Chapter 24 Organic Chemistry 24.1 Classes of Organic compounds 24.2 Alphatic hydrocarbons Alkane cycloalkane Alkenes Alkynes Aromatic hydrocarbon Chemistry of functional groups Alcohol , ethers , aldhyde and ketones ,carboxylic acid , esters Dr.Laila Al-Harbi

24.1 Classes of Organic compounds The chemistry of carbon compounds. Carbon has the ability to form long chains and ring structure. Dr.Laila Al-Harbi

24.2 Alphatic hydrocarbons Alkanes have the general formula CnH2n+2 where n = 1,2,3,… only single covalent bonds (C-C), sp3 hybridization saturated hydrocarbons because they contain the maximum number of hydrogen atoms that can bond with the number of carbon atoms in the molecule. Boiling point increase with increase molecular size because of the increasing dispersion. Dr.Laila Al-Harbi

24-2 Dr.Laila Al-Harbi

Alkanes Nomenclature IUPAC International Union of Pure and Applied Chemistry. each name consist of 3 parts prefix indicates position (1,3,…etc.) , number (di,tri, tetra …etc.) and type of branches (alkyl or substituent groups table 24-3) parent indicates the length of the longest carbon chain or ring suffix indicates the type of hydrocarbon ane, ene, yne Dr.Laila Al-Harbi

24-2 Dr.Laila Al-Harbi

CH3 CH CH2 1 2 3 4 5 4-methylpentane 1 2 3 4 5 2-methylpentane CH3 CH Use prefixes di-, tri-, tetra-, when there is more than one alkyl branch of the same kind. CH3 CH CH2 1 2 3 4 5 6 CH3 CH C CH2 1 2 3 4 5 6 2,3-dimethylhexane 3,3-dimethylhexane Dr.Laila Al-Harbi

2-bromo-5-methylhexane CH3 CH CH2 Br 2-bromo-5-methylhexane CH3 CH Br 1 2 3 4 NO2 2-bromo-3-nitrobutane CH2 3-bromo-1-nitrobutane The substituent group are listed alphabetically Dr.Laila Al-Harbi

Dr.Laila Al-Harbi

Dr.Laila Al-Harbi

What is the IUPAC name of the following compound? CH3 CH CH2 C2H5 1 2 3 4 5 6 7 8 4-ethyl-2-methyloctane What is the structure of 2-propyl-4-methylhexane? 1 2 3 4 5 6 CH3 CH CH2 C3H7 Dr.Laila Al-Harbi

DRAWING ORGANIC MOLECULES Molecular formulae: A molecular formula simply counts the numbers of each sort of atom present in the molecule, but tells you nothing about the way they are joined together. Example: the molecular formula of butane is C4H10, and the molecular formula of ethanol is C2H6O. Structural formulae: A structural formula shows how the various atoms are bonded. ethanoic acid would be shown in a fully displayed form and asimplified form as: Dr.Laila Al-Harbi

Structural Isomers in Alkanes Dr.Laila Al-Harbi

Example 24.1 How many structural isomers does pentane, C5H12, have? H n-pentane 2,2-dimethylpropane C H CH3 2-methylbutane Dr.Laila Al-Harbi

Reactions of Alkanes Alkane not very reactive 1-Combustion ( exothermic) CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (l) ∆H0 = -890.4 kJ 2C2H6 (g) + 7O2 (g) → 4CO2 (g) + 6H2O (l) ∆H0 = -3119 kJ 2- Halogenations CH4 (g) + Cl2 (g) CH3Cl (g) + HCl (g) light If an excess of chlorine gas is present, the reaction can proceed further: CH3Cl(g) + Cl2(g) → CH2Cl2(l) + HCl(g) methylene chloride CH2Cl2(l) + Cl2(g) → CHCl3(l) + HCl(g) chloroform CHCl3(l) + Cl2(g) → CCl4(l) + HCl(g) carbon tetrachloride Dr.Laila Al-Harbi

Cycloalkanes Alkanes whose carbon atoms are joined in rings are called cycloalkanes. The general formula is Cn H2n where n = 3,4,… ( cycloalkane) Dr.Laila Al-Harbi

