Organic Chemistry: Introduction IB Topic 10

10.1 Introduction Describe the features of a homologous series Predict and explain the trends in boiling points of members of a homologous series Distinguish between empirical, molecular and structural formulas Describe structural isomers as compounds with the same molecular formula but with different arrangement of atoms Deduce structural formulas for the isomers of non- cyclic alkanes up to C Apply IUPAC rules for naming the isomers of the non-cyclic alkanes up to C 6.

What is organic chemistry? Organic Chemistry The study of carbon, the compounds it makes and the reactions it undergoes. The study of carbon, the compounds it makes and the reactions it undergoes. Over 16 million carbon-containing compounds are known. Over 16 million carbon-containing compounds are known.

What is organic chemistry? Carbon Carbon can form multiple bonds to itself and with atoms of other elements. Carbon can form multiple bonds to itself and with atoms of other elements. Carbon can only make four bonds since it has 4 valence electrons and most often bonds to H, O, N and S. Carbon can only make four bonds since it has 4 valence electrons and most often bonds to H, O, N and S. Because the C-C single bond (348 kJ mol - 1 ) and the C-H bond (412 kJ mol -1 ) are strong, carbon compounds are stable. Because the C-C single bond (348 kJ mol - 1 ) and the C-H bond (412 kJ mol -1 ) are strong, carbon compounds are stable. Carbon can form chains and rings. Carbon can form chains and rings.

What is organic chemistry? Hydrocarbons Hydrocarbons are organic compounds that only contain carbon and hydrogen Hydrocarbons are organic compounds that only contain carbon and hydrogen Types of hydrocarbons include Types of hydrocarbons include  Alkanes  Alkenes  Alkynes  Aromatic

10.1.1Describe the features of a homologous series. A homologous series is a series of related compounds that have the same functional group. Homologous compounds… A homologous series is a series of related compounds that have the same functional group. Homologous compounds… Differ from each other by a – CH 2 – unit (methylene group) Differ from each other by a – CH 2 – unit (methylene group) Can all be represented by a general formula Can all be represented by a general formula Have similar chemical properties Have similar chemical properties Have physical properties that vary in a regular manner as the number of carbon atoms present increases Have physical properties that vary in a regular manner as the number of carbon atoms present increases

# C Prefix Alkane (ane) C n H 2n+2 Alkene (ene) C n H 2n 1meth CH 4 methane 2eth C2H6C2H6C2H6C2H6ethane C2H4C2H4C2H4C2H4ethene 3prop 4but 5pent 6hex

10.1.2Predict and explain the trends in boiling points of members of a homologous series. What is the trend? Why? AlkaneFormula Boiling Pt./ o C methane CH ethane C2H6C2H6C2H6C2H propane C3H8C3H8C3H8C3H butane C 4 H

10.1.2Predict and explain the trends in boiling points of members of a homologous series. Intermolecular forces present Intermolecular forces present Simple alkanes, alkenes, alkynes → van der Waals’ forces (nonpolar) → lower b.p. Simple alkanes, alkenes, alkynes → van der Waals’ forces (nonpolar) → lower b.p. Aldehydes, ketones, esters & presence of halogens (polar) → dipole: dipole forces → slightly higher b.p. Aldehydes, ketones, esters & presence of halogens (polar) → dipole: dipole forces → slightly higher b.p. Alcohol, carboxylic acid & amine → hydrogen bonding (w/ O, N, F) → even higher b.p. Alcohol, carboxylic acid & amine → hydrogen bonding (w/ O, N, F) → even higher b.p.

10.1.2Predict and explain the trends in boiling points of members of a homologous series.

10.1.3Distinguish between empirical, molecular and structural formulas. Empirical Formula: Smallest whole number ratio of atoms in a formula Molecular Formula: Formula showing the actual numbers of atoms Molecular Formula Empirical Formula CH 4 C2H6C2H6C2H6C2H6 CH 3 C 6 H 12 O 6 C4H8C4H8C4H8C4H8 C 8 H 16

10.1.3Distinguish between empirical, molecular and structural formulas. Structural Formula Bond angles are drawn as though 90 o. The true shape around C with 4 single bonds is tetrahedral and the angle is o. Bond angles are drawn as though 90 o. The true shape around C with 4 single bonds is tetrahedral and the angle is o. Show every atom and every bond. Can use condensed structural formulas. Show every atom and every bond. Can use condensed structural formulas. Hexane: CH 3 CH 2 CH 2 CH 2 CH 2 CH 3 (condensed s.f.) Hexane: CH 3 CH 2 CH 2 CH 2 CH 2 CH 3 (condensed s.f.) M.F. = C 6 H 14 E.F. = C 3 H 7

10.1.3Distinguish between empirical, molecular and structural formulas.

