L I D E. Chapter 6 Organic Chemistry CARBON. Carbon. Chemistry in Focus 3rd edition Tro

Transcription

1 Chemistry in Focus rd edition Tro Chapter 6 Organic Chemistry CARBON Of the millions of known compounds in our world, 95% have a single element in common CARBON. What is so special about carbon? Carbon mallest member, and only nonmetal, of Group Forms covalent bonds Forms single, double, and triple bonds Bonds to itself, forming rings

2 5 6 The study of carbon-containing compounds and their chemistry is called organic chemistry. The properties of carbon-containing molecules determine the properties of the substance they compose. Organic vs. norganic arly 800s Organic Came from living organisms Chemically fragile Unsuccessful synthesis vital force? norganic Came from the earth Chemically durable uccessfully synthesized by 9 th century chemists Urea ynthesized by Friedrich Wohler in 88 Organic, but synthesized from an inorganic compound ubsequent death of vitalism The idea that life was somehow beyond physical laws was proved wrong. iving organisms must follow the physical laws of the universe.

3 7 8 9 Organic Compounds Two Major Types of Organic Compounds Hydrocarbons Contain only carbon and hydrogen Functionalized Hydrocarbons Hydrocarbons that contain additional atoms or groups of atoms Both groups can be further divided into subfamilies. The Hydrocarbon Family Alkanes Only single bonds Alkenes One or more double bonds Alkynes One or more triple bonds Aromatic ix-carbon rings

4 0 Alkanes All carbon atoms connected by single bonds General molecular formula: C n H n+ implest is methane, CH ach atom attains an octet; molecular geometry of methane is tetrahedral. Polarity of Hydrocarbons Carbon-hydrogen bonds are mostly nonpolar but any polarity would be symmetrically arranged about the central carbon atom(s). Methane s tetrahedral geometry makes it a nonpolar molecule. All other hydrocarbons are nonpolar as well. Nonpolar substances are unable to mix with polar substances. tructural Formulas how the relative positions of atoms in a molecule Two-dimensional imilar to ewis structures but dashes represent bonding electron pairs Condensed structural formulas are compactly written structural formulas.

5 Propane Formulas 5

6 6 7 8 traight chain alkanes are named with a base name depending on the number of atoms in the carbon chain and the suffix ane. Naming The most important property of the alkanes is their flammability, the combustion reaction between oxygen and the alkane producing carbon dioxide and water.

7 9 0 aturation Alkanes are saturated; they contain the maximum number of hydrogen atoms per carbon atom. Alkenes and alkynes are unsaturated. They contain at least one double or triple bond, respectively. They have fewer hydrogen atoms per carbon atom than alkanes. Alkenes Flammable and nonpolar like alkanes ouble bond makes them more chemically reactive than alkanes by addition across the double bond Bananas exposed to ethene (ethylene) ripen quickly.

8 Alkynes ike alkenes, not commonly encountered directly thyne (acetylene) is used in welding torches. somers t is possible for organic compounds to share a molecular formula but have different structures based on the branching of the carbon chain. somers can differ in their physical and chemical properties.

9 5 6 7 Unsaturated somers Alkenes and alkynes exhibit isomerism based on the position of the multiple bond. Naming Hydrocarbons UPAC Recommendations Alkanes etermine the base name of the longest continuous carbon chain. Consider branches to be substituents of the base chain. Number the base chain beginning with the end closest to the first branch. Order the name: Number of the substituent followed by a dash Name of the substituent Base name of the compound When two or more substituents are present, number each and list them alphabetically. Use numbering system that contains the lowest possible numbers. For two or more substituents on the same carbon, use that number twice. Use prefixes to denote identical substituents.

10 8 9 0 Naming Alkenes and Alkynes imilar to alkanes except for the addition of a number at the beginning to indicate the position of the multiple bond(s) Kekule and Aromaticity arly structure elucidation Carbons tendency for bonds reamed that he saw chains of 6 carbon atoms as snakes One snake bit its own tail Proposed benzene as a ring of 6 carbon atoms tructure is still accepted today Update on Kekule s Benzene Ring Kekule proposed a ring containing alternating double and single bonds. The bonds in benzene have since been found to be all of the same length. ach bond is now considered to be midway between a double and a single bond. Modern representation is a circle within a hexagon.

11 Benzene tructures The Benzene Ring Particularly stable When the ring contains substituents it is called a phenyl ring. Also called aromatic ring due to the notable aroma of many compounds containing such a ring Two or more fused such rings make polycyclic aromatic hydrocarbons. Common xamples

12 5 6 Functionalized Hydrocarbons Basic hydrocarbon structures form a foundation for a major grouping of organic compounds. Contain additional atoms or groups of atoms nsertion of functional groups to a hydrocarbon dramatically alters its properties. Representing Functionality Compounds containing the same functional group are called a family. Generic symbolism is R-FG where R is the hydrocarbon part of the molecule and FG is the functional group. R-OH symbolizes the alcohols. Functional groups help organize and classify organic compounds. Chlorinated Hydrocarbons Found in pesticides, solvents, refrigerant liquids One or more chlorine atoms substitute for one or more hydrogen atoms ower flammability and reactivity than hydrocarbons

13 7 8 9 T Muller demonstrated effectiveness against insects and relative non-toxicity to humans. tability made it efficient. ramatically decreased malaria in many countries Muller awarded Nobel Prize in 98 Resistance and bioamplification led to T s ban. CFCs Chlorofluorocarbons are a subfamily of chlorinated hydrocarbons. Chemically stable... Until they reach the high-energy sunlight in the upper atmosphere Ozone destruction led to bans.

14 0 Alcohols General formula: R-OH Additional of the OH makes alcohols polar. ncreased intermolecular attractive forces makes alcohols liquids. Naming involves modifying the hydrocarbon name with an ending of ol. Alcoholic beverages Gasoline additive ugar fermentation CN depressant Adverse health effects thanol

15 5 sopropyl alcohol is commonly known as rubbing alcohol. Other Alcohols Methanol is toxic to the human liver. thanol is administered as an antidote. Aldehydes and Ketones Commonly found in pleasant flavors and aromas Contain the carbonyl group: Carbon double bonded to an oxygen atom Aldehydes General formula: RCHO, includes carbonyl group Named according to length carbon chain with the ending of al or aldehyde Methanal or formaldehyde Formulas Preservation of biological specimens

16 6 7 8 Ketones imilar to aldehydes but have two R groups with the carbonyl Names end in one Acetone is the simplest ketone. Formulas Nail polish removal Carboxylic Acids Commonly found in sour foods General formula: RCOOH One of these oxygen atoms is bonded as a carbonyl group, as in aldehydes and ketones.

17 sters sters have pleasant odors. General formula: RCOOR Named according to the relevant R groups and ending with ate thers thers contain the functional group O- General formula: ROR Named according to the two R groups and given the ending ether Amines Amines are organic compounds that contain nitrogen. General formula: NR Notable for disagreeable odors Named for R groups present and ending in amine Formerly used as an anesthetic