1 / 44

Problem Set Assignments/2009

Delve into the world of organic chemistry covering topics like hydrocarbon covalent bonding, isomers, chiral centers, drug activity, and functional groups. Explore the complexities of geometric isomers, natural occurrences of trans fats, and organic nomenclature. Gain insights into organic molecules beyond carbon and hydrogen, classified by functional groups for a comprehensive understanding of their reactivity and function.

glanger
Download Presentation

Problem Set Assignments/2009

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Problem Set Assignments/2009 • May 12 class: Chapt 1 #1,2; Chapt 2#6,8,18; Chapt 3 #3; Chapt 5 #26,30; Chapt 9# 1,14; Chapt 12#1,18 • May 14 class: Chapt 6 #1,8; Chapt 8#1,21 • Answers posted on the course website

  2. What will be on quizzes and exam? • Lecture material and PP slides • Problem set material • Explanations etc. from Demo’s • Material covered in “What’s in the News” • Questions: T/F; short answer and multiple choice format

  3. 6. Organic Chemistry :an overview “carbon to candles” chapter 6

  4. HYDROCARBON COVALENT BONDING H H C H H ×H • •× × • •C• • × ×• • Hydrogen Atom Carbon Atom Carbon with Hydrogen • • • • • C : C • C : : C • • • • Carbon with Carbon C C C C C C triple single double

  5. ORGANIC STRUCTURES ( a ‘short hand’) H H H H-C-C-C-H CH3 – CH2 – CH2 or CH3 H H H-C-H H or CH3CH2CH2CH3 or all H’s understood

  6. Positional Isomers of the Alkanes # of C’sFormula# of Isomers 1 2 3 4 5 6 7 8 9 101520 CH4 C2H6 C3H8 C4H10 C5H12 C6H14 C7H16 C8H18 C9H20 C10H22 C15H32 C20H42 1 1 1 2 3 5 9 18 35 75 4347 366,319

  7. The First 10 Straight - Chain Alkanes NameMolecular Formula Methane Ethane Propane Butane Pentane Hexane Heptane Octane Nonane Decane CH4 CH3–CH3 CH3-CH2-CH3 CH3-CH2-CH2-CH3 CH3-CH2-CH2-CH2-CH3 CH3-CH2-CH2-CH2-CH2-CH3 CH3-CH2-CH2-CH2-CH2-CH2-CH3 CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH3 CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3 CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3

  8. More than 10 C’s in the chain • Undecane (11), dodecane (12) tridecane(13),tetradecane(14), pentadecane(15) hexadecane (16) heptadecane (17), octadecane (18), nonadecane(19) • After C19, beyond the scope of CHEM 1003! • C20H42 is eicosane

  9. Where to start numbering? • At the end of the chain with the most branches • 3-methylhexane

  10. Origin of Hydrocarbons

  11. Additional Complications! • Isomers!

  12. Optical isomers • Enantiomers: contain one chiral (Gr. “Chiros” =hand) center and are non-superimposable mirror images • Are identical in all respects except for the direction in which they rotate plane polarized light • D and L isomers • Arise from tetrahedral C with 4 different substituents

  13. Non-superimposable Mirror images

  14. Amino Acids and Chirality • All naturally occuring amino acids are the L –isomers : rotate the plane of polarized light in counterclockwise direction (Why??) • Enzymes: many are chiral and are only active for a specifically handed substrate • Lock and key (hand in glove) mechanism for activity

  15. Drug activity and handedness • L-Dopa is active vs. Parkinson’s disease • Its mirror image D-Dopa is inactive • “Chiral synthesis” of pharmaceuticals is a multibillion $ operation • Separations are costly and time consuming

  16. Isomers with multiple (n) unique chiral centres • # of isomers possible =2n. • These are diastereomers: have different mp, bp • Cholesterol has 8 chiral centres, hence 28= 256 possible isomers. But only one occurs naturally!

