lect33-apr23 - Chemistry 101-501 Spring 2010 Instructor:...

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Unformatted text preview: Chemistry 101-501 Spring 2010 Instructor: Dr. David P. Barondeau Office: Interdisciplinary Life Science Building Room 1196A Phone: 458-0735 E-mail: barondeau@tamu.edu (please put CHEM 101 in subject line) Lecture: MWF 9:10-10:00 Room 100 Heldenfels Office Hours: M 10:15 - 11:30 (Room 104A Heldenfels) W 10:15 - 11:30 (Room 104A Heldenfels) or by appointment Course Website: Blackboard Vista (http://elearning.tamu.edu/) Instructor Assistant: Jessica Garber jgarber@mail.chem.tamu.edu (Tues 7-9 Held 100) Supplemental Instructional Leader: Kathy Webb kmwebb2010@neo.tamu.edu 1 (Sun 9-10; Wed 7-8; Thurs 6-7 all in HRBB 15) Chemistry 101 • • • Homework problem set 7 has been assigned (due April 27th) Exam 4 will be on Friday April 30th (as originally scheduled) If you are having difficulty with the homework – – – Email: jgarber@mail.chem.tamu.edu (IA Jessica Garber) Email me at barondeau@tamu.edu My office hours • • M, W 10:15 to 11:00 (HELD 104A) T R 5-6:00 in ILSB room 1196A – TA Help desk HELD 116 SI Leader Kathy Webb kmwebb2010@neo.tamu.edu Sun 9-10; Wed 7-8; Thurs 6-7 all in HRBB 15 Instructional Assistant Jessica Garber jgarber@mail.chem.tamu.edu • Review sessions – – – Tues 7-9 HELD 100 2 3 Oxidation of alcohols • Primary alcohols – Oxidation to aldehyde • R-CH2-OH → R-CHO + 2H+ + 2e- – Oxidation to carboxylic acid • R-CHO + OH- → R-COOH + H+ + 2e- • Secondary alcohols – Oxidation to ketone • R2-CH-OH → R-CO-R + 2H+ + 2e- • Tertiary alcohols – No oxidation • Common oxidizing agents – KMnO4 – K2Cr2O7 Potassium permanganate Potassium dichromate 4 Aldehydes and ketones • Have pleasant odors and are often used in fragrances • Benzaldehyde is responsible for the odor of almonds and cherries • Cinnamaldehyde is found in the bark of the cinnamon tree • Naming – Aldehydes end with “-al” – Ketones end with “one” Cinnamaldehyde 5 Aldehydes and ketones 6 Aldehydes and ketones • Reduction of aldehyde to primary Reduction alcohol alcohol Reduction of ketone to secondary Reduction alcohol alcohol Common reducing agents – NaBH4 – LaAlH4 hydride hydride Sodium borohydride Sodium Lithium aluminum Lithium • • 7 Carboxylic acids Benzoic acid Acetic acid Acetic Acids are found in Acids many natural substances: bread, fruits, milk, wine fruits, Carboxylic acid group Carboxylic with acidic H+ with All are WEAK acids All WEAK 8 C a r boxyl i c Ca Aci ds Aci H O C O C O C H3 O Formic acid, Formic HCO2H, gives HCO H, the sting to ants the Aspirin, acetylsalicylic acid 9 Carboxylic acids 10 Carboxylic acids • Carboxylic acids can be reduced to aldehydes and then Carboxylic reduced further to primary alcohols reduced • Carboxylic acids can also react with alcohols to form esters 11 Esters Aci ds + Al cohol s --> EST ERS Ester s have gener al l y pl easant odor s 12 Aci ds + Al cohol s --> EST ERS Acetic acid 3-methylbutanol O H3C C O CH3 CH2 CH2CHCH3 3-methylbutylacetate Many fruits such as bananas Many and strawberries contain esters esters 13 Esters 14 Esters: hydrolysis • Esters can be hydrolyzed in the presence of a base (such as NaOH) 15 Esters: hydrolysis • Esters can be hydrolyzed in the presence of a base (such as NaOH) 16 Esters: hydrolysis 17 Esters: hydrolysis 18 Amides Aci ds + Ami nes --> AM I D ES Naming The N indicates that the The methyl group is bound to the nitrogen atom the The “acet” indicates the The acid on which the amide is based (acetic acid) is N-methylacetamide 19 Amides Aci ds + Ami nes --> AM I D ES H H H H C H H O C N C C C H C C C H H O Amide link Acetoaminophen Tylenol, Datril, Momentum, ... 20 Amides: nitrogen geometry • Carbon atom of amide linkage expected to be sp2 hybridized with bond angles of 120 degrees – Exactly what is observed in structure • Nitrogen atom is surrounded by four pairs of electrons – Predict N atom to have sp3 hybridization and bond angles of 109 degrees – Not what we observe – Nitrogen atom also has trigonal planar geometry with three bonds at 120 degrees – Second resonance form of amide 21 Functional group summary 22 ...
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