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10 General, Organic, and Biochemistry, 8e Bettelheim, Brown, Campbell, and Farrell © 2006 Thomson Learning, Inc. All rights reserved 10-1 10 Chapter 10 Organic Chemistry © 2006 Thomson Learning, Inc. All rights reserved 10-2 10 Organic Chemistry • Organic chemistry: the study of the compounds of carbon. • Organic compounds are made up of carbon and only a few other elements. • chief among these are hydrogen, oxygen, and nitrogen • also present are sulfur, phosphorus, and halogens (fluorine, chlorine, bromine, or iodine) © 2006 Thomson Learning, Inc. All rights reserved 10-3 10 Organic Chemistry • Why is organic chemistry a separate discipline within chemistry? • Historical: scientists at one time believed that a “vital force” present in living organisms was necessary to produce an organic compound. • The experiment of Wöhler in 1828 was the first in a series of experiments that led to the demise of the vital force theory. NH4 Cl + AgNCO A mmonium Silver ch loride cyan ate © 2006 Thomson Learning, Inc. All rights reserved heat O H2 N-C-NH2 + AgCl U rea Silver chloride 10-4 10 Organic Chemistry • The sheer number of organic compounds • Chemists have discovered or made over 10 million organic compounds and an estimated 100,000 new ones are discovered or made each year. • By comparison, chemists have discovered or made an estimated 1.7 million inorganic compounds. • Thus, approximately 85% of all known compounds are organic. • The link to biochemistry • Carbohydrates, lipids, proteins, enzymes, nucleic acids, hormones, vitamins, and almost all other chemicals in living systems are organic compounds. © 2006 Thomson Learning, Inc. All rights reserved 10-5 10 Organic Chemistry • a comparison of organic and inorganic compounds Organi c Comp ound s Ino rg an ic Co mpou nds Bond ing is almost entirel y co val ent May be g ases, li quid s, o r so li ds w ith l ow melti ng po ints (l ess than 360°C) Mo st are i nsol ubl e in w ater Mo st are so lu ble i n o rg an ic so lv en ts such as d iethy l ether, to luene, and dichl orometh ane Aqu eo us so lutio ns do n ot condu ct el ectrici ty Al most all burn M ost have i oni c bo nds M ost are sol id s w ith h ig h melting po in ts Reacti ons are usuall y sl ow Reactio ns are o ften very fast © 2006 Thomson Learning, Inc. All rights reserved M any are so lu ble i n w ater A lmo st al l are i nso lubl e in o rgani c so lvents A queous sol uti ons cond uct electrici ty V ery f ew burn 10-6 10 Organic Structure • Structural formula: shows the atoms present in a molecule as well as the bonds that connect them. • VSEPR model: the most common bond angles are 109.5°, 120°, and 180°. HH HH H C C H-C C-H H H Eth ylen e (bond angles 120°) Acetylene (bond an gles 180°) H-C-C-Cl : HH Ch loroeth ane (bond angles 109.5°) H : : : : : : H H H H-C-N-H H-C-O-H C O H H HH Methanol Formald ehyde Methan amin e (b ond angles (bond angles (bond angles © 2006 Thomson Learning, Inc. 109.5°) 120°) 109.5°) All rights reserved : : H-C-C-H HH Eth ane (bond angles 109.5°) H C N H H Methyleneimine (bond angles 120°) 10-7 10 Organic Structure • Among neutral (uncharged) organic compounds: • Carbon: normally forms four covalent bonds and has no unshared pairs of electrons. • Hydrogen: forms one covalent bond and no unshared pairs of electrons. • Nitrogen: normally forms three covalent bonds and has one unshared pair of electrons. • Oxygen: normally forms two covalent bonds and has two unshared pairs of electrons. • Halogen: normally forms one covalent bond and has three unshared pairs of electrons. © 2006 Thomson Learning, Inc. All rights reserved 10-8 10 Functional Groups • Functional group: an atom or group of atoms within a molecule that shows a characteristic set of predictable physical and chemical properties. • Functional groups are important because • They undergo the same types of chemical reactions no matter in which molecule they are found. • To a large measure they determine the chemical and physical properties of a molecule. • They are the units by which we divide organic compounds into families. • They provide the basis on which we derive names for organic compounds. © 2006 Thomson Learning, Inc. All rights reserved 10-9 10 Functional Groups • Six common functional groups Family Functional group Example Name Alcohol - OH CH3 CH2 OH Ethanol Amine CH3 CH2 NH 2 O CH3 CH O CH3 CCH3 O CH3 COH Ethanamine Carboxylic acid - NH2 O - C- H O - CO - C- OH Carboxylic ester O - C- OR O CH3 COCH 2 CH 3 Aldehyde Ketone © 2006 Thomson Learning, Inc. All rights reserved Ethanal Acetone Acetic acid Ethyl acetate 10-10 10 Alcohols • Alcohol: contains an OH (hydroxyl) group bonded to a tetrahedral carbon atom. For example, ethanol: : R R-C-O-H R Function al group (R = H or carbon goup : HH H-C-C-O-H HH S tructural formula CH3 CH2 OH Cond ensed stru ctural formu la • may be primary (1°), secondary (2°), or tertiary (3°) H CH3 -C-OH H A 1° alcohol © 2006 Thomson Learning, Inc. All rights reserved H CH3 -C-OH CH3 CH3 -C-OH CH3 A 2° alcohol CH3 A 3° alcoh ol 10-11 10 Alcohols • Problem: draw Lewis structures and condensed structural formulas for the two alcohols with the molecular formula C3H8O. © 2006 Thomson Learning, Inc. All rights reserved 10-12 10 Alcohols • Problem: draw Lewis structures and condensed structural formulas for the two alcohols with the molecular formula C3H8O. • Solution: Cond ensed stru ctural : : Lew is stuctu res HH H H-C-C-C-O-H HH H formulas CH3 CH2 CH2 OH A p rimary alcohol H H:O: H OH H C-C-C-H HH H CH3 CHCH3 A secon dary alcohol © 2006 Thomson Learning, Inc. All rights reserved 10-13 10 Amines • Amine: a compound containing an amino group. • the amino group may be primary (1°), secondary (2°), or tertiary (3°). CH3 NH2 CH3 NH or (CH3 ) 2 NH Methylamin e (a 1° amine) CH3 D imethylamin e (a 2° amine) © 2006 Thomson Learning, Inc. All rights reserved CH3 NCH3 or (CH3 ) 3 N CH3 Trimethylamin e (a 3° amine) 10-14 10 Amines • Problem: draw condensed structural formulas for the two primary amines with the molecular formula C3H9N. © 2006 Thomson Learning, Inc. All rights reserved 10-15 10 Amines • Problem: draw condensed structural formulas for the two primary amines with the molecular formula C3H9N. • Solution: NH2 C-C-C-NH2 C-C-C Th e three carbon s may be bond ed to n itrogen in tw o w ays © 2006 Thomson Learning, Inc. All rights reserved CH3 CH2 CH2 NH2 NH2 CH3 CHCH3 Add s even hydrogens to give each carbon four b on ds an d give the correct molecu lar formula 10-16 10 Aldehydes and Ketones • Both contain a C=O (carbonyl) group. • Aldehyde: contains a carbonyl group bonded to a hydrogen; in formaldehyde, the simplest aldehyde, the carbonyl group is bonded to two hydrogens. • Ketone: contains a carbonyl group bonded to two carbon atoms. RO R C-C-H O CH3 CH R Fun ctional A cetaldeh yde grou p (an aldehyde) © 2006 Thomson Learning, Inc. All rights reserved RO R O R C-C-C R CH3 CCH3 R R Functional group Acetone (a ketone) 10-17 10 Aldehydes and Ketones • Problem: draw condensed structural formulas for the two aldehydes with the molecular formula C4H8O. © 2006 Thomson Learning, Inc. All rights reserved 10-18 10 Aldehydes and Ketones • Problem: draw condensed structural formulas for the two aldehydes with the molecular formula C4H8O. • Solution: • First draw the functional group of an aldehyde and add the remaining three carbons; these may be bonded in two ways. • Then add the seven hydrogens necessary to complete the four bonds of each carbon. O CH3 CH2 CH2 CH or CH3 CH2 CH2 CHO © 2006 Thomson Learning, Inc. All rights reserved O CH3 CHCH CH3 or CH3 CHCHO CH3 10-19 10 Carboxylic Acids • Carboxylic acid: a compound containing a -COOH (carboxyl: carbonyl + hydroxyl) group. • In a condensed structural formula, a carboxyl group may also be written -CO2H. O O CH3 COH RCOH Fu nctional Acetic acid group (a carb oxylic acid ) © 2006 Thomson Learning, Inc. All rights reserved 10-20 10 Carboxylic Acids • Problem: draw a condensed structural formula for the single carboxylic acid with the molecular formula C3H6O2 © 2006 Thomson Learning, Inc. All rights reserved 10-21 10 Carboxylic Acids • Problem: draw a condensed structural formula for the single carboxylic acid with the molecular formula C3H6O2 • Solution: the only way the carbon atoms can be written is three in a chain; the -COOH group must be on an end carbon of the O chain. CH3 CH2 COH or CH3 CH2 COOH © 2006 Thomson Learning, Inc. All rights reserved 10-22 10 Functional Groups • Carboxylic ester: a derivative of a carboxylic acid in which the H of the carboxyl group is replaced by a carbon group. O C-O–C Functional group © 2006 Thomson Learning, Inc. All rights reserved O CH3 -C- O-CH3 or CH3 COOCH3 or CH3 CO 2 CH 3 Methyl acetate (an ester) 10-23 10 Chapter 10 Organic Chemistry End Chapter 10 © 2006 Thomson Learning, Inc. All rights reserved 10-24