  17. Cholesterol : A steroid • 8 chiral centres

  18. Geometrical Isomers • Geometrical isomers • Simplest examples are cis-trans isomers • Differ only in the spatial arrangement of atoms

  19. Trans fats geometrical isomers of cis fats (cis=same) , trans= opposite

  20. Trans fats • Produced by partial hydrogenation of polyunsaturated vegetable oil • Are solids-give longer shelf life to products • Are worse than lard (sat’d fat) for your arteries! • “Banned” in NYC as of Jan 1, 2008

  21. Can we totally rid our diet of trans fats? • No, they occur naturally in small amounts in beef tallow, butter, milk • Arise from microbial hydrogenation of polyunsaturated fats in the animals’ digestive system • Ottawa City council has decided against a “ban” (wisely)

  22. Organic Nomenclature - Descriptors R C C C C R R R Examples cis- or trans- fatty acids trans cis R PABA = para-amino benzoic acid (in sunscreen) R R R R R ortho- meta- para- hexane butane pentane cyclo = cyclo

  23. More Complex Organic Molecules • Contain atoms other than C and H • To understand their properties, they are grouped according to the nature of these atoms and how they are bonded • Classified according to reactivity and function, hence “functional groups”

  24. Organic Functional Groups Functnl GrpGeneric‘Suffix’‘Prefix’Examples halocarbon -halide halo- PVC, R – X R – OH R – OR R – NHR perchloro- ethylene alcohol -ol hydroxy menthol, ethanol cholesterol ether -ether alkoxy Methyl-t-butyl ether (MTBE); octane enhancer amineam(ine)amino- adrenaline nicotine cocaine

  25. Organic Functional Groups Functnl GrpGeneric‘Suffix’‘Prefix’Examples R – C = O aldehyde -al acyl citronellal retinal formaldehyde H R – C = O ketone -one ----- cortisone acetone testosterone R

  26. Organic Functional Groups Functnl GrpGeneric‘Suffix’‘Prefix’Examples R – C = O carboxylic -oic carboxyl acetic acid acid ASA OH fatty acids R – C = O ester -oate ------ phthalates (acid + polyester OR alcohol) ethyl acetate R – C = O amide -amide amido- DEET (acid+ NR2

  27. Common Names vs. IUPAC • Acetone (common solvent) is propanone • Acetic acid (in vinegar) is ethanoic acid • Benzene (potent carcinogen) is 1,3,5-cyclohexatriene • Chloroform is trichloromethane

  28. Candle Chemistry • Candle waxes are mixtures of solid saturated hydrocarbons (paraffins) and long chain (C16 or more) monoesters. • Combustion in air generates CO2, H2O, heat and light

  29. Wax Components (esters) • Oleo Stearin or Oleo Stearate (palm vegetable wax) mp 155-160oF • Stearic acid is the common name for octadecanoic acid (C18) • Oleic acid is same as stearic acid, except for a cis C=C at the C9 position of the chain

  30. Dripless candles • Made by “overdipping” a normal candle (wax mp. 135-145 F) with a higher melting (160-170 F) • Candle burns down the middle leaving a hallow rim/tube to hold the melted inner wax • Or, try soaking a normal candle for 24 hours in salt water (2 tbs. salt to 2 cups water) for 24 hours • Demo!!

  31. Salted candles don’t drip! • Compare flame intensity

  32. Why does salt make a candle burn brighter? • Wick absorbs the NaCl solution • When the wax starts to burn, it excites the sodium electrons to a higher energy level • Visible light (yellow) is given off when these electrons return to a lower E level • Sodium D line at 589 nm (yellow) in visible range of 700 (red) to 400 (violet);3p to 3s

  33. Sodium D line • Heat excites 2p electrons to 3p level • Visible light (589 nm wavelength) is emitted when these electrons come down to the 3s level • Recall electron configurations • Na is 1s2, 2s2, 2p6, 3s1. • Na+ has lost the 3s electron

  34. Visible light • Red is longest wavelength, violet is shortest

  35. Why no drips? • Flame is hotter and stronger with salt present in the wick, hence melted wax on top vaporizes and burns off before it drips down the side!

More Related