lect31-apr19 - 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 25th) 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 Alkenes • Naming alkenes – Names end in “-ene” – Root name is that of Root longest carbon chain that contains the double bond contains – Position of double bond is Position indicated by a number indicated – Cis and trans are added Cis when appropriate when H 1 C H 1-but ene 2 C 34 CH 2 CH 3 H 1 C H 2 C 3 CH 3 1 H 3C 2 C 3 C 4 CH 3 H 2 C 3 C 1 H3 C 4 CH 3 H CH 3 H H H 3 2-m ethyl propene (i sobut ene) cis-2-butene trans-2-bute ne Naming alkenes 4 Naming alkenes 5 Alkenes 6 Reactions of Alkenes: Addition reactions • Alkenes are unsaturated — more bonds can form to Alkenes unsaturated the C atoms the – Carbon atoms are capable of forming bonds to a maximum Carbon of 4 other atoms (such as in alkanes and cycloalkanes) of – In Alkenes the carbon atoms are bound to only three other In atoms atoms • Molecules such as Br2, H2, HCl, HBr, and H2O add to add the double bond the – Change the hybridization from sp2 to sp3 at the carbon atoms H C C + Br2 H H H Br Br HC CH HH 1,2-dibromoethane 7 Reactions of Alkenes: Addition reactions • Molecules such as Br2, H2, HCl, HBr, and H2O add to the double bond add H H C C + Br2 H H Br Br HC CH HH 1,2-dibromoethane 8 Alkenes • In the 1860s a Russian chemistry Vadimir In Markovnikov examined a large number of alkene addition reactions addition • When two isomeric products were possible, he found When that one product predominates that • Markovnikov’s rule: when a reagent HX adds to an alkene, the hydrogen atom becomes attached to the carbon that has the largest number of hydrogens carbon 9 Alkenes: addition reactions Fat placed in Fat Br2 vapor Br • The fat in bacon is partially unsaturated The The fat adds Br2 to the C=C bonds The • Fats can be “hydrogenated” with H2 10 Alkenes: addition reactions • Fats can be Fats “hydrogenated” with H2 “hydrogenated” – Hydrogenation of an oil Hydrogenation makes it less susceptible to spoilage spoilage – Also converts it from a liquid Also to a solid to Peanut butter has partially hydrogenated vegetable Peanut oil oil 11 Al kynes • Alkynes have carbon-carbon triple bonds Alkynes • C2H2: common name = acetylene systematic name = ethyne Preparation: CaC2(s) + H2O(liq) --> O(liq) C2H2 (g) + Ca(OH)2(s) ∆Hfo(C2H2, g) = +226.7 g) kJ/mol kJ/mol Combustion of acetylene produces a Combustion flame of over 3300 °C (6000 °F) 12 releasing 11.8 kJ/g releasing Ar oma ti c Compounds • Class of compounds Class have significant, and usually not unpleasant, odors odors n • Benzene, C6H6, iin the top 25 chemicals produced in the U.S. • Starting point for Starting hundreds of other compounds compounds 13 Resona nce i n Benzene • C6H6 has two resonance structures with alternating double bonds • The π electrons are delocalized over the ring The delocalized H H C H C H H C H C C H H H C C C H C C HC C H CH CH C H HC C H CH Resonance st ructures of benzene, C H6 6 Abbreviated representati on of resonance structure4 1s Resona nce i n Benzene • CC bond order is _______________ • C–C single bond = 154 pm C–C C=C bond = 134 pm C=C • CC bonds in benzene = 139 pm π electrons delocalized 15 Bondi ng i n Benzene 16 Other aromatic hydrocarbons Toluene • Originally isolated from the pleasant-smelling gum of a South American tree South • Used in cough syrups and perfumes perfumes Naphthalene • Ingredient in “moth balls” Ingredient 17 Other aromatic hydrocarbons Other TNT trinitrotoluene Saccharin Aspirin 18 C6H4CH3(NO2)3 Reactions of aromatics • Substi tuti ons — not additions — are typical CH3 + CH3Cl AlCl3 + HCl AlCl3 is a catalyst. Catalysts typically used in aromatic substitutions aromatic 19 Reactions of aromatics • Substi tuti ons — not additions — are typical 20 N a mi ng Benzene D er i va ti ves Cl 1 6 5 4 2 3 Ortho to Cl Meta to Cl P ar a t o C l 1,4-dimethylbenzene Common name: Para-xylene 21 Benzene Derivatives 22 Functional Groups 23 Alcohols • Characterized by –OH group • Name: add –ol to name of hydrocarbon M ethanol Butanol 24 Alcohols C3H5OH: how many structural isomers? H H C H H C H H C H OH H H C H OH H C H C H H 1-propanol 2-propanol Naming: Add -ol to name of 3-C hydrocarbon. Indicate position of OH with number of 25 ...
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