Alkenes 2-butene 1-butene Cracking Geometric isomers of alkenes Alkenes have the general formula CnH2n where n = 2,3,… (sp2) contain at least one carbon-carbon double bond ( also called olefins) CH2 CH CH3 CH3 CH 2-butene 1-butene Cracking C2H6 (g) CH2 = CH2 (g) + H2 (g) Pt catalyst Geometric isomers of alkenes cis-dichloroethylene trans-dichloroethylene C Cl H C Cl H Dr.Laila Al-Harbi

Which of the following compounds has geometrical isomer ? Cl C H Cl NO ,Geometrical isomer NO ,Geometrical isomer C NO2 Cl H C NO2 Cl H yes ,it has geometrical isomer NO ,Geometrical isomer C Cl H yes ,it has geometrical isomer Dr.Laila Al-Harbi

Alkenes Reactions Addition Reactions CH2 = CH2 (g) + Br2 (g) → CH2B - CH2Br (g) CH2 = CH2 (g) + HBr (g) CH3- CH2Br (g) Symmetrical alkene unsymmetrical alkene Dr.Laila Al-Harbi

Alkynes Alkynes have the general formula CnH2n-2 where n = 2,3,4,… contain at least one carbon-carbon triple bond (sp) CH3 C CH C CH2 CH3 2-butyne 1-butyne Production of acetylene CaC2 (s) + 2H2O (l) → C2H2 (g) + Ca(OH)2 (aq) Alkynes Reactions 3-oxidation 1-Hydrogenation CH ≡ CH (g) + H2 (g)→ CH2 ≡CH2 (g) 2C2H2 (g) + O2 (g)→ 4CO2 +2H2O 2-Addition Reactions 4-decomposition CH ≡ CH (g) + HBr (g) → CH2 ≡ CHBr (g) C2H2 (g) → 2C(s) + H2 (g) CH ≡CHCH3 (g) + HBr (g) → CH2=CHCH3 (g) Br - Dr.Laila Al-Harbi

Aromatic Hydrocarbons Aromatic compound contain one or more benzene ring C H Aromatic Compound Nomenclature If one H atom has been replaced by another atom or a group of atom >>the name of the atom or group then benzene CH2CH3 Cl chlorobenzene NH2 NO2 nitrobenzene ethylbenzene aminobenzene Dr.Laila Al-Harbi

Aromatic Compound Nomenclature If more than one substituent is present >>we must indicate the location of the second group relative to first then benzene Br Br Br 1 2 3 4 5 6 Br 1,2-dibromobenzene 1,3-dibromobenzene 1,4-dibromobenzene o-dibromobenzene m-dibromobenzene p-dibromobenzene NO2 Br CH3-CH-CH3 m-bromonitrobenzene 2-phenylpropane Dr.Laila Al-Harbi

Aromatic Compound Reactions 1- Substitution reaction H Br + HBr + Br2 FeBr3 catalyst H CH2CH3 + HCl + CH3CH2Cl AlCl3 catalyst 2- hydrogenation Pt catalyst Dr.Laila Al-Harbi

25.3 Proteins Polymers are large molecules made up of repeating units called Monomers Proteins are polymers of amino acids ; they play a key role in nearly all biological process. Proteins high molar mass; ranging from about 5000 g. The basic structural unit of protein is amino acids Amino acid is a compound that contains at least one amino group(-NH2) and at least one carboxyl group(-COOH) Dr.Laila Al-Harbi

Structure – an amino acid possesses both a carboxyl and an amino group. The most common in the biological amino acids are the a-amino acids. The amino acid exists as a dipolar ion , possessing both a positive charge and a negative charge. Dipolar ion 20 different amino acids are the building blocks of all proteins in the human body The amino group of one molecule condenses with the acid group of another to gives Protein through peptide bonds Dr.Laila Al-Harbi

Functional Group Chemistry Term used to refer to parts of organic molecules where reactions tend to occur. Compounds Functional gp. Comments 1-alcohol R-OH 2-Ethers R-O-R’ R=R’ , R≠ R’ R (Hydrocarbon , aromatic ) 3-ketone 4-aldhyde 5-carboxilic acid 6- ester 7- amine R3N R2NH , RNH2 8-Amino acid R - C – R’ O = R - C - H O = R - C - OH O = R - C – OR’ O = R-CH - C - OH O = NH2 - Dr.Laila Al-Harbi

Classify each of the following molecules as alcohol, aldehyde, ketone, carboxylic acid, amine, ether or amino acid. Dr.Laila Al-Harbi