Atomic Properties of Carbon

Transcription

1 Organic Compounds

2 Atomic Properties of Carbon Organic molecules have structural complexity and chemical diversity. Carbon can lose 4 electrons and have the same electronic configuration as He. OR Carbon can gain 4 electrons and have the same electronic configuration as Ne. Carbon tends to share electrons rather than lose or gain them to obtain a complete octet.

3 More Characteristics of Carbon Carbon has the ability to catenize.

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5 More Characteristics of Carbon Carbon can bond to four, three, or two other atoms. Carbon can bond with single, double, or triple bonds. C-C and C-H bonds are relatively short, strong, and unreactive. Carbon can form a variety of molecules with heteroatoms (O, N, S, halogens)

6 Consider C 4 H 10 O There are 23 different compounds (ethers and alcohols) for this chemical formula. Can you draw Lewis Structures for 2 of these 23 compounds? Note: The oxygen atom can bond to an end carbon or between carbons. Put some structures on the whiteboard.

7 The compound having a structure with a singly bonded OH group on a carbon atom is called an alcohol. The compound having a structure with a singly bonded oxygen atom bonded to two carbon atoms is called an ether. R-OH (alcohol) R-O-R (ether)

8 Other Carbon Compounds Alkyl Halides CH 3 CH 2 I CH 3 CH 2 Br Longer bonds are weaker and more reactive Alkynes and Alkenes CHCH CH 2 CH 2

9 Functional Groups in Organic Chemistry See page 412 of your text. Make flash cards of the various organic compounds and memorize the functional groups. Seriously! Make flash cards.

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12 Hydrocarbons Hydrocarbons contain only C and H. Hydrocarbons can be alkanes, alkenes, alkynes, or aromatic.

13 Alkanes General Formula: C n H 2n+2 The first 10 alkanes Be able to name all of the alkanes having 1 10 C s. Alkanes contain carbon atoms bonded to four other atoms. Thus, only single bonds.

14 Constitutional Isomers Constitutional Isomers have the same chemical formula, but different connectivity of atoms. Carbon compounds can be straight chain, branched chain, or even cyclic. Examples Straight Chain CH 3 CH 2 CH 2 CH 3 Branched Chain CH 3 CH(CH 3 )CH 3 What is/are the molecular formula(s) for the above two compounds?

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16 Line Structures There are three methods of showing organic compound structures: Structural formulas Condensed structural formulas Line structures Draw the three structures for pentane.

17 Careful! There are different ways of drawing the exact same compound. These are NOT constitutional isomers.

18 C 5 H 12 Using condensed structural formulas and line structures, draw all of the constitutional isomers of the above molecular formula. Place your answers on the board.

19 Various Ways of Drawing Organic Molecules

20 IUPAC Nomenclature The International Union of Pure and Applied Chemistry is the organization that has standardized the naming of organic compounds. The following slide indicates the accepted method of naming compounds.

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22 Naming of alkanes: Let s name the various answers you have placed on the board. Name the following alkanes: 1. 2.

23 Alkenes Hydrocarbons with double bonds General Formula: C n H 2n C s with double bonds are sp 2 hybridized These compounds are unsaturated

24 Naming Alkenes Alkenes end with -ene The root chain MUST contain the double bond even if it is not the longest chain. Examples: Cis- 2-pentene Trans-2-pentene

25 Name the following: More Examples

26 Compounds with More than One Double Bond Dienes - Two double bonds Trienes - Three double bonds Etc. Name the following compound:

27 Alkynes General Formula: C n H 2n-2 End with yne C s of triple bond are sp hybridized Name the following compounds:

28 Cyclic Alkanes & Alkenes Naming uses the prefix cyclo- Draw cyclopropane, cyclobutane, and cyclohexane Also, draw 1,2-dimethylcyclopentane and 1-ethyl-3-methylcyclohexane

29 Numbered and Common Positions on Benzene Rings 1,2-dimethylbenzene 1,3-dimethylbenzene 1,4-dimethylbenzene Ortho-dimethylbenzene Meta-dimethylbenzene Para-dimethylbenzene

30 Chiral Molecules Chiral molecules (also known as optical isomers) have the same chemical formula, but they have different three-dimensional molecular structures. Demonstration with models.

31 Chiral Molecules Continued Enantiomers are: molecules with the same connectivity but different orientations in space a.k.a.stereoisomers nonsuperposable optically active have no plane of symmetry

32 Drawing Stereoisomers Cl Cl F C H OH H HO C F Indicates coming toward you In dicates going away f rom you

33 Polarimeter Instrument that measures the degree of rotation of plane polarized light of enantiomers. Dextrorotary (d or +) Rotates light to the right Levorotary (l or -) Rotates light to the left Racemic mixtures contain 50% each of d and l isomers

34 Examples d-glucose l-glucose l-alanine d-alanine d-naproxen l-naproxen d-thalidomide l-thalidomide energy excreted proteins not used pain reliever toxic to the liver morning sickness birth defects (teratogen) Thalidomide is used today for leprosy, cancer, antidepressant, and even aids.

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