1. Chem. 1B – 12/8 Lecture

2. Announcements I Lab Final –On Wed./Thurs. this week –Will be 25 questions, multiple choice –Bring green type Scantron 882E –Questions will be similar to quiz questions, pre-lab questions, and post-lab questions Make Up Quiz – –Today – A and B versions –(periodic table on back – in case you can’t see it) –following announcements

3. Announcements II Mastering Chemistry –Chapter 20 questions – due 12/15 –Introduction (“due” 12/16) WORTH 0 Points Thursday –Last Day of Class –Finish Organic Chemistry (Functional Groups) –Teaching Evaluations –Review of Material Since Exam 3 Final Exam –Thursday, Dec. 17, 12:45-2:45 (sect. 2 to 6 here)

4. Announcements III Final Exam – cont. –Help Session (Tues. 12/15, available before 12 or after 3:30) –Format(52 multiple choice questions – including two bonus questions – Bring Scantron SC982-E) –All material covered is possible for questions –Less emphasis on calculations –Some questions combining sections (example combustion of hydrocarbons combining thermodynamics and organic chemistry) –Some questions will come from: exams, quizzes, in-class questions, or homework questions

5. Announcements IV Final Exam – cont. –I will post some example organic chemistry questions and solutions to make up quiz Today’s Lecture – Organic Chemistry –Alkynes –Reactions –Aromatic Compounds

6. Announcements V Taking Other Chemistry Classes at CSUS? –If your program requires you to take Chem 20, 24 or Chem 31, I recommend taking them sooner (rather than later when you have forgotten concepts learned here) –Getting into labs (Chem 31 and Chem 25/20L) can be hard due to impaction, but can “crash” labs (a few seats are reserved for adding at beginning of semester)

7. Chapter 20 Organic Chemistry Alkynes –Contain at least 1 carbon-carbon triple bond –Naming (replace –ane ending with –yne with number referring to end of triple bond closest to the #1 carbon) –Triple bond uses sp hybridization and leads to a linear structure –Example: CH 3 CH=CHCH 3 is 2-butyne (linear) Carbon skeleton structure

8. Chapter 20 Organic Chemistry Alkynes – cont. –Alkynes are considerably more energetic than alkenes –Used less by organic chemists (harder to synthesize, fewer uses) –Used by Dr. Spence in ene-diyne compounds (generates cyclic radical)

9. Chapter 20 Organic Chemistry Some Basic Hydrocarbon Reactions –Combustion (all types, but alkynes generate more energy than alkenes and alkanes generate the least energy) H x C y + O 2 (g) → CO 2 (g) + H 2 O(g) (unbalanced, but be able to balance) –Halogenation of Alkanes Example CH 3 CH 3 (g) + Cl 2 (g) → CH 3 CH 2 Cl(g) + HCl(g) Products are typically more stable than reactants (C-X bonds are pretty stable)

10. Chapter 20 Organic Chemistry Some Basic Hydrocarbon Reactions –Halogenation of Alkanes – cont. Occurs by “free radical” mechanism: Cl 2 (g) + heat or light → 2Cl(g) (where “” shows free radical) Cl(g) + CH 3 CH 3 (g) → HCl(g) + CH 3 CH 2 (g) CH 3 CH 2 (g) + Cl 2 (g) → CH 3 CH 2 Cl(g) + Cl(g) Free radical reactions are hard to control, so will also produce related compounds (e.g. CH 2 ClCH 2 Cl(g)) Syngas reactions also are free radical reactions

11. Chapter 20 Organic Chemistry Some Basic Hydrocarbon Reactions –Alkene Reactions (addition to double bond) Hydrogenation (also works with alkynes) –Example: CH 2 =CH 2 (g) + H 2 (g) → CH 3 CH 3 (g) –Requires H 2 at high pressure and catalyst Halogenation –Example: CH 3 CH=CH 2 (g) + Cl 2 (g) → CH 3 CHClCH 2 Cl(g) –Can also use HX (hydrohalide gas) as reactant –In this case both H and X are added to alkene carbons –CH 3 CH=CH 2 (g) + HCl(g) → CH 3 CHClCH 3 (g) + CH 3 CH 2 CH 2 Cl (g) both products possible, but only one observed

12. Chapter 20 Organic Chemistry Some Basic Hydrocarbon Reactions –Alkene Reactions – Halogenation – cont. Why is only CH 3 CHClCH 3 (g) observed? Markovnikov’s Rule (H added to side with most Hs) What is expected product of HCl(g) + ?

13. Chapter 20 Organic Chemistry Questions 1.Give the name for the following compounds: a)CH 3 CH=C(CH 3 ) 2 b) CH 2 =CH(CH 3 )CH=CH 2 c) (CH 3 ) 2 CHC=CH 2. Predict the product of HBr(g) + 3.What type of product is produced by hydrogenation of alkenes? a) alkanesb) alkynesc) dienesd) halocarbons

14. Chapter 20 Organic Chemistry Aromatic compounds –Benzene, the simplest aromatic compound –Formula = C 6 H 6 –Structure (see below) = However, all C – C bonds are the same length (due to all sp 2 hybridization which perfectly matches 120° bond angle for hexagon) H H HH H H

15. Chapter 20 Organic Chemistry Aromatic compounds – cont. –While adding double bonds makes compounds less thermodynamically stable, benzene and other aromatic compounds (compounds containing benzene ring) are relatively stable both thermodynamically and kinetically –Some due to “resonance stabilization” –Due to stability, reactions are different than alkene reactions

16. Chapter 20 Organic Chemistry Aromatic compounds – cont. –Substituted aromatics (benzene ring plus substituent) –Examples of monosubstituted aromatics methylbenzene = toluene chlorobenzene Cl OH hydroxybenzene = phenol isobutylbenzene or 2-phenylbutane

17. Chapter 20 Organic Chemistry Aromatic compounds – cont. –Disubstituted aromatics –Number around ring starting with earlier (alphabetical) constituent hydroxy before methyl so right C = #1 OH 1 23 4 5 6 name = 1-hydroxy-2- methylbenzene 1, 2 disubstitution is also known as “ortho” Cl name = ? 1,3-disubstitution = “meta” and 1-4-disubstitution = “para”

18. Chapter 20 Organic Chemistry Aromatic compounds – cont. –Substituent Naming (other than alkyl) SubstituentName -BrBromo- -ClChloro- -OHHydroxy- -NH 2 Amino-

19. Chapter 20 Organic Chemistry Aromatic compounds – cont. –Reactions: substitution reactions –Examples: + Cl 2 FeCl 3 (catalyst) Cl + HCl Cl replaces H + CH 3 Cl AlCl 3 (catalyst) + HCl CH 3 replaces H

20. Chapter 20 Organic Chemistry More Questions 1.Predict the product of the following reactions: a)(CH 3 )CH=CH 2 + Br 2 → b)trans (CH 3 )CH=CH(CH 3 ) + H 2 (g) → c)(CH 3 ) 2 C=CH(CH 3 ) + HBr → 2.Give the names of the following compounds: NH 2 Br