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ORGANIC CHEMISTRY

ORGANIC CHEMISTRY. Organic chemistry is the study of carbon chemistry and the compounds of carbon. Majority of chemical compounds on earth are organic. The main elements involved in organic chemistry are C, H, O, N, HC = hydrocarbon

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ORGANIC CHEMISTRY

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  1. ORGANIC CHEMISTRY Organic chemistry is the study of carbon chemistry and the compounds of carbon. Majority of chemical compounds on earth are organic. The main elements involved in organic chemistry are C, H, O, N, HC = hydrocarbon Organic chemistry reminds us of plants and animals but is not limited to such. Natural medicines: penicillian, cortisone, streptomycin Manmade medicines: novocaine, sulfa drugs, aspirin. Natural textile fibers: nylon, dacron, lytex, rayon Polymers: saran, teflon, styrofoam, plastics, polyethylene, PBC’s

  2. FUNDAMENTAL ASPECTS OF CARBON CARBON WILL HAVE 4 COVALENT BONDS NITROGEN WILL HAVE 3 COVALENT BONDS OXYGEN WILL HAVE 2 COVALENT BONDS HYDROGEN WILL HAVE 1 COVALENT BOND REMEMBER TO MAKE SURE THESE ATOMS ALWAYS HAVE THE ABOVE # OF BONDS

  3. CLASSIFICATION OF HYDROCARBONS HYDROCARBONS ALIPHATIC HYDROCARBONS AROMATIC HYDROCARBONS (unsaturated hydrocarbons) SATURATED UNSATURATED HYDROCARBONS HYDROCARBONS BENZENE AND FUSED-RING DERIVATIVES AROMATIC alkenes alkynes HYDROCARBONS (CnH2n) (CnH2n- 2) Alkanes Cycloalkanes (CnH2n+ 2) (CnH2n)

  4. BONDING IN ORGANIC CHEMISTRY 1. Carbon forms four covalent bonds. Carbon has either 4 attached groups (single bonds), or three attached groups (two single bonds and a double), or two attached groups (both double bonded or one single plus one triple). H H H    H H H - C - H H - C - C - H C = C H - CC - H    H H H H H methane ethane ethene ethyne 2. Nitrogen forms three covalent bonds and has one unshared pair of electrons. The bonds may either be three singles, or one single plus a double, or a triple bond. .. .. H - N - H H - O - N = O H - C  N  N  N:  H ammonia nitrous acid hydrogen cyanide nitrogen molecule

  5. BONDING IN ORGANIC CHEMISTRY • 3. Oxygen forms two covalent bonds and has two unshared pairs of electrons. The bonds may either be two singles or one double. • H :O: H :O: •  . .    . . • H - O - H H - C - .O. - H H - C - H H - C - C - .O. - H •   • H H • water methanol methanal acetic acid • (methyl alcohol) (formaldehyde) • Hydrogen forms one covalent bond and it is always single bonded. • SATURATED: a hydrocarbon in which all carbon atoms are bonded to the maximum number of hydrogen atoms. There are no carbon-carbon double or triple bonds. • UNSATURATED: a hydrocarbon which contains double or triple carbon-carbon bonds, the compound does not have the maximum number of hydrogen atoms.

  6. ISOMERS STRUCTURAL - compounds with the same molecular formula but different structures. C5H12 - Structural H  H - C - H  H H  H     H - C - HH - C - C - C - H    H H H H HH  H HH  H         H - C - C - C - C - C - HH - C - C - C - C - HH - C - H         H H H H HH H H HH Pentane, b.p. 36° C2 - Methylbutane, b.p. 28° C2,2-Dimethylpropane, b.p. 9.5°C Fractional Distillation N - butane MP = -138ºC BP = -.5ºC isobutane MP = -160ºC BP = -11.7ºC branched boils at higher BP, requires more energy to boil.

  7. ISOMERS GEOMETRIC- different orientation of ligands in space C2H2Br2 Br Br H Br C = C C = C H H Br H cis trans

  8. SHAPE, GEOMETRY, STRUCTURE Since Organic chemistry is limited to a small number of elements, why are there so many molecules and compounds possible? Structure & geometry are very important. Remember molecules exist in 3-D and Chem Rx occur because the approach is easiest (requires less energy) - use molecules to show difficulty of approach (steric hindrance) Different geometry, shape or structure will give molecules different physical or chemical properties. Most common geometry for carbon compounds: Linear, trigonal planar, tetrahedral, cyclo Stability can be demonstrated by using models and feeling the amount of stress needed to make the model.

