Last Time: Alkanes (C n H 2n+2 ) Last Time: Organic Compounds. Last Time: Intermolecular Forces- BP Increases w/ Increasing Size

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1 Announcements & Agenda (0/02/07) 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.) 1 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) 2 Last Time: Alkanes (C n H 2n+2 ) Last Time: Intermolecular Forces- BP Increases w/ Increasing Size nonpolar. insoluble in water. less dense than water. flammable in air. not a lot of interesting chemistry! but they burn! Melting (blue) and boiling (pink) points of the first 14 n-alkanes in C. 4 1

2 Last Time: 4 Ways to Represent Structures of Organic Compounds (Know These!) 1. Last Time: Naming Alkanes Give the name of CH CH CH CH 2.. STEP 1 Name the longest continuous chain. CH CH CH CH 4. Line Structures - See next slide 5 butane 6 Last Time: Naming Alkanes Give the name of CH CH CH CH STEP 2 Number chain. CH CH CH CH STEP Locate substituents and name (alphabetically). 2,-dimethyl dimethylbutane 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 butane 7 8 2

3 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!!! 9 Alkenes and Alkynes Alkenes contain a double bond between adjacent carbon atoms. Alkynes contain a triple bond. 10 Alcohols and Ethers Aldehydes and Ketones An alcohol contains the hydroxyl (-OH)( functional group. An aldehyde contains a carbonyl group (C=O), which is a carbon atom with a double bond to an oxygen atom. In an ether, an oxygen atom is bonded to two carbon atoms. C O C. 11 In a ketone, the carbon of the carbonyl group is attached to two other carbon atoms. 12

4 Carboxylic Acids and Esters Amines and Amides Carboxylic acids contain 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. 1 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. 14 Summary These are some of the most important 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 biological functional groups!

5 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 Ch. 11 Unsaturated Hydrocarbons Alkenes & Alkynes a ketone Good Practice Problems (Ch 11) 11.05, 11.07, 11.11, 11.1, 11.15, 11.17, 11.19, 11.2, 11.25, 11.27, 11.29, 11.1, 11.5, 11.7, For Ch 10 Do all odd problems! Saturated Hydrocarbons have the maximum # of H atoms attached to each C atom. i.e. alkanes with single C-C C C bonds, C n H 2n+2 Examples: propane: CH 2 CH (C H 8 ) 2-methyl propane: CH CH (C 4 H 10 )

6 Unsaturated Hydrocarbons have fewer H atoms attached to the C chain than alkanes are alkenes with double bonds If one C=C bond, C n H 2n Monounsaturated = 1 D.B. are alkynes with triple bonds If one C CC bond, C n H 2n-2 NOTE: cycloalkanes can also be thought of as unsaturated b/c they have the formula (C n H 2n 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 2n ) Ethene (Ethylene) 1-Methylcyclopropene (1-MCP) Ethene or ethylene is an alkene with the formula C 2 H 4. 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. 2 It inhibits the release of ethylene, thus preventing ripening. 1-MCP 24 6

7 Naming Simple Alkenes use the corresponding alkane name. change the ending to ene Alkene H 2 C=CH 2 H 2 C=CH CH IUPAC ethene ene propene cyclohexene ene Common ethylene ene propylene Naming Simple Alkynes use the corresponding alkane name. change the ending to yne. Alkyne HC CH CH HC C CH IUPAC ethyne propyne Common acetylene Bond Angles in Alkenes & Alkynes According to VSEPR theory: the 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. 27 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. 28 7

8 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 CH = CH cis trans CH = CH Cis-Trans Isomerism Alkenes cannot have cis-trans isomers if a C atom in the double bond is attached to identical groups. Identical H HBr Identical 2-bromopropene 1,1-dibromoethene (not cis or trans) (not cis or trans) H Br C C C C H H Br (similar groups on same side) (similar groups on opp. sides) sides) Unsaturated Fatty Acids Fatty acids in vegetable oils are omega-6 6 acids (the first double bond occurs at carbon 6 counting from the methyl group) A common omega-6 6 acid is linoleic acid CH 2 CH 2 CH 2 CH 2 CH=CHCH 2 CH=CH(CH 2 ) 7 COOH an alkene group 6 a carboxylic acid linoleic acid, a fatty acid group 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