An Introduction to Organic Chemistry

Transcription

1 An Introduction to rganic hemistry

2 rganic hemistry Is Not That Scary

3 rganic hemistry - General Description A. The Study of arbon ompounds B. rganic reminds us of plant or animal origins 1. Natural medicines: morphine, penicillin 2. Natural fibers: cotton, silk, wool 3. Foodstuffs: Fats, carbohydrates, proteins, vitamins 4. Natural rubber. Man-made substances can also be organic 1. Drugs: xylocaine, aspirin, acetaminophen 2. Fibers: nylon, dacron, rayon 3. Polymers: Saran wrap, polyesters, teflon, nylon 4. Synthetic rubber, synfuels

4 Differences Between rganic and Inorganic ompounds Inorganic rganic Elements Present Metals and Nometals Mostly arbon Bonding ovalent and Ionic Mostly ovalent Particles INS & molecules ions & MLEULES Melting Points Relatively igh Relatively Low Boiling Points Relatively igh Relatively Low Electrolytes STRNG to weak weak to NN

5 omparison of Physical Properties of rganic and Inorganic ompounds Name Salt Ethyl alcohol Benzene Formula Nal rganic/inorganic Inorganic rganic rganic Melting Point 804 º -117 º 5 º Boiling Point 1413 º 78 º 80 º Burns in 2? No Yes Yes Water Soluble? Yes Yes No

6 Structural Formulas and ondensed Structures Because organic compounds are molecular in nature, the additional information conveyed in structural formulas is sometimes necessary. Structural formulas show the connections between atoms based on their abilities to form covalent bonds. N N F l N Br

7 Structural Formulas and ondensed Structures Because certain carbon and hydrogen groupings are so common, some abbreviations are used ( 2 ) 2

8 Structural Formulas and ondensed Structures Example of a ondensed Structure: What does the molecular formula 1122 represent? ( 2 ) 4

9 Structural Formulas and ondensed Structures Abbreviations for yclic Structures

10 Families of rganic ompounds Alkanes Aldehydes Alkenes Ketones Alkynes arboxylic Acids Aromatics Esters Alcohols N Amines Ethers N Amides

11 All lasses of rganic ompounds ydrocarbons Functionalized ydrocarbons F,l,Br,S,N Alkanes Alkenes Alkynes Aromatics alides -- -S- -N- Alcohols Phenols Ethers Thiols Dissulfides Amines - -N Aldehydes Ketones Acids Esters Anhydrides Amides

12 Bonding Patterns of arbon Linear hain Branched hain ube Simple Rings Fused Rings

13 Allotropes of arbon

14 ydrocarbons The Simplest lass of rganic ompounds

15 ydrocarbons The Simplest lass of rganic ompounds A. ontain only arbon and ydrogen B. arbon can bond in different ways 4

16 VSEPR Model 180º 120º

17 ydrocarbons The Simplest lass of rganic ompounds A. ontain only arbon and ydrogen B. arbon can bond in different ways 4

18 ydrocarbons The Simplest lass of rganic ompounds B. arbon can bond in different ways (multiple bonds) 120º 120º º 180º 22

19 ydrocarbons The Simplest lass of rganic ompounds. ydrocarbons are further subclassified SATURATED UNSATURATED ALIPATI ARMATI

20 Structural Formulas and Bond Angles Methane (109.5º angles) 120º 180º

21 Structural Representation of Simple Alkanes

22 Alkanes - The Meaning of Line Structure

23 Formulas and Properties of Normal Alkanes omologous Series

24 Formulas and Properties of Normal Alkanes n Molecular ondensed Name Melting Boiling Formula Structural Formula point ( o ) point ( o ) methane ethane propane butane pentane hexane heptane octane nonane decane

25 Uses of ydrocarbons

26 Supplement on ybridization

27 arbon Bonding in Alkanes arbon atoms in alkanes have the following characteristics: arbon is tetravalent: each carbon has four bonds; The four bonds possess tetrahedral geometry; The four bonds are equivalent and have similar properties. The angle between any two bonds of a tetrahedral carbon in any carbon compound is o, the tetrahedral bond angle.

28 The sp 3 ybridization Scheme for arbon Energy 2p 2s 1s excitation 2p 2s 1s } hybridization 2sp 3 1s arbon: ground-state electron configuration arbon: excited-state electron configuration arbon: sp 3 -hybridized electron configuration

29 The sp 3 ybridization Scheme

30 The ybrid rbital Picture of Methane 4 4 hydrogen 1s atomic orbitals Methane 4 carbon sp 3 hybrid orbitals

31 onformations of Alkanes A. Atoms may freely rotate about Single bonds B. Such rotation is not evident in very simple molecules, but can be demonstrated in models of larger molecules 1. Methane - 4 Rotation does not change the spacial relationship between hydrogen atoms. 2. Ethane - 33 Rotation does change the spatial relationship between hydrogen atoms

32 onformations of Alkanes. NFRMATINS - Different arrangements of atoms in a molecule which can be interconverted by rotation about single bonds D. In a given sample of a compound, the molecules usually exist as a mixture of conformations. ne or two conformations are usually the most stable. E. Though they may appear different on paper, different conformers represent the same molecule

33 Isomerism Isomerism, A omplicating Factor in rganic hemistry A. A molecular formula may not convey a unique structure. B. Isomers - ompounds with identical molecular formulas, but different structural formulas.. Example #1: 410 ompound Name Butane Isobutane Melting point -138 o -160 o Boiling point 0 o -12 o Density g/ml g/ml 3

34 Isomerism n-butane butane iso-butane 2-methylpropane

35 Isomerism Isomerism, A omplicating Factor in rganic hemistry A. A molecular formula may not convey a unique structure. B. Isomers - ompounds with identical molecular formulas, but different structural formulas.. Example #1: 410 ompound Name Butane Isobutane Melting point -138 o -160 o Boiling point 0 o -12 o Density g/ml g/ml

36 Isomerism Example #2: 242 ompound 3 3 Name Acetic Acid Methyl formate Melting point 16.6 o -99 o Boiling point 118 o 31 o Density 1.05 g/ml 0.97 g/ml Toxicity

37 ompounds with the Formula

38 ompounds with the Formula

39 Isomerism Two ompounds Are the connectivities of the atoms the same? Yes Are the compounds superimposable? Yes Are the chemical formulas the same? Yes No No No The compounds are not isomers. The compounds are constitutional isomers. The compounds are stereoisomers. The compounds are identical. Are the compounds mirror images? Yes No The compounds are enantiomers. The compounds are diastereomers.

40 Isomer Worksheet

41 Isomerism What is the relationship between these two molecules? 2,3-dimethylpentane 2,3-dimethylhexane

42 Isomerism What is the relationship between these two molecules? and 2,4-dimethylpentane 2,2-dimethylpentane

43 Isomerism What is the relationship between these two molecules? 2,3-dimethylpentane 2,3-dimethylpentane

44 1) ) ) 4)

45 5) l l 3 6) ) )

46 Alkanes Nomenclature Physical and hemical Properties

47 1º, 2º, 3º, and 4º arbons A carbon atom is classified as primary (1º), secondary (2º), tertiary (3º), or quaternary (4º) depending upon whether or not it is directly bonded to a total of one, two, three, or four other carbon atoms, respectively. 1 º 2 º 3 º 4 º

48 1º, 2º, 3º, and 4º arbons - Examples Indicate the number of primary, secondary, tertiary, and quaternary carbons in the following molecules: 1º: 5 2º: 2 3º: 1 4º: 1 1º: 2 2º: 2 3º: 2 4º: 0