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Organic Chemistry The Chemistry of Carbon Compounds Carbon “Organic” Chemistry • Historically, organic compounds are defined as compounds extracted or isolated from plants and animals. – VITALISM: Scientists believed that organic compounds contained a vital force that was only found in living systems • Disproved by Friederich Wohler in 1828 by synthesizing urea using inorganic materials (silver cyanate and ammonium chloride) O AgOCN + NH4Cl C H2N NH2 Friederich Wohler Organic Chemistry • Study of carbon compounds – Composed of carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus, and the halogens • More than 95% of known compounds are organic compounds (Carbon-containing) • Recall – Carbons can have 4 bonds – Nitrogen can have 3 bonds – Oxygen can have 2 bonds – Hydrogen can have 1 bond Common Elements in Organic Compounds C, H, O, (N, S) The Secret to Organic Compounds: the unique carbon atom • CATENATION – Ability of C-atoms to bond to each other so strongly, they can form long chains. Eg. Thousands of C-atoms bonded. – Each carbon can have four bonds, maximum Common organic compound families • HYDROCARBONS: Only C and H – Alkanes, alkenes, alkynes, arenes, aromatic compounds • OXYGEN-CONTAINING – Alcohols, ethers, aldehydes, ketones, carboxylic acids, esters, acid anhydrides • NITROGEN-CONTAINING – Amines, Amides Examples CH HC C HC CH O OH O C C C H CH HC C HC CH O CH3 HO CH2 O H3C acetone C HC OH ascorbic acid F C O HO acetic acid H3C Cl CH2 CH3 propane C O C HO H3C C O CH C CH methyl salicylate benzaldehyde H3C HO Cl F Freon 12 Classification of Hydrocarbons Hydrocarbons Hydrocarbons: Alkanes • • • • Simplest hydrocarbons Contains only C–C and C–H bonds Usually used as fuels Three types – Straight chain alkanes – Branched alkanes – Cyclic alkanes Examples of Alkanes Structures of Alkanes H H C H CH4 = methane H H H H H H H C C C H H H H H H H H C C C C H H H H H CH3 H C C C H H H H CH3CH2CH3 = H = propane CH3CH2CH2CH3 butane CH3 = H3 C CH CH3 isobutane Structural Isomers Structural Isomers Cycloalkanes • Alkanes that form rings are called cycloalkanes CH2 H2C CH2 H2C CH2 H2C CH2 H2C = cyclopropane = cyclobutane = cyclopentane CH2 CH2 CH2 CH 2 CH2 H2C CH2 H2C CH2 CH2 = cyclohexane Haloalkanes • Alkanes with halogens F Cl C F Freon 11 Cl F Cl Cl C C F F Freon 12 Cl F Cl C F Freon 14 Cl Chlorofluorocarbons • Insoluble in water and are unreactive towards substances • Unreactiveness lets them reach the stratosphere and react with the ozone layer Alkenes Alkynes • Contains a C≡C bonds August Kekule and the Dream • C6H6 • • "I fell into a reverie, and lo, the atoms were gamboling before my eyes! Whenever, hitherto, these diminutive beings had appeared to me, they had always been in motion; but up to that time, I had never been able to discern the nature of their motion. Now, however, I saw how, frequently, two smaller atoms united to form a pair; how a larger one embraced the two smaller ones; how still larger ones kept hold of three or even four of the smaller; whilst the whole kept whirling in a giddy dance. I saw how the larger ones formed a chain, dragging the smaller ones after them, but only at the ends of the chain. . . The cry of the conductor: “Clapham Road,” awakened me from my dreaming; but I spent part of the night in putting on paper at least sketches of these dream forms. This was the origin of the Structural Theory." "...I was sitting writing on my textbook, but the work did not progress; my thoughts were elsewhere. I turned my chair to the fire and dozed. Again the atoms were gamboling before my eyes. This time the smaller groups kept modestly in the background. My mental eye, rendered more acute by the repeated visions of the kind, could now distinguish larger structures of manifold conformation; long rows sometimes more closely fitted together all twining and twisting in snake-like motion. But look! What was that? One of the snakes had seized hold of its own tail, and the form whirled mockingly before my eyes. As if by a flash of lightning I awoke; and this time also I