10.1.4Describe structural isomers as compounds with the same molecular formula but with different arrangement of atoms. Isomers: different compounds that have the same molecular formula Isomers: different compounds that have the same molecular formula Structural isomers: an isomer in which the atoms are joined in a different order so that they have different structural formulae Structural isomers: an isomer in which the atoms are joined in a different order so that they have different structural formulae

10.1.4Describe structural isomers as compounds with the same molecular formula but with different arrangement of atoms.

10.1.5Deduce structural formulas for the isomers of non-cyclic alkanes up to C 6. If there is a branch off of the main chain, put that formula in parentheses If there is a branch off of the main chain, put that formula in parentheses CH 3 CH(CH 3 )CH 3 CH 3 CH(CH 3 )CH 3 CH 3 CH 2 CH 2 CH 3 CH 3 CH 2 CH 2 CH 3

10.1.5Deduce structural formulas for the isomers of non-cyclic alkanes up to C 6. Draw out and write the structural formulas for all isomers that can be formed by: Draw out and write the structural formulas for all isomers that can be formed by: CH 4 CH 4 C 2 H 6 C 2 H 6 C 3 H 8 C 3 H 8 C 4 H 10 C 4 H 10 C 5 H 12 C 5 H 12 C 6 H 14 C 6 H 14

Apply IUPAC rules for naming the isomers of the non-cyclic alkanes up to C Determine the longest carbon chain 2. Use the prefix (next slide) to denote the number carbons in the chain 3. Use the suffix “-ane” to indicate that the substance is an alkane 4. If the chain is branched, the name of the side chain will be written before the main chain and will end with “–yl”

Apply IUPAC rules for naming the isomers of the non-cyclic alkanes up to C 6. Methylpropane Methylbutane Dimethylbutane

1Meth-6Hex- 2Eth-7Hept- 3Prop-8Oct- 4But-9Non- 5Pent-10Dec-

For chains longer than 4 carbons with side chains: 5. Number the carbons in the chain consecutively, starting at the end nearest side chains. 6. Designate the location of each substituent group by an appropriate number and name. And with 2 or more side chains: 5. Use prefixes di-, tri-, tetra-, to indicate when there are multiple side chains of the same type. 6. Use commas to separate numbers and hyphens to separate numbers or letters. 7. Name the side chains in alphabetical order.

10.1 Introduction, cont Deduce structural formulas for the isomers of the straight- chain alkenes up to C Apply IUPAC rules for naming the isomers of the straight-chain alkenes up to C Deduce structural formulas for compounds containing up to six carbon atoms with one of the following functional groups: alcohol, aldehyde, ketone, carboxylic acid and halide Apply IUPAC rules for naming compounds containing up to six carbon atoms with one of the following functional groups: alcohol, aldehyde, ketone, carboxylic acid and halide Identify the following functional groups when present in structural formulas: amino (NH 2 ), benzene ring ( ) and esters (RCOOR) Identify primary, secondary and tertiary carbon atoms in alcohols and halogenoalkanes Discuss the volatility and solubility in water of compounds containing the functional groups listed in

10.1.7Deduce structural formulas for the isomers of the straight-chain alkenes up to C 6. Remember that structural formulas show the relative location of atoms around each carbon Remember that structural formulas show the relative location of atoms around each carbon Hexane: CH 3 CH 2 CH 2 CH 2 CH 2 CH 3 (condensed s.f.) Hexane: CH 3 CH 2 CH 2 CH 2 CH 2 CH 3 (condensed s.f.) M.F. = C 6 H 14 Determine the molecular formulas for the alkenes below. Draw out and write the structural formulas for all isomers that can be formed by each. Determine the molecular formulas for the alkenes below. Draw out and write the structural formulas for all isomers that can be formed by each. C 2 H 4 C 2 H 4 C 3 H ? C 3 H ? C 4 H ? C 4 H ? C 5 H ? C 5 H ? C 6 H ? C 6 H ?

