L1 Hydrocarbons: Alkanes, Alkenes, Alkynes

Organic Compounds

Carbons based compounds

Isomer

Same molecular formula and number of atoms, but different structure

Hydrocarbon

A compound that contains only hydrogens and carbons

Saturated Hydrocarbons

Contain the maximum number for hydrogens, with single bonds between all carbons

Unsaturated Hydrocarbons

Contain one or more double or triple bonds (not seen in diagram but it causes molecule to kink or bend)

Aliphatic

Carbons arranged in chains

Cyclic

Carbons arranged in rings

Aromatic

Contain a benzene ring

Alkane Definition

Hydrocarbons with only single bonds between carbon atoms

Alkane General Formula

C_nH_2n+2

Alkene Definition

Hydrocarbon with at least one double bond

Alkene General Formula

C_nH_2n

Alkyne Definition

Hydrocarbon with at least one triple bond

Alkyne General Formula

C_nH_2n-2

Explicit Hydrogens

Hydrogens required to fill carbons valence, usually left out of hydrocarbon drawings

Hydrocarbon root name pneumatic

Monkeys Eat Peeled Bananas, meth-, eth-, Prop-, but-

Naming Alkanes

Based off of longest C chain, 1. Count longest C chain, 2. Determine root, 3. Add suffix “ane”

Naming Branched Alkanes

Based off of longest C chain, 1. count C in longest chain, 2. Determine root, 3. Use numbered C to give branches a position number, add “yl” suffix, 4. Add suffix “ane”

More rules for naming branched alkanes

1. Number from the end that will result in the lowest number of branches

2. Name branches alphabetically if there are more than one present

3. Add prefixes, di, tri, tetra… if there is more than one of the same branch

4. Commas between numbers, hyphens between numbers and letters

Substituent

A group attached to a parent chain or ring that replaces a hydrogen atom

What happens when an alkane appears as a substituent

Named by dropping the “ane” ending and replacing it with “yl”

How is the position of the substituent group determined

The numbering of the chain starts at the end closest to the branch, the substituent group is then labelled based off which C atom it is off of

How is the Alkane named

The location and name of substituent is followed by root alkane name

How are multiple substituents listed

Alphabetical order (not including prefixes), if there are many of the same substituent, then prefixes get attached, di, tri, tetra…

Practice naming the following

Summary of Steps for naming

1. Determine longest chain and find root name of hydrocarbon

2. If alkane group appears as substituent group, replace the “ane” with “yl” and keep root name

3. Number the chain s.t. the chain starts at the closest branch

4. Location, then name, of substituent group is followed by root name of alkane, note the substituents are named in alphabetical order (excluding prefixes), more than one of the same substituent is named using di, tri…

Naming Cyclic Alkanes

Add prefix “Cyclo” to the entire name of the alkane

First step of naming Alkenes and Alkynes

Count the longest possible C chain with the double/triple bond (parent chain), should be numbered s.t. the double/triple bond has the lowest number

The rest of the steps

2. Identify position numbers of branches (same as before)

3. Write branches in alphabetical order

4. Write the root, including prefix to identify position of double/triple bond (add prefix cyclo if cyclic)

5. Suffix “ene” for double bond, “yne” for triple bond, add di, tri… if there is more than one double/triple bond, diene…

Benzene

Cyclic 6 carbon ring of alternating single and double bonds

Naming Aromatics

Same rules except:

1. If benzene is parent chain, add suffix, “Benzene”

2. If benzene is branch group, add suffix “Phenyl”

Cis/Trans Isomers (Stereoisomers)

Formed when different groups of atoms are arranged around a double bond

Requirements for Cis/Trans Isomer

Each carbon in the carbon-carbon double bond must be attached to two different groups

Cis Isomer

Two larger groups are attached to each C=C on the same side

Trans isomer

Two larger groups are attached to each C=C on the opposite side

Naming Halo-alkanes/alkenes/alkynes

Same rules as a side chain, for halogens: first part of halogen and O, fluoro, chloro, bromo…

How is this often represented

R - X, where R= any hydrocarbon chain and x= halogen

Substituents to know

There are many we must know:

Name this One

n-propyl (normal propyl)

Name this One

Isopropyl (propan-2-yl)

Name this One

n-butyl (normal butyl)

Name this One

s-butyl (butan-2-yl) (secondary butyl)

Name this One

Isobutyl (2-methylpropan-1-yl or 2-methylpropyl)

Name this One

t-butyl (tert-butyl or 2-methylpropan-2-yl)

Prioritize double bond or substitutient

Double bond