Chapter 12 Organic Chemistry: The Infinite Variety of Carbon Compounds

Organic Chemistry Chemistry of carbon-containing compounds Most of these come from living things Not necessarily the case ~30 million chemical compounds known 95% are compounds made of carbon Chapter 9

Carbon Able to bond strongly to other carbon atoms Forms long chains Very few other atoms can form short chains, let alone long chains Capable of forming ring structures Bonds strongly to other elements In particular, H, O, and N Chapter 9

Hydrocarbons Made of carbon and hydrogen Several classes Alkanes Contain only single bonds Saturated hydrocarbons Each C atom bonded to maximum number of H atoms Chapter 9

Alkanes Chemical formula CnH2n+2 n = 1, 2, 3, … CH4, methane, simplest one C2H6, ethane All have –ane ending Follow a pattern Chapter 9

Condensed structural formulas Show how many hydrogens are attached to each carbon CH3-CH3 for ethane Structural formulas show how atoms are bonded together Chapter 9

Isomerism Isomers: compounds with same molecular formula but different structural formulas Differences in structure may give rise to differences in chemical and physical properties Chapter 9

Number of possible isomers increases rapidly with the number of carbons C30H62 – >4 billion possible isomers Chapter 9

Chapter 9

Properties of Alkanes Main property: will burn Chapter 9

Cyclic Hydrocarbons Carbon atom chains in form of rings Can be represented by structural formulas or symbolic representations Chapter 9

Unsaturated Hydrocarbons Can have more hydrogen atoms added Very important in biological systems Alkene: hydrocarbon that contains one or more carbon-to-carbon double bonds General formula of CnHn Simplest: ethylene, C2H4 Chapter 9

General formula of CnH2n–2 Simplest: acetylene, C2H2 Alkyne: hydrocarbon that contains one or more carbon-to-carbon triple bonds General formula of CnH2n–2 Simplest: acetylene, C2H2 Chapter 9

Properties of Alkenes and Alkynes Similar physical properties to alkanes Undergo more reactions than alkanes Addition reaction: add compounds across double bond Importantly, they can form polymers Chapter 9

Aromatic Hydrocarbons Contain double or triple bonds, but do not show the same reactivity as other unsaturated hydrocarbons Benzene: C6H6 Used mainly as solvents Chapter 9

Chlorinated Hydrocarbons Add Cl to hydrocarbons Increase reactivity of alkanes Dissolve fats, oils, and greases Useful for dry cleaning Tend to accumulate in fatty tissues If toxic, this will be a problem Chapter 9

Chlorofluorocarbons and Fluorocarbons Tend to be either liquids or gases Completely inert Except in upper atmosphere O2 soluble in fluorinated compounds Temporary substitute for hemoglobin Chapter 9

Functional Groups Group of atoms that gives a family of organic compounds its characteristic chemical and physical properties Alkyl group: derived from alkane by removing a H R stands for alkyl group in general Chapter 9

Chapter 9

Alcohol Family –OH group Replace -e with -ol CH3OH, methanol, simplest Produced industrially Mainly a chemical intermediate Chapter 9

Made industrially and by fermentation C2H5OH, ethanol Made industrially and by fermentation Industrially produced alcohol has noxious substances added Small, simple alcohols tend to be toxic Chapter 9

Multifunctional Alcohols Several common alcohols have more than one –OH group Ethylene glycol: main ingredient in antifreeze Glycerol: used in lotions Ingredent in some explosives Chapter 9

Phenol –OH group on benzene ring First antiseptic Different chemical properties than other alcohols Behaves more like an acid First antiseptic Also causes skin irritation Chapter 9

Ethers Two alkyl groups attached to same O Used mainly as solvent Example CH3CH2-O-CH2CH3 Used mainly as solvent Little chemical reactivity Insoluble in water Highly flammable Chapter 9

Chapter 9

Aldehydes and Ketones Both contain carbonyl group (C=O) Aldehyde: R-CHO Ketone: R-CO-R’ Chapter 9

Common Aldehydes Change -e ending to -al Produced by oxidation of alcohols Formaldehyde – used as a preservative Larger ones used as fragrances Benzaldehyde – flavor in maraschino cherries Chapter 9

Common Ketones Change -e ending to -one Acetone most common ketone Used primarily as a solvent Produced by oxidation of alcohols Chapter 9

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Carboxylic Acid Contains C=O and –OH group on same carbon Change -e to -oic acid Acetic acid: acid in vinegar Chapter 9

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Esters Derived from carboxylic acids and alcohols Tend to be fragrant Methyl butyrate apple Ethyl butyrate pineapple Ethyl formate rum Methyl salicylate wintergreen Chapter 9

Amines Contain N May have 1, 2, or 3 alkyl or aromatic groups Most biological amines are amino acids Building blocks of proteins Chapter 9

Amides N bonded directly to carbonyl group Linkage that holds proteins together Chapter 9

Heterocyclic Compounds Ring compounds that have something other than C in the ring Occur in plants Alkaloids: basic in solution Examples: caffeine, morphine, cocaine Form basic structure of DNA Chapter 9