Chapter 1 – Organic Compounds

Organic Chemistry

Study of carbon-based compounds

Carbon is in over 90% of all compounds

Each carbon atom can form 4 bonds

Carbon can bond together to form chains, rings, spheres, sheets and tubes

Carbon can form combinations of single, double and triple covalent bonds

Organic compounds generally form covalent bonds

Inorganic compounds generally form ionic bonds (ex. CO2, CO)

Organic compounds use H-bonding, London Dispersion Forces and dipole forces to explain properties

Molecules are relatively large, so reactions are slow and often yield unwanted by-products Functional Groups

____________________________________________________________________________

Organic compounds are classified according to the types of functional groups attached to the chain

These determine the physical properties (solubility, melting point, boiling point) and reactivity of the compounds

There are 3 main components of functional groups:

1. ________________________________________________________________________ Multiple bonds ↑ reactivity of molecules because double or triple bonds are

weaker (more easily broken) than single bonds between C atoms

2. ________________________________________________________________________ Creates polar bonds (resulting in ↑ intermolecular forces) leading to ↑ melting

and boiling points

3. ________________________________________________________________________ Causes an ↑ in melting and boiling points

Hydrocarbons

Molecules containing C and H atoms only

Can be divided into 4 general categories: 1. Aliphatic compounds 2. Aromatic compounds 3. Heterocyclic compounds 4. Halogenated hydrocarbons

1. Aliphatic Compounds

Contain single, double or triple bonds between atoms

C atoms may also form ring (cyclic) structures

_______________________________ o C chain has only single bonds o Compound is said to be _______________(has the maximum number of

hydrogen)

_______________________________ o C chain has one or more double bonds o Compound is said to be ________________

_______________________________ o Unsaturated C chain contains one or more triple bonds

2. Aromatic Compounds

Have a unique, planar (flat) ring structure

All are derivatives of the benzene molecule (C6H6)

Some have a pronounced odour

e- belong equally to all 6 C’s

3. Heterocyclic Compounds

Ringed compounds that contain one of more atoms other than C in the ring (O and N are most common)

Ex. pyrrole

4. Halogenated Hydrocarbons

H atom on the C chain is replaced by a halogen

Properties of Hydrocarbons

Relatively non-polar because only C and H are present and both have similar electronegativities o Low solubility in ________________ (like water) o Good solvents for other non-polar molecules

Main intermolecular interaction is ___________________________(attraction of electrons of one molecule to the nuclei of another molecule)

o Weak forces, so molecules are easily separated o _________________________ have fewer electrons and therefore _______________

van der Waals forces, so have lower melting and boiling points compared to larger molecules

______________________________ show same reactivity as open-chained compounds

As # of C ↓ in ring, reactivity generally ↑ due to bond angles and bond strain

Ex. propane vs. cyclopropane

Nomenclature of Hydrocarbons

1. Alkanes o Saturated hydrocarbons o Name ends in ____________ o Prefix is determined by the # of C’s in the main chain o Generally low reactivity o As molecular mass ↑, melting point and boiling point ↑ o ______________________ – functional group that occurs when one H is removed from

an alkane chain Ex. methane vs methyl

o Show structural isomerism beyond 3 C’s _____________________ – compound with the same molecular formula, but

different structural arrangement

o Rules for Naming Alkanes 1. Number the carbon atoms that will form the longest continuous chain 2. Arrange the numbering so that any side branches are placed at the lowest

numbered carbon 3. Name each branch and identify its location on the parent chain by the number of

the carbon at the point of attachment 4. Follow the format – (number of location)-(branch name)(parent chain) 5. When more than one branch is present, list them in alphabetical order 6. Identify more than one of the same functional group present with Greek prefixes,

and the numbers of each location (NOTE – Prefixes are not considered when alphabetizing)

7. When naming cyclic hydrocarbons, the carbon atoms forming the ring will be the parent chain and the prefix cyclo- is added to the parent hydrocarbon name

Sample Problems – Name the following compounds:

a.

b.

c.

Solutions:

a. __________________________

b. __________________________

c. __________________________

2. Alkenes

o Unsaturated hydrocarbon with at least one double bond o Name ends in _____________ o Must give the location of the double bond (lowest possible C in chain and is indicated by

the number of the C atom that begins the multiple bond) o Double bond takes precedence over functional groups when numbering C atoms o Presence and location of multiple double bonds is indicated by the prefixes di-, tri-, etc. o Generally more reactive than alkanes (due to double bond) o Melting point and boiling points ↑ with molecular mass

Sample Problems – Name the following compounds:

a.

b. Solutions:

a. _____________________________________

b. _____________________________________

Geometric Isomerism o Alkenes with similar formulas, but different arrangement of atoms o C-C bond is able to rotate freely, but C=C bond is very rigid o Groups attached to the C atoms of the double bond can be on the same side of the bond

(__________) or opposite sides (__________) Sample Problems – Name the following compounds:

a.

b. Solutions:

a. _________________________________

b. _________________________________

3. Alkynes o Unsaturated hydrocarbons with at least one triple bond o All names end with ____________ o Triple bond take precedence o Triple bond is linear o Boiling points ↑ with molecular mass o Very reactive (due to triple bond)

Sample Problem – Name the following compound:

Solution:

_________________________________________

4. Aromatic Compounds o Compounds based on the benzene ring structure o Benzene is not as reactive as unsaturated aliphatic compounds o A planar hexagon with resonance o e- are mobile and evenly distributed o Benzene ring is usually considered to be the parent chain and attached alkyl groups are

the branches o Use benzene as a root name o Functional groups are placed at lowest possible C number o If one methyl group is attached, the molecule is called methylbenzene o When 2 or more alkyl groups are attached we must use numbers of the lowest terms

Examples:

a. 1,2-diethylbenzene __________ or ________________________ b. 1,3-diethylbenzene __________ or ________________________ c. 1,4-diethylbenzene __________ or ________________________

Sometimes the benzene ring is a functional group on another parent chain - in this case the ring is called ____________________

NOTE: naphthalene is the 2 benzene rings fused together Sample Problem – Name the following compound:

Solution: ____________________________________________

5. Halogenated Hydrocarbons o Add the halogen prefix to the regular hydrocarbon chain

ex. ________________________________________________ o Indicate the halogen position with a number o Prefixes follow alphabetical order when more than one is present

o Ex. chloromethane

o Ex. dichloromethane

Alcohols Properties of Alcohols

Represented by ____________________________________ attached to the chain

Boiling points are higher than those of their parent alkanes due to their OH groups

o ________________________________________________________________________

Simple alcohols are more soluble in water (same reason as above)

In longer alcohols the hydrocarbon portion is non-polar

o ________________________________________________________________________

Hydroxyl groups are sites of reaction – able to be converted into other families of compounds depending on which isomer of alcohol is involved

Nomenclature of Alcohols

Named by removing the “e” at the end and adding “______”

Hydroxyl group is given the lowest C atom number Sample Problem – Name the following compound:

Solution: ___________________________________________

Ex. The two isomers of C3H7OH are:

2-propanol is also known as isopropanol, i-propanol or isopropyl alcohol

________________________________ o Hydroxyl radical is on terminal C o Ex. propanol

________________________________ o Hydroxyl radical is bonded to a C atom, which is bonded to another 2 C’s (has 2 other

C-C bonds) o Ex. 2-propanol

________________________________ o Hydroxyl radical is bonded to a C atom, which is bonded to another 3 C’s (has 3 other

C-C bonds)

o Ex. 2-methyl-2-propanol

Polyhydroxy Alcohols o When 2 or more hydroxyl groups are bonded to the parent chain o The suffixes –diol and –triol are added to the entire alkane name to indicate the number

of OH groups

______________________________ o Name given to dihydroxy alcohols when OH groups are on neighbouring atoms

Cyclic Alcohols o Cyclic compounds with OH groups attached

o Simplest in this group is ________________________ or _______________________ Phenol is a colourless solid, slightly soluble in water (due to OH group), used in

industrial preparation of plastics, drugs, dyes and weed killers o When naming, the OH group may be considered as a group attached to the parent ring

Ethers Properties of Ethers

Structure is R-O-R (where _____________________________)

Alkyl groups may be identical or different

No OH groups so they do not form hydrogen bonds

_______________________________________________________________________ o Molecules are more polar than hydrocarbons

Good solvents o C-O bonds are polar so can dissolve polar substances o Alkyl groups can dissolve non-polar substances

C-O bonds are hard to break so ethers are unreactive (another property of a good solvent)

Intermolecular attractions between ether molecules are stronger than hydrocarbons, but weaker than those in alcohols

Nomenclature of Ethers Trivial Name

Name 2 alkyl groups and add “ether” at the end

When the two alkyl groups are the same, the prefix –di is used

______________________________________________________________________________

Ex. dimethyl ether

Ex. ethyl methyl ether Systematic (IUPAC) Name

Identify the longest C chain

Add “oxy” to the end of the name of the shortest alkyl group, and put it in front of longest alkyl group name

Ex. methoxymethane

Ex. methoxyethane

Naming Ethers as Branches When the ether is a branch of a longer chain, they are named as branches using the suffix “-oxy” Consider the following ether:

An ethyl group is attached to a longer carbon chain by an O atom, creating an ether. Name it as a branch. Name the rest of the molecule as you would, following the IUPAC rules of priority. Name - _____________________________________ Sample Problems – Name the following compounds:

a.

b.

Solution:

a.____________________________________________________

b.____________________________________________________

Aldehydes and Ketones Properties of Aldehydes and Ketones

Both contain _____________________________________________________________

Aldehydes – C=O is at the end of the carbon chain

Ketones – C=O is in the middle of the carbon chain

C=O is a strong polar group so they are more soluble in water than hydrocarbons

Good solvents because they mix with both polar and non-polar substances

Lower boiling points than analogous alcohols and are less soluble in water

o _____________________________________________________________________

Nomenclature of Aldehydes

Replace the “e” from the alkane name with “_________”

The carbonyl C is always at C #1, therefore no need to number the aldehyde position

Ex. Nomenclature of Ketones

Replace the “e” from the alkane name with “_________”

The location of the carbonyl group is numbered only when there are 5 or more carbon atoms in the C skeletal chain

The position of the carbonyl is given the lowest possible number over all others

Ex.

Carboxylic Acids Properties of Carboxylic Acids

Contain a _________________________

Are generally weak acids

Due to C=O and OH groups, these molecules are polar and can form H bonds with each other and water

Smaller acids have similar solubility to alcohols, but larger ones are relatively insoluble

Have higher boiling points due to intermolecular attraction between the carboxyl functional groups

Are found in citrus fruits, crab apples, rhubarb, and other food known by their sour tangy taste

Fatty Acids – carboxylic acid with 4-24 C atoms

Nomenclature of Carboxylic Acