Topic 10.1: Fundamentals of Organic Chemistry Notes

Topic 10.1: Fundamentals of Organic Chemistry Notes

Terminology Hydrocarbon: compounds that contain mostly hydrogen and carbon Homologous Series: compounds with the same general formula Molecular Formula: shows the number of atoms only (C2H6O) Structural Formula: shows how the atoms are arranged Condensed: CH3CH2OH Empirical Formula: shows lowest whole number ratio of atoms

Examples: Homologous Series = CnH(2n+2) Molecular Formula = C4H10 Structural formula: Condensed S.F. = CH3CH2CH2CH3 Empirical Formula = C2H5

Homologous Series The general trend for all molecules in a homologous series is an increase in the boiling point. This is because of the effect of London Dispersion Forces and the molecular weights of the lengthening carbon chains

Structural Isomers Structural Isomer: same molecular formula but different structure Straight Chain- C4H10 CH3CH2CH2CH3 Branched Chain- C4H10 CH3CH2(CH2)CH3

s Definition: Atoms or groups of atoms attached to a hydrocarbon They are usually the reactive groups on a stable carbon chain so form the important part of the molecules Examples: Alcohols Aldehydes Ketones Carboxylic Acids Halides (Halogenoalkanes)

Class Name Alkanes Formula CnH2n+2 Name alkyl none Suffix -ane

Alkyl Groups Branches on carbon chains -CH3 -CH2CH3 methyl ethyl

IUPAC Naming Summary 1. Count the C s in the longest chain 2. Name each attached group 3. Count the longest carbon chain to give the first attached group the smallest number 4. Name and locate each group

Naming Branched Alkanes

Class Name Alkene Formula CnH2n Name alkenyl Suffix -ene

Alkenes Name Number of Carbons Condensed Structural Formula Ethene 2 CH2CH2 Propene 3 CH2CHCH3 Butene 4 CH2CHCH2CH3 Pentene 5 CH2CHCH2CH2CH3 Hexene 6 CH2CHCH2CH2CH2CH3

Naming Branched Alkenes 1. 2. 3. 4. 5. Select the longest chain of C atoms containing the double bond and number the chain from this end Place the ending -ene on the basic name Use a number to indicate the lower number carbon of the C=C bond As in alkanes, prefix with substituents Side chain positions are based on the number allocated to the first C of the C=C CH3- CH = CH - CH2- CH(CH3) - CH3 5-methylhex-2-ene

Structural Isomerism of Alkenes Different structures are possible due to.different positions for the double bond

Alkynes- very unstable Name Number of Carbons Condensed Structural Formula Ethyne 2 CHCH Propyne 3 CHCCH3 Butyne 4 CHCCH2CH3 Pentyne 5 CHCCH2CH2CH3 Hexyne 6 CHCCH2CH2CH2CH3

Class Name Alkyne Formula CnH2n-2 Name alkynyl Suffix -yne

Saturated vs. Unsaturated Saturated Hydrocarbons are hydrocarbons that contain no double or triple bonds (alkanes) - They are saturated with hydrogens Unsaturated hydrocarbons are alkenes and alkynes

Class Name Halogenoalkane Formula CnH2n+1X Name X= F, Cl, Br, or I Suffix none Prefix Fluoro-, chloro-, bromo-, iodo

Halides and Naming Different positions for the halogen and branching of the carbon chain 1-chlorobutane 2- chloro-2-methylpropane 2-chlorobutane 1- chloro-2-methylpropane

Halides The number of carbons that are joined to the carbon with the halogen group determine if it is a 1, 2, or 3 halide.

Will react differently due to shielding effects from the other carbons Tertiary 3

Class Name Alcohols Formula R-OH Name Hydroxyl Suffix -ol

Naming Alcohols Full Structural Formula Skeletal Structure Name Ethanol Propan-1-ol Propan-2-ol

Full Structural Formula Skeletal Structure Name Pentan-3-ol

Alcohols The number of carbons that are joined to the carbon with the alcohol group determine if it is a 1, 2, or 3 alcohol.

Class Name Ether Formula ROR Name Ether Suffix none Prefix -oxy-

Naming Ethers Methoxy methane 2-ethoxy-2-methylpropane

Class Name Aldehyde Formula RCHO Name Aldehyde Suffix -al

Naming Aldehydes Name Condensed Structural Formula Ethanal CH3CHO Propanal CH3CH2CHO Butanal CH3CH2CH2CHO Pentanal CH3CH2CH2CH2CHO

Class Name Ketone Formula RC(O)R Name Carbonyl Suffix -one

Naming Ketones Name Condensed Structural Formula Propanone CH3COCH3 Butanone CH3CH2COCH3 Pentan-2-one CH3COCH2CH2CH3 Pentan-3-one CH3CH2COCH2CH3

Class Name Ester Formula RCOOR Name Ester Suffix -oate

Naming Esters 1. Always take the carbon chain with the double bond as the initial stem. The side group is next to the single bonded oxygen. 2. Add -oate Methyl ethanoate Ethyl methanoate

Class Name Carboxylic Acid Formula RCOOH Name Carboxyl Suffix -oic acid

Carboxylic Acids Carboxylic Acids form a homologous series

Naming Carboxylic Acids 1. 2. 3. 4. 5. Select the longest chain of C atoms containing the COOH group Remove the e and add oic acid after the basic name Number the chain starting from the end nearer the COOH group As in alkanes, prefix with alkyl substituents Side chain positions are based on the C in COOH being 1 CH3- CH(CH3) - CH2 - CH2 - COOH 4-methylpentanoic acid

Class Name Amine Formula RNH2 (H=R) Name amino Suffix -amine

Happy News!! IB expects you to be familiar with the nitrogen containing functional groups (amines, amides, nitriles) but nomenclature of these classes of compounds will not be assessed

Naming Amines Nomenclature: Named after the groups surrounding the nitrogen + amine Name Condensed Structural Formula Ethylamine C2H5NH2 dimethyamine (CH3)2NH trimethylamine (CH3)3N

Class Name Amide Formula RCONH2 Name carboxamide Suffix -amide

Naming Amides Solids named from the corresponding acid Remove oic acid, add amide CH3CONH2 ethanamide C2H5CONHC6H5 N- phenyl propanamide The N tells you the substituent is on the nitrogen

Class Name Nitrile Formula RCN Name cyano Suffix -nitrile

Naming Nitriles Butanenitrile CH3CH2CH2C N Ethanenitrile CH3C N

Class Name arene Formula CnH2n-6 Name phenyl Suffix none

Benzene Due to the resonance energy or stabilization energy of benzene, it is reluctant to undergo addition reactions, but will undergo substitution reactions. Delocalization minimizes the repulsion between electrons

Physical Evidence for Benzene Stability X-Ray Bond Length Data (nm): Alkane Single Bond C-C 0.154 nm Alkene Double Bond C=C 0.134 nm Benzene 0.139nm

Naming Arenes Arenes are compounds with a benzene ring. Aliphatics on the other hand are compounds without a benzene ring such as alkanes and alkenes. 1,2- diphenylethyne Bromobenzene

Physical Characteristics of the s Explain volatility between functional groups H Bonding and Van der Waals (Dipole-Dipole and London Dispersion Forces) Explain Solubility- Need to be polar and small Ethanal CH2CHO (BP) 21 Soluble Propanal C2H5CHO (BP) 46 Slightly Soluble

Effects of lengthening chain and branching