spent the rest of the night in working out the consequences of the hypothesis." Aromatic Hydrocarbons H H H H C C C C C C H H H H H C C C C C C H H H 24.3 Aromatic Hydrocarbons • Cyclic structures with alternating C–C and C=C bonds Polycyclic Aromatic Hydrocarbons 24.3 Functional Groups • Determines the properties of the organic compound – Compounds with the same functional group will react similarly • Alkenes: –C=C– bond • Alkynes: –C≡C– bond • Aromatic hydrocarbons: cyclic structure with alternating –C–C– and –C=C– bonds Alcohols • has the general structure R–OH – derived from hydrocarbons and contain OH groups • Polar molecules and are soluble in water (Why?) Some Common Alcohols • CH3OH (methanol) – Used as an industrial solvent – Possible replacement for gasoline in automobiles • CH3CH2OH (ethanol) – Made from fermentation of grain or other sugar materials – Made by reaction of ethylene with water (denatured alcohol) – Used for beverages and fuels Some Common Alcohols • Isopropyl Alcohol – Also known as rubbing alcohol – Used as a disinfectant • Ethylene glycol – Also known as antifreeze – Has multiple –OH groups OH CH H3C H CH3 H H C C OH OH H Alcohols Sterols, ethylene glycol Biological production of ethanol C6H12O6 (aq) enzyme 2CH3CH2OH (aq) + 2CO2 (g) Commercial production of ethanol CH2 CH2 (g) + H2O (g) H2SO4 CH3CH2OH (g) Metabolic oxidation of ethanol CH3CH2OH alcohol dehydrogenase CH3CHO + H2 DRINKABLE vs. DENATURED Alcohol Ethers • Has the R-O-R’ general structure • Compounds in which two hydrocarbons linked by an oxygen are called ethers. • Used as general anesthetic • Used as solvents • Less soluble in water than alcohols Ethers F Cl O H3C CH CH2 CH2 CH3 Cl methyl propyl ether O C O F methoxy flurane CH3 H3C C CH3 CH3 CH3 methyl tert-butyl ether Compounds with a Carbonyl Group • Carbonyl functional group is C=O • Types of different carbonyl compounds – Aldehydes – Ketones – Carboxylic Acids – Esters – Amides Aldehydes and Ketones • Aldehydes must have at least one H atom attached to the carbonyl group: O R C H • Ketones must have two C atoms attached to the carbonyl group: O R C R' Functional Group Chemistry O O O H C H H C CH3 H3C C CH3 formaldehyde acetaldehyde acetone ALMONDS, FORMALIN Carboxylic Acids • Carboxylic acids contain a carbonyl group with an -OH attached. • The carboxyl functional group is -COOH O R C OH • Carboxylic acids are weak acids. VINEGAR, ASPIRIN, FACIAL WASH, ANTS, CITRUS FRUITS, PROTEINS, PRESERVATIVES Common Carboxylic Acids Esters • Esters contain -COOR groups: O R' C OR • Usually have fruity odors and tastes Ester Flavors and Fragrances O O CH2 H3C C CH2 C CH3 H3C O methyl butyrate (apple) benzyl acetate (jasmine) O CH2 H3C C CH2 CH2 O CH3 ethyl butyrate (pineapple) OH O C C HC C HC CH O CH3 CH O C H3C O CH2 O CH2 pentyl acetate (banana) CH2 CH2 CH3 methyl salicylate (wintergreen) Functional Group Chemistry Esters have the general formula R’COOR, where R is a hydrocarbon group. O CH3COOH + HOCH2CH3 CH3 C O CH2CH3 + H2O ethyl acetate Banana: isopentyl acetate Pineapple: ethyl butanoate Apple: methyl butanoate Pear: propyl ethanoate Orange: Octyl ethanoate Raspberry: 2-Methylpropyl ethanoate Oil of Wintergreen: methyl salycilate Esters Galore! allyl caproate amyl acetate amyl butyrate pineapple apple, banana apricot, pear, pineapple amyl caproate apple, pineapple amyl valerate apple benzyl acetate pear, strawberry bornyl acetate pine tree flavor iso-butyl acetate cherry, raspberry, strawberry ethyl acetate peach, pineapple, raspberry ethyl butyrate banana, pineapple, strawberry ethyl caproate strawberry ethyl cinnamate cinnamon ethyl formate lemon, strawberry ethyl heptoate grape, pineapple ethyl isovalerate apple ethyl heptanoate apricot, cherry, grape, raspberry ethyl lactate grape ethyl pelargonate geranyl acetate geranyl butyrate geranyl valerate linalyl acetate linalyl butyrate linalyl formate menthyl acetate methyl benzyl acetate methyl cinnamate methyl phenyl acetate methyl salicylate methyl anthranilate nonyl caprylate octyl butyrate terpenyl butyrate apple grape geranium cherry lavender,sage peach