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Classification of Organic CompoundsClassification of Organic CompoundsIndex of Hydrogen Deficiency number of pairs of H atoms that must be added to the molecular formula of a compound to make it saturated= 1 per double bond= 1 per ring= 2 per triple bond2Classification of Organic Compounds3Alkanesare compounds that contain only CC and CH bondsgenerally come from fossil fuels, particularly natural gas and crude oilFormula is always CnH2n+2

Natural gas is usually a mixture of small alkanes with low boiling points (methane, ethane, and propane). Crude oil, on the other hand, contains alkanes of all sizes that are then separated through a process called fractional distillation, during which compounds are separated by their boiling points.4Structural FormulasAlkanes are written with structural formulas that areexpanded to show each bond (Lewis Structure).condensed to show each carbon atom and hydrogen atoms attached to that carbon.

Expanded (Lewis) Condensed H H C H CH4 , methane

H55In methane, CH4 the four valence electrons of carbon are shared with the single electrons of four hydrogen (H) atoms. Each pair of electrons is a single bond, which can be drawn as a line. When a structure is drawn to show each bond, it is called a complete structural formula.Expanded and Condensed Structures

6Structural Formulas Condensed formulas are written for expanded structural formula by showing each carbon and the attached hydrogen atoms. Expanded Condensed H H H H HC C C C H CH3CH2CH2CH3 H H H H

7Alkane Nomenclaturethe names of all organic compounds stem from the names of the alkanes

Natural gas is usually a mixture of small alkanes with low boiling points (methane, ethane, and propane). Crude oil, on the other hand, contains alkanes of all sizes that are then separated through a process called fractional distillation, during which compounds are separated by their boiling points.8Alkane NomenclatureStraight chain alkanes are alkanes in which all the carbon atoms line up in a row.Called unbranched or normal

Natural gas is usually a mixture of small alkanes with low boiling points (methane, ethane, and propane). Crude oil, on the other hand, contains alkanes of all sizes that are then separated through a process called fractional distillation, during which compounds are separated by their boiling points.9Alkane NomenclatureUnbranched/ Normal Alkanes# CName#CName1Methane11Undecane2Ethane12Dodecane3Propane13Tridecane4Butane14Tetradecane5Pentane15Pentadecane6Hexane16Hexadecane7Heptane17Heptadecane8Octane18Octadecane9Nonane19Nonadecane10Decane20EicosaneAlkane Nomenclature

Condensed Structural FormulaActually Zig-Zag StructuresAll Carbons sp3 HybridizedAlkane NomenclatureName the smaller rows that branch off of the larger rows as if they were little independent alkanes of their own, better known as alkyl groups.As youve probably guessed, not all alkanes have all of their carbon atoms lined up in a nice row. As a result, weve got to consider what happens when these nice rows have other nice rows that branch off of them.12Alkane Nomenclature

Hexane or n-hexaneAlkyl group: MethylAs youve probably guessed, not all alkanes have all of their carbon atoms lined up in a nice row. As a result, weve got to consider what happens when these nice rows have other nice rows that branch off of them.13Alkyl Group NomenclatureUnbranched Alkyl Groups# CName#CName1Methyl11Undecyl2Ethyl12Dodecyl3Propyl13Tridecyl4Butyl14Tetradecyl5Pentyl15Pentadecyl6Hexyl16Hexadecyl7Heptyl17Heptadecyl8Octyl18Octadecyl9Nonyl19Nonadecyl10Decyl20EicosylAlkane NomenclatureThe carbons in an alkane are sometimes classified by how many other carbon atoms are stuck to them.Though its not intuitively obvious at this point why we would want to do this, it turns out to beuseful later because its often related to chemical reactivity.1516Alkane NomenclatureClassified by the connection sitea carbon at the end of a chain (primary alkyl group)a carbon in the middle of a chain (secondary alkyl group)

17Alkane NomenclatureClassified by the connection sitea carbon with three carbons attached to it (tertiary alkyl group)a quaternary (4) carbon atom has four other carbon atoms bonded to it.

Alkane Nomenclature

Alkane Nomenclature

butyl group or n-butylAlkane Nomenclaturesec-butyl group

Alkane Nomenclaturetert-butyl group

Alkane NomenclatureTo name alkanes, we use the system thats approved by the International Union of Pure and Applied Chemistry (IUPAC) for just this purpose.Though its not intuitively obvious at this point why we would want to do this, it turns out to beuseful later because its often related to chemical reactivity.22Alkane NomenclatureTo name alkanes, we use the system thats approved by the International Union of Pure and Applied Chemistry (IUPAC) for just this purpose.Though its not intuitively obvious at this point why we would want to do this, it turns out to beuseful later because its often related to chemical reactivity.23Alkane Nomenclature: Rule 1The root name for an alkane is based on the longest unbroken chain of carbon atoms (called the parent chain).