  9. ORGANIC CHEMISTRY - THE CHEMISTRY OF CARBON # of carbonname example atoms 1Meth Methane CH4 2EthEthane C2H6 3PropPropaneC3H8 4butButaneC4H10 5 pent pentane C5H12 6hexhexane C6H14 7heptheptane C7H16 8octoctane C8H18 9nonnonane C9H20 10decdecane C10H22

  10. THE FIRST TEN CONTINUOUS-CHAIN ALKANES Name Molecular formula Number of possible isomers Methane CH4 1 Ethane C2H6 1 Propane C3H8 1 Butane C4H10 2 Pentane C5H12 3 Hexane C6H14 5 Heptane C7H16 9 Octane C8H18 18 Nonane C9H20 35 Decane C10H22 75

  11. Physical Properties of Selected Alkanes MOLECULAR MELTING BOILING DENSITY AT NAME FORMULAPOINT (°c) POINT (°C) 20°C (g/mL) Methane CH4 -183 -162 (Gas) Ethane C2H6 -172 -89 (Gas) Propane C3H8 -188 -42 (Gas) Butane C4H10 -138 0 (Gas) Pentane C5H12 -130 36 0.626 Hexane C6H14 -95 69 0.659 Heptane C7H16 -91 98 0.684 Octane C8H18 -57 126 0.703 Decane C10H22 -30 174 0.730 Dodecane C12H26 -10 216 0.749 Tetradecane C14H30 6 254 0.763 Hexadecane C16H34 18 280 0.775 Octadecane C18H38 28 316 (Solid) Eicosane C20H42 37 343 (Solid)

  12. ALKANES Saturated hydrocarbons “single bonds” (CnH2n+ 2) Butane Octane Hexane Properties - non polar molecules - insoluble in water - less dense than H2O - dissolves fats, oils and waxes - fuel

  13. Cyclic Hydrocarbons The names of cyclic hydrocarbons begin with the prefix cyclo- followed by the name of the alkane with the same number of carbon atoms.

  14. ALKENES & ALKYNES Unsaturated Hydrocarbons “Double & Triple” Bonds butene octene hexene butyne octyne hexyne Properties - Insoluble in water - Nonpolar molecules - Undergo many chemical Rx Addition Rx: C2H2 + 2H2  C2H6 - Add to form polymers

  15. NOMENCLATURE 1. Find longest chain - separate body from branches 2. Name body based on #1 chain - use prefixes 3. Determine type of bonds between carbon atoms 4. If functional group present - number carbons 5. Name compound using lowest numbering - body contains functional groups - branches are represented by prefix & - yl

  16. AROMATIC HYDROCARBONS Benzene Properties - Insoluble in water - used as solvents or fuels - narcotic vapors (cancerous)

  17. Chlorinated Hydrocarbons When hydrogen atom or atoms of a hydrocarbon are substituted by chlorine, a chlorinated hydrocarbon is formed. Chlorinated hydrocarbons have many useful properties. Dichloromethane is used as a solvent and paint remover. Trichloromethane (chloroform) is also a solvent and at one time was used as an anesthetic. It is now considered hazardous.

  18. CHLORINATED HYDROCARBONS CH3Cl - methyl chloride - make silicones CH2Cl2 - methylene chloride - solvent for paint remover CHCl3 - chloroform - anesthetic CCl4 - carbon tetrachloride - dry cleaning solvent CCl4 + H2O  COCl2 + HCl phosgene, poison gas WWI CFC’s DDT (dichloro diphenyl tri chloro ethane) PCB (polychlorinated biphenyls) Properties - slightly polar - does not dissolve in H2O, dissolves in fats and oils

  19. TYPES OF ORGANIC REACTIONS 1. Addition Rx an unsaturated reactant becomes a saturated product R-CH=CH-R + -y  R-CH-CH-R 2. Elimination Rx a saturated reactant becomes an unsaturated product R-CH-CH2  R-CH=CH2 +  - y 3. Substitution Rx an atom (or group) from an added reactant substitutes for one in the organic reactant

  20. Functional Groups Atoms or groups of atoms attached to hydrocarbon skeletons give the compounds characteristic chemical and physical properties and are known as functional groups. Double and triple bonds as well as halogen substituents are examples of functional groups.

