl groups. Discussed that alcohols can be oxidised into different carbonyl compounds. Considered the bonding and properties of the carbonyl group. Week 5/Lecture 2: Reactions of ketones and aldehydes Weekly objectives 1. Identify the carbonyl group in chemical structures and name the functional groups 2. Understand that primary and secondary alcohols can be oxidised to aldehydes or ketones 3. Describe the structure and bonding in aldehydes and ketones and how this relates to 3D structure 4. Understand that nucleophiles add to carbonyl groups Bonding and properties of the carbonyl group? p-bond between two p orbitals. H 3C δ C O δ H 3C s-bond between two sp2 orbitals. A carbonyl is a s-and p-bond double bond between an sp2 C and an sp2 O. It is a polar bond due to the difference in electronegativity between oxygen (3.44) and carbon (2.55). Nucleophilic addition to the carbonyl group. One of the most common reactions of the carbonyl involves addition of nucleophiles. R δ R R H Nuc Nuc O H O Nuc O δ R R R This alkoxide is not isolated. In a second step acid is normally added.  Individual ACTIVITY 4: Nucleophilic addition to carbonyl Central to MOST mechanisms is identifying the nucleophilic atom. All mechanistic arrows start here. 15 mins On the following molecules indicate the most nucleophilic atom. O H O N C O H Cl N CH3 H H H Electronegativity of common atoms  Individual ACTIVITY 5: Nucleophilic addition to carbonyl For the nucleophiles (1 and 2) shown, draw the mechanistic arrows, and intermediate formed by their addition to a ketone. 10 mins O O R R 1 ketone O H H O R R 2 ketone  Individual ACTIVITY 5: Discussion and feedback For the nucleophiles (1 and 2) shown, draw the mechanistic arrows, and intermediate formed by their addition to a ketone. 10 mins O O O R R O R R 1 O O H H H O R R O R R H 2 The most common nucleophile….the Grignard reagent. CH3 CH3 δ H 3C δ O H O δ Br H H 3C Grignard as a PhD student tried this reaction. It failed. Why do you think the reaction did not occur? The most common nucleophile….the Grignard reagent. This is the Grignard reagent. CH3 CH3 δ δ H 3C O H O δ H 3C MgBr H Mg metal H H 3C δ CH3 Br H OH In 1912 Victor Grignard H 3C was awarded the Nobel prize for this discovery. Grignard reagents add to carbonyls to give alcohols. H O O R1 MgBr H R2 then H3O R1 R2 H aldehydes 2° alcohol H O O R1 MgBr R3 R2 then H3O R1 R2 R3 ketones 3° alcohol  Grignard reagents can be used to make medicines. Also used in, for example, the synthesis of aliskiren, a multimillion dollar anti-hypertensive drug. H 3C CH3 H 3C CH3 O O H H δ Ni catalyst Cl O O steps H H MgBr H 3C CH3 O O CH3 CH3 H 3C CH3 H NH2 O O O O H CH3 CH3 N NH2 H H H HO H3C CH3 H 3C CH3 O CH3 O CH3  Summary Today we have: Introduced nucleophilic addition to carbonyls. Examined the chemistry of Grignard reagents.