Derivative of heptaneBecause the longest unbroken carbon chain in this molecule contains sevencarbon atoms (shown in bold), this molecule is a derivative of heptane.24Alkane Nomenclature: Rule 1aWhen there are two longest chains of equal length, use the chain with the greater number of substituents as the main chain.Because the longest unbroken carbon chain in this molecule contains sevencarbon atoms (shown in bold), this molecule is a derivative of heptane.25CH3

CH3CHCH2

CHCHCH2CH3

CH3CHCH3

CH3

Which is correct?

Correct, 7-Carbon chain w/ 4 substituentsAlkane Nomenclature: Rule 2Assign numbers to each of the carbon atoms in this chain, beginning with the side thats nearest the first point of branching.Correct numbering

Because the second drawing has a lower-numbered carbon at the first branchingpoint (the methyl at the 3 position as opposed to the ethyl at the 4 position), thenumbering in the second molecule is correct.28Alkane Nomenclature: Rule 3Identify the names of the substituent groups and number them according to their position on the chain.

4-ethyl3-methylBecause the longest unbroken carbon chain in this molecule contains sevencarbon atoms (shown in bold), this molecule is a derivative of heptane.29Alkane Nomenclature: Rule 4Write the names of the substituents alphabetically, followed by the name of the parent alkane.

4-ethyl-3-methylheptaneIn our case, we have the substituents 3methyl and 4ethyl and the parent alkaneis heptane. Putting it together, this molecule is named 4ethyl-3methylheptane(with no space between the 3methyl and heptane). All substituent names are separatedfrom each other with dashes.30Another example!

2,3-dimethylhexaneHopefully you can see that the longest chain has six carbon atoms. If we numberthe carbon atoms correctly, we will start from the end closest to where the substituentsbranch off (which results in their being at the 2- and 3positions). Because bothgroups contain one carbon, they are named the 2methyl and 3methyl groups.Now, you might think that this compound should be called 2methyl-3methylhexane,but youd be wrong. Whenever we have more than one substituent that has the samenumber of carbon atoms, we can combine them by using di-, tri-, tetra-, and penta- toindicate how many of this group are present. Numbers indicating the positions of thesubstituent branches are separated by a comma. As a result, this molecule is properlynamed 2,3dimethylhexane.2,3dimethylhexane31More Problems!Problem 1: Write the name of the compound here.

Problem 2: Draw the 2,3,4trimethylheptane molecule.

More Problems!Problem 3: Write the name of the compound.

More Problems!If the numbers turn out the same way numbering it in both directions, the correct way to number it is by putting the alphabetically first substituent at the position with the lowest number.

Correct numberingAs you can see, if you number the carbon atoms in one direction, you have the substituents3methyl and 4ethyl, while if you number it the other way, you get the3ethyl and 4methyl substituents.34More Problems!Problem 3: Write the name of the compound.

3ethyl-4methylhexaneCH3

CH3CHCH2

CHCHCH2CH3

CHCHCH3

CH3

Which is correct?

Correct, 7-Carbon chain w/ 4 substituentsCH3

CH3CHCH2

CHCHCH2CH3

CH3CHCH3

CH3

Derivative of heptane3-ethyl-2,4,5-trimethylheptane

More ProblemsGive the structures:4-isopropyloctane5-tert-butyldecane.4-isopropyloctane

5-tert-butyldecane

HaloalkanesHaloalkanes can be named just like alkanes, with the halogen atom treated as a substituent. Halogen substituents are named fluoro-, chloro-, bromo-, and iodo-.When more than one halogen is present in the parent chain, they must be named alphabetically.43Haloalkanes

2-bromobutane

1,2-difluoropropane44Complex SubstituentsComplex alkyl groups are named by a systematic method using the longest alkyl chain as the base alkyl group.The base alkyl group is numbered beginning with the carbon atom (the head carbon) bonded to the main chain.45Complex SubstituentsThe substituents on the base alkyl group are listed with appropriate numbers, and parentheses are used to set off the name of the complex alkyl group.

A (1-ethyl-2-methylpropyl) groupA propyl groupNatural gas is usually a mixture of small alkanes with low boiling points (methane, ethane, and propane). Crude oil, on the other hand, contains alkanes of all sizes that are then separated through a process called fractional distillation, during which compounds are separated by their boiling points.46Complex Substituents

3-ethyl-5-(1-ethyl-2-methylpropyl)nonaneA propyl groupNatural gas is usually a mixture of small alkanes with low boiling points (methane, ethane, and propane). Crude oil, on the other hand, contains alkanes of all sizes that are then separated through a process called fractional distillation, during which compounds are separated by their boiling points.475-(1,2,2-trimethylpropyl)nonane48