apple, peach peppermint cherry strawberry honey wintergreen grape,jasmine orange parsnip cherry HOW TO MIMIC NATURE: Making synthetic flavoring • • A good cherry is supposed to be tough to formulate. Here is an example of a *minimum* synthetic cherry flavoring: ethyl methyl p-tolyl glycidate 16.0 % iso-amyl acetate 12.0 % iso-butyl acetate 12.0 % p-methyl benzyl acetate 11.0 % benzaldehyde 8.0 % vanillin 7.0 % benzyl alkcohol 5.5 % piperonal 5.0 % ethyl caprate 4.0 % cinnamic aldehyde dimethyl acetal 3.0 % p-tolyl aldehyde 3.0 % cinnamyl anthranilate 3.0 % ethyl caproate 2.0 % geranyl butyrate 2.0 % terpenyl butyrate 0.5 % Amines • Organic bases • Contain carbon, hydrogen, and nitrogen H2N CH2 CH2 CH2 CH2 NH2 CH2 CH2 H2N CH2 cadaverine CH CH2 H2C CH N H CH2 CH2 coniine NH2 CH2 putresine CH2 H2C CH2 CH3 CH2 NH HC C CH HC CH CH3 CH methamphetamine CH3 Amides • composites of carbonyl and amine functionalities • proteins O R C N R' H Name the functional group CH HC C HC CH O OH O C C C H CH HC C HC CH O CH3 HO CH2 O H3C acetone C HC OH ascorbic acid F C O HO acetic acid H3C Cl CH2 CH3 propane C O C HO H3C C O CH C CH methyl salicylate benzaldehyde H3C HO Cl F Freon 12 Compounds with multiple functional groups OH H3C HO CH C CH2 NH C CH2 O CH2 C CH3 O Vitamin B5 Pantothenic acid OH Mango Would you eat this? a-Terpinolene, Ethyl butanoate, 3-Carene, Ethyl acetate, Ethyl 2-butenoate, a-Terpinene, a-Thujene, Dimethyl sulfide, Limonene, b-Phellandrene, Myrcene, pCymen-8-ol, b-Caryophyllene, cis-3-Hexene-1-ol, hexadecyl acetate, 5-Butyldihydro-3H-2-furanone, trans-2-hexenal, Ethyl tetradeconaoate, a-Humulene, sabinene, 2-Carene, Camphene, Ethyl octanoate, 4Isopropenyl-1-methylbenzene 1-Hexanol, a-terpinene, hexanal, Ethyl hexadecanoate, a-Copaene, Hexadecanal, Ethanol, Ethyl propionate, Dihydro-5hexyl-3H-2-furanone, Carveol, Geranial, Ethyl decanoate, Furfural, Butyl acetate, Methyl butanoate, 2,3, Pentanedione, 1,1, diethoxyethane, pentadecanal, Butyl formate, 1-Butanol, 5-Methylfurfural, Ethyl dodecanoate, 2-Acetylfuran, 2 Methyl-1-butanol, 4Methylacetophenoen, Acetaldehyde, Cyclohexane FOSSIL FUELS • Coal, Petroleum, Natural Gas • From decayed organic matter • Makes up 90% of energy used Coal • Main element is carbon, but contains small% of other elements • Complete combustion: – C(s) + O2(g) CO2(g) • Limited supply, strip mining Natural Gas • Principally methane • Formed ages ago probably by heat, pressure, and action of bacteria on organic matter. Chemistry In Action: The Petroleum Industry Crude Oil The Guimaras Oil Spill Gasoline: C5-C12 alkanes • C5-C12 alkanes, some sulfur and nitrogen-containing hydrocarbons • >C15, difficult to combust, causes knock • OCTANE Rating: Isooctane (CH3)3CCH2CH(CH3)2 = 100 Heptane = 0 • Some cpds improving octane rating: tetraethyllead Diesel • Runs on engine designed by Engineer Rudolf Diesel • Petrodiesel: It is a hydrocarbon mixture, (C10-C15) obtained in the fractional distillation of crude oil between 250 °C and 350 °C. • Biodiesel: Methyl esters of fats from natural oils POLYMERS • Poly: Many Meros: Parts • Made up of repeating monomers • Copolymer is a polymer made up of two or more monomers ( CH CH2 CH2 CH CH CH2 )n • Common biopolymers: Proteins, DNA, RNA, starch, cellulose Some commercial polymers • PET: Polyethylene terephthalate – Plastic bottles • Polytetrafluoroethylene – Teflon™ • Polypropylene • Polystyrene • Polyvinyl chloride • Nylon (synthetic polyamide, similar to bonds in proteins) http://www.nationalgeographic.com/education/plastics/index.html References: Hill, JW and Kolb DK. Chemistry for the Changing Times, 7th ed. Prentice Hall International. 1992. Brown, TL. Le May, Jr., HE, and Bursten, BE. Chemistry: The Central Science. 1997. Schmid, G. Organic Chemistry. Mosby-Year Book, Inc. 1996. http://chemed.chem.purdue.edu/genchem/ (accessed on July 28, 2003) Partial list of ingredients for the mango from Snyder, C.H. “The Extraordinary Chemistry of Ordinary Things”, J. Wiley & Sons, 1998. p. 54 Picture of Mango from http://www.globalgourmet.com/ggt/ggt0598/art/mango.jpg (accessed on June 6, 2003)