Announcements & Agenda (03/02/07)

1. Announcements& Agenda(03/02/07) • Welcome Visitors! Please make yourselves comfortable; we will start with a quiz  • Mid-term grades are only based on lecture • I will give you detailed grade sheets on Monday • Note: most of MT grade was based on Exam 1 • You should read Ch 11/12 this weekend! • Today • Functional groups in organic chemistry (10.5) • Unsaturated compounds (11.1) • Cis-trans isomers (11.2) • Reactivity of unsaturated compounds (11.3)

2. Last Time: Organic Compounds Typical organic compounds • have covalent bonds. • have low melting points. • have low boiling points. • are flammable. • are soluble in nonpolar solvents. • are usually not soluble in water. oil (organic) and water (inorganic)

3. Last Time: Alkanes (CnH2n+2) • nonpolar. • insoluble in water. • less dense than water. • flammable in air. • not a lot of interesting chemistry! • …but they burn!

4. Last Time: Intermolecular Forces- BP Increases w/ Increasing Size  Melting (blue) and boiling (pink) points of the first 14 n-alkanes in °C.

5. Last Time: 4 Ways to Represent Structures of Organic Compounds (Know These!) 1. 2. 3. • Line Structures • - See next slide

6. Last Time: Naming Alkanes Give the name of CH3 CH3   CH3─CH─CH─CH3 STEP 1 Name the longest continuous chain. CH3 CH3   CH3─CH─CH─CH3 butane

7. Last Time: Naming Alkanes Give the name of CH3 CH3   CH3─CH─CH─CH3 STEP 2 Number chain.CH3 CH3   CH3─CH─CH─CH3 1 2 3 4 STEP 3 Locate substituents and name (alphabetically). 2,3-dimethylbutane

8. Functional Groups (Beyond Single Bonds and Only C & H) • a characteristic feature of org. molecules that behave in a predictable way. • composed of an atom or group of atoms. • groups that replace a hydrogen atom in the corresponding alkane. • a way to classify families of organic compounds. Key Point: Functional Groups Give the Molecule their Chemical Personality

9. Functional Groups (Beyond Single Bonds and Only C & H) • a characteristic feature of org. molecules that behave in a predictable way. • composed of an atom or group of atoms. • groups that replace a hydrogen atom in the corresponding alkane. • a way to classify families of organic compounds. Key Point: Differences typically depend on polarity!!!

10. Alkenes and Alkynes Alkenescontain a double bond between adjacent carbon atoms. Alkynescontain a triple bond.

11. Alcohols and Ethers An alcohol contains the hydroxyl (-OH) functional group. In anether, an oxygen atom is bonded to two carbon atoms. –C–O–C– .

12. Aldehydes and Ketones An aldehyde contains a carbonyl group (C=O), which is a carbon atom with a double bond to an oxygen atom. In a ketone, the carbon of the carbonyl group is attached to two other carbon atoms.

13. Carboxylic Acids and Esters Carboxylic acidscontain the carboxyl group, which is a carbonyl group attached to a hydroxyl group. O ║ — C—OH An ester contains the carboxyl group between carbon atoms.

14. Amines and Amides In amines, the functional group is a nitrogen atom. | —N — In amides, the hydroxyl group of a carboxylic acid is replaced by a nitrogen group.

15. Summary  These are some of the most important biological functional groups!

16. Some functional groups in consumer products • BENGAY • Camphor – a ketone • Menthol – an alcohol • Methyl salicylate – an ester and a phenol • Neopsporin • Miconazole – many functional groups (ether, chloro) • Dimethyl ether propellant • Halls cough • Menthol- an alcohol

17. Some functional groups in spices • Nutmeg • Myristicin – a polyether, an alkene, benzene ring • Elemicin • Safrole • Anise • Anethole – an ether, an alkene, benzene ring • Caraway seeds • d-Carvone – a ketone • Spearmint • l-Carvone – a ketone

18. Ch. 11 Unsaturated Hydrocarbons Alkenes & Alkynes

19. 15 Good Practice Problems (Ch 11) 11.05, 11.07, 11.11, 11.13, 11.15, 11.17, 11.19, 11.23, 11.25, 11.27, 11.29, 11.31, 11.35, 11.37, 11.40 For Ch 10 – Do all odd problems!