  21. ORGANIC NOMENCLATURE FUNCTIONAL GROUPS containing oxygen R - OH -ol alcohol R - O - R ether ether carbonyl C=O R- HC = O -al aldehyde R - C = O -one ketone l R R - C - O-H -oic acid carboxylic acid ll O R - C - O - R -oate ester ll O

  22. ORGANIC NOMENCLATURE FUNCTIONAL GROUPS containing nitrogen R – NH2 -amine amine R – C=O -amide amide l NH2

  23. Functional Groups in detail

  24. ALCOHOL MeOH – wood alcohol – methanol CH3OH - oxidized in body to formaldehyde - 1oz MeOH causes blindness EtOH – grain alcohol – ethanol C2H5OH - not poisonous in low concentrations - 500 mL 200 proof rapidly ingested will kill IPA – Isopropyl alcohol (rubbing alcohol) - C3H7OH 2-propanol -toxic (dosage) causes nerve damage, blindness and/or death, it’s a poison. - FAS - depressant - heavy drinking alter brain cell functions, causes nerve damage, shortens life span

  25. ALDEHYDES/KETONES - formaldehyde - makes plastic - embalming - disinfectant - benzaldehyde (oil of almond) - maraschino cherry flavor - perfume, flavoring - acetone C3H6O - nail polish remover; common solvent for fats, rubber, plastics, & varnishes. Used in paint and varnish removers. - MEK – methyl ethyl ketone – solvent in oil paints and glues. Also formed in the blood stream in ketosis (a problem in diabetes).

  26. Ketone functional group • Ketone functional group is basis for soft contact polymer • Carbonyl group is C=O • Ketone contains two hydrocarbon chains attached to carbonyl group

  27. Naming ketones • Obtain root name • Count total number of C atoms • Remove –e and replace with –one • Location of carbonyl group • Count carbon atoms from shortest end

  28. ETHERS - solvent - flammable - react w/O2 to form unstable peroxides - Diethyl ether  anesthetic 1842; side effects include nausea & vomiting. - MODERN ANESTHETICS include methy propyl ether (Neothyl) and methoxyflurane (penthrane; CHCl2CF2OCH3) - MTBE (methyl tert-butyl ether) – reduce CO emissions in automobiles but is a suspected carcinogen. - ethylene oxide (C2H4O; cyclic) is used to make ethylene glycol which in turn is used to make polyester fibers and antifreeze.

  29. Naming Ethers • When the hydrocarbon groups are different, the name orders the two group alphabetically and ends in ether. • Butyl methyl ether: H3CCH2CH2CH2-O-CH3 • When the groups are the same the prefix di- is used. • Dimethyl ether: H3C-O-CH3

  30. CABOXYLIC ACIDS - carboxylic acids are polar and form hydrogen bonds thus leading to higher boiling points. (formic acid; 46 g/mol has bp of 101oC whereas ethanol; 46 g/mol has bp of 78oC). They are weak acids and react with bases to form salts. -formic acid – methanoic acid - ant sting - CH2O2 -acetic acid – ethanoic acid - vinegar - CH3COOH -butyric acid – butanoic acid – rancid butter -benzoic acid – Listerine -citric acid – sour flavor in oranges, lemons, & limes -lactic acid – imparts tartness to pickles, sauerkraut, & sweat. -cause of muscle pain & soreness after exercise.

  31. ESTERS carboxylic acid + alcohol  ester + H2O - sodium benzoate - preservative - fragrances - pineapple = ethyl butyrate - rum = ethyl formate - wintergreen = methyl salicylate - oil of jasmine has benzyl acetate (C6H6)-CH2-O-CO-CH3 -rose = benzyl butanoate

  32. The name game • Ester contains two name parts • First: attached to O atom in main chain • Second: all C atoms in main chain, subtract -e and add -oate

  33. AMINES/AMIDES Organic bases – similar to ammonia NH3 in odor and basicity. Many amines have unpleasant odors like trimethylamine (smell of rotting fish) & putrescine (component of decaying animal flesh) H2N-(CH2)4-NH2 Amines are biologically important for example some illicit drugs like amphetamine & methamphetamine are amines and amino acids & proteins contain amines/amides. Nylon is a polyamide. Carboxylic acid + amine = amide + H2O

  34. Functional group review

  35. Functional group review Penicillin G shown below, a drug that inhibits the production of bacterial cell walls:

  36. Functional group review synthetic analog of bryostatin, a natural anticancer agent: derivative of Neomethymycin, an antibiotic

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