12.01 Organic Chemistry

Transcription

1 12.01 rganic hemistry hemistry of arbon An Introduction to nomenclatures, structures and reactions Dr. Fred mega Garces hemistry 100 Miramar ollege 1 rganic hemistry

2 What is rganic hemistry? rganic hemistry: Study of carbon containing compounds. Everything else is considered inorganic. ver 5 million chemicals known of these thousands are inorganic. Why are there so many organic compounds? l Br N l N Br F F F F ( )n F F F F Br Br N Br 2 2 F l 3 Br 3 3 Br Br 3 2 R ( 2 ) N rganic hemistry

3 The magic arbon atom Difference between organic and inorganic is -atom ability to form very long chain Inorganic compound will become unstable after with 12 or more atoms. -atoms ability to form very strong covalent bond means molecules can possess 100 or more atoms 3 rganic hemistry

4 Evolution of rganic hemistry an man artificially create a living animal from chemicals? - magnitude of question concerning organic compound Prior to 1828, organic compounds can only be obtained from living organism Fredrick Wohler prepared urea - chemical in urine (an organic compound) N 4 l + AgN g N 2 --N 2 + Ag Now a days the bulk of organic compounds is manufactured in the lab. 4 rganic hemistry

5 Source of rganic ompound rganic chemicals isolate from nature. Nature has her huge laboratory and is constantly synthesizing chemicals through biosynthesis. Today we can manufacture these same chemicals in the lab Ethanol Mescaline affeine Tetrahydrocannabinol T 5 rganic hemistry

6 Lewis Dot Structure : Number of bonds for nonmetal atom Lewis Dot Structure and VSEPR: revisited N X Val. e # Bonds N 3 2 -l 6 rganic hemistry

7 arbons with single bond : Forms of arbons Methane, 4 Tetrahedral sp 3 arbons with double bonds ethene, 2 6 Trig. planar 120 sp 2 arbons with triple bonds ethyne 2 2 Linear 180 sp 7 rganic hemistry

8 Structure - Ways of presenting organic ompounds onsider: Ethanol and dimethylether 2 6 Molecular formula - indicate type and number of atoms Structure formula - shows connectivity of atoms in a compound Ethanol Dimethylether ondense formula - shows connecting group of atoms in a compound Ethanol, 3 2 Dimethylether, 3 3 Shorthand notation - shows hydrocarbon as "R" and functional group as is. Ethanol R- Dimethylether R--R Stick form - shows hydrocarbons as lines with functional group Ethanol Dimethylether Isomers - ompounds that have the same formula but different structures Ethanol and dimethylether have the same formula but are different compounds and therefore possesses different properties Ethanol is the drinkable alcohol, while dimethyl ether was used as an anesthetic. 8 rganic hemistry

9 rganic ompounds; the Family Tree. rganic ompounds ydrocarbons eteroatoms Aliphatics Alkane Alkene Alkyne cyclo Aliphatics Aromatic 3 3 N 9 rganic hemistry

10 The Alkanes Alkanes n 2n+2 ydrocarbons with only single bonds Methane 4 Ethane 2 6 Propane 3 8 Butane 4 10 Pentane rganic hemistry

11 Degree of arbon a) primary carbons, 1 - a) carbons bonded to only one other carbon b) secondary carbons, 2 - carbons bonded to two other carbons c) tertiary carbons, 3 - carbons bonded to three other carbons d) quaternary carbons, 4 - carbons bonded to four other carbons rganic hemistry

12 Prefix and the Number of arbons # of Molecular Formula Prefix Alkane name Structure and isomers group name 1 4 meth- methane 4 methyl eth- ethane ethyl prop- propane propyl, i-propyl but- butane butyl, iso-butyl, sec-butyl, tert-butyl pent- pentane pentyl,, hex- hexane etc hept- heptane oct- octane non- nonane dec- decane - 12 rganic hemistry

13 Isomers are molecules with the same chemical formula but different structural formula. Pentane Isomers n-pentane, iso-pentane, neo-pentane exane n-hexane 2-methylpentane 3-methylpentane 2,4-dimethylbutane 2,2-dimethylbutane 13 rganic hemistry

14 Alkyl group (in naming scheme) Alkyl group - An important idea in the naming scheme is the group of atoms attached to a carbon chain. yl - suffix indicating group methane g methyl First 5 alkyl groups and their isomers: 1. Methyl 2. Ethyl 3.Propyl: n-propyl, isopropyl. 4.Butyl: n-butyl, sec-butyl, iso-butyl, tert-butyl. ethane g ethyl Pentyl: n-pentyl, sec-pentyl, iso-pentyl, neo-butyl 14 rganic hemistry

15 Rules of the game: Alkane ( n 2n+2 ) IUPA Nomenclature 1. Find the longest continuous chain of carbon atoms. Assign this chain as the parent name. 2. Determine the substituents (groups) attached to the parent chain 3. Assign attachment position of group to main chain by starting at end which gives lowest position number.* 4. Identical groups attached to the main chain are designated with prefixes. 2-di, 3-tri, 4-tetra, 5-penta 5. Different groups attached to main chain are written in alphabetical order. 6. Alkyl halides: alogen atoms (group) are designated as halogen prefix. F - Fluoro, l-hloro, Br- Bromo, I- Iodo 7. Alkyl groups (see previous page) * The numbering scheme should be chosen such that the sum of the position in which group are attached add up to the lowest sum. 15 rganic hemistry

16 IUPA nomenclature, an example onsider the following hexane compound: eptane ( 7 16 ) 1. Pentane 2. Methyl 3. arbon # 2 & # ,3 = position methyl = group pentane = parent name 5. Two methyl g dimethyl 6. Name: 2,3-dimethylpentane 16 rganic hemistry

17 Functional Group Name -Suffix group Example 1 Aliphatics -ane, -ene, 2 Alcohol -ol -yen 3 Ether - ether 4 Aldehydes -al 5 Ketones -one 6 arboxylic acid -oic acid 7 Ester -ate 8 amine -amine 9 amide -amide,,,, propane, propene, proyne = propanol R R', ethylpropylether R R R R R R N R' R' R' N R' R' R', propanal, propanone, propanoic acid, methyl propanoate N, triethyl amine N, N-methylpropamide 17 rganic hemistry

18 Alkenes and Alkynes Alkenes n 2n Alkynes n 2n-2 ydrocarbons with multiple bonds - Ethene, Ethyne, Propene, Propyne, 3 4 Note: If there is more than one multiple bond _ poly unsaturated i.e., 18 rganic hemistry

19 Geometric Isomers More on Alkenes is 2-butene Trans 2-butene an t rotate the double bond which makes these molecules unique compounds or Geometric isomers. Life example: 11-cis-retinal g all trans retinal R Visual pigment (rhodopsin) hn dark with enzyme R Signals optic nerve cell 19 rganic hemistry

20 Nomenclature: Alkenes and Alkyne more rules of the game: Alkene ( n 2n ) -ene (suffix) 1. - ene suffix for alkenes 2. Main chain must include the double bond. 3. position of double bond indicated by prefix numbering location. 4. For multiple double bonds : di = 2 double bonds tri = 3 double bonds 2-propyl-1-pentene 2-methyl-1,3,5-heptatriene Alkyne ( n 2n-2 ) -yne (suffix) 1. - yne suffix for alkynes 2. Nomenclature rules are similar to that of alkenes 3-ethyl-4-methyl-1-hexyne 20 rganic hemistry

21 Aromatics: nomenclature 1. Monosubstituted a. group benzene N 2 l Br 2 3 b. special name 2. Two substituted groups - use prefix for position 3 N 2 X o (ortho) 3. Three substituted groups m(meta) p(para) - requires # scheme (lowest position scheme) 5 X 1 4. Benzene as a group - phenyl rganic hemistry

22 Summary 22 rganic hemistry