20. Saturated Hydrocarbons • have the maximum # of H atoms attached to each C atom. • i.e. alkanes with single C-C bonds, CnH2n+2 • Examples: propane: CH3—CH2—CH3 (C3H8) 2-methyl propane: CH3—CH—CH3 (C4H10) │ CH3

21. Unsaturated Hydrocarbons • have fewer H atoms attached to the C chain than alkanes • are alkenes with double bonds • If one C=C bond, CnH2n • Monounsaturated = 1 D.B. • are alkynes with triple bonds • If one C≡C bond, CnH2n-2 NOTE: cycloalkanes can also be thought of as unsaturated b/c they have the formula (CnH2n)

22. FUN WITH KETCHUP

23. Unsaturated compounds are oxidized relative to saturated compounds • Oxidation of organic compounds means: • Replacement of hydrogen atom with a more electronegative atom (oxygen or nitrogen) OR • Loss of H atoms & replacement with a double bond

24. Ethene (Ethylene) Ethene or ethylene • is an alkene with the formula C2H4. • has two carbon atoms connected by a double bond. • has two H atoms bonded to each C atom. • is flat with all the C and H atoms in the same plane. • is used to accelerate the ripening of fruits.

25. 1-Methylcyclopropene (1-MCP) • http://www.smartfresh.com/ • It inhibits the release of ethylene, thus preventing ripening.

26. Naming Simple Alkenes • use the corresponding alkane name. • change the ending to –ene Alkene IUPAC Common H2C=CH2 ethene ethylene H2C=CH─CH3 propenepropylene cyclohexene

27. Naming Simple Alkynes • use the corresponding alkane name. • change the ending to –yne. Alkyne IUPAC Common HC≡CH ethyne acetylene HC≡C─CH3 propyne

28. Bond Angles in Alkenes & Alkynes According to VSEPR theory: • the 3 groups bonded to C atoms in a double bond are at 120° angles. • alkenes are flat because the atoms in a double bond all lie in the same plane. • the 2 groups bonded to each carbon in a triple bond are at 180° angles.

29. How do you make a double bond? • The 1st bond is made by “orbitals” overlapping between atoms, and is called a “sigma” (σ) bond. • The 2nd bond is made by sideways p orbitals (not directly between the atoms) and is called a “pi” (π) bond. • This is why a single bond can rotate. But the π bond part of a double bond can’t rotate – you’d have to break it.

30. More Steroisomers: Cis-Trans Isomers In an alkene, the double bond • is rigid, i.e. NO ROTATION around the double bond! • holds attached groups in fixed positions. • makes cis/trans isomers possible. • Important in nature – such as in pheromones CH3 CH3 CH3 CH = CH CH = CH cistransCH3 (similar groups on same side) (similar groups on opp. sides)

31. Cis-Trans Isomerism • Alkenes cannot have cis-trans isomers if a C atom in the double bond is attached to identical groups. Identical Identical 2-bromopropene1,1-dibromoethene (not cis or trans) (not cis or trans) H H Br H

32. Unsaturated Fatty Acids • Fatty acids in vegetable oils are omega-6 acids (the first double bond occurs at carbon 6 counting from the methyl group) • A common omega-6 acid is linoleic acid CH3CH2CH2CH2CH2CH=CHCH2CH=CH(CH2)7COOH 6 linoleic acid, a fatty acid an alkene group a carboxylic acid group

33. Trans Fats In vegetable oils, the unsaturated fats usually contain cis double bonds. • During hydrogenation, some cis double bonds are converted to trans double bonds (more stable) causing a change in the fatty acid structure. • If a label states “partially” or “fully hydrogenated”, the fats contain trans fatty acids.