Alkenes have one (or more) carbon to carbon double bonds Suffix changes to “-ene” When there are 4 or more carbon atoms in a chain, the location of the double bond is indicated by a number. Begin counting the carbons closest to the end with the C=C bond Numbering the location of the double bond(s) takes precedence over the location of side chains 1-butene 2-butene methylpropene Apply IUPAC rules for naming the isomers of the straight-chain alkenes up to C 6.

10.1.9Deduce structural formulas for compounds containing up to six carbon atoms with one of the following functional groups: alcohol, aldehyde, ketone, carboxylic acid and halide. Functional group = a group of atoms that defines the structure of a family and determines its properties Functional group = a group of atoms that defines the structure of a family and determines its properties

10.1.9Deduce structural formulas for compounds containing up to six carbon atoms with one of the following functional groups: alcohol, aldehyde, ketone, carboxylic acid and halide. Functional Group FormulaStructural Formula Alcohol-OH - O – H Aldehyde-COH (on the end of a chain) O - C – H Ketone- CO – (not on the end) O - C – Carboxylic Acid-COOH O - C – O – H Halide-Br, -Cl, -F, -I- X

Functional Groups

Apply IUPAC rules for naming compounds containing up to six carbon atoms with one of the following functional groups: alcohol, aldehyde, ketone, carboxylic acid and halide. Functional Group FormulaSuffix (or Prefix) Alcohol-OH -ol Aldehyde-COH -al Ketone- CO - -one Carboxylic Acid -COOH -oic acid Halide-Br, -Cl, -F, -IBromo-, chloro-, fluoro-, iodo-

Identify the following functional groups when present in structural formulas: amino (NH 2 ), benzene ring ( ) and esters (RCOOR). A few more groups: Functional Group Formula Amine- NH 2 Ester O R – C – O – R Benzene Ethyl ethanoate

Identify the following functional groups when present in structural formulas: amino (NH 2 ), benzene ring ( ) and esters (RCOOR). Esters are used for fragrances and flavoring agents since one of their major properties is smell Esters are used for fragrances and flavoring agents since one of their major properties is smell Benzene is in a family known as the aromatic hydrocarbons… because they smell Benzene is in a family known as the aromatic hydrocarbons… because they smell

Identify primary, secondary and tertiary carbon atoms in alcohols and halogenoalkanes. With reference to the carbon that is directly bonded to an alcohol group or a halogen: Primary = carbon atom is only bonded to one other carbon Primary = carbon atom is only bonded to one other carbon Secondary = carbon atom is bonded to two other carbons Secondary = carbon atom is bonded to two other carbons Tertiary = carbon atom is bonded to three other carbons Tertiary = carbon atom is bonded to three other carbons

Discuss the volatility and solubility in water of compounds containing the functional groups listed in Volatility: how easily a substance turns into a gas Volatility: how easily a substance turns into a gas The weaker the intermolecular force, the more volatile it is The weaker the intermolecular force, the more volatile it is So, is a nonpolar or polar substance more volatile? So, is a nonpolar or polar substance more volatile? Solubility: a solute’s ability to dissolve in a polar solvent (water) Solubility: a solute’s ability to dissolve in a polar solvent (water) The more polar a substance is, the more soluble it is The more polar a substance is, the more soluble it is

Discuss the volatility and solubility in water of compounds containing the functional groups listed in Volatility: Volatility: vdW › d-d › H vdW › d-d › H alkane › halogenoalkane › aldehyde › ketone › amine › alcohol › carboxylic acid alkane › halogenoalkane › aldehyde › ketone › amine › alcohol › carboxylic acid Solubility: Solubility: If the functional group is soluble (hydrogen bonded), it will be more soluble If the functional group is soluble (hydrogen bonded), it will be more soluble Solubility decreases as chain length increases Solubility decreases as chain length increases Smaller alcohols, aldehydes, ketones & carboxylic acids are typically soluble Smaller alcohols, aldehydes, ketones & carboxylic acids are typically soluble Halogenoalkanes are NOT soluble since they don’t form hydrogen bonds Halogenoalkanes are NOT soluble since they don’t form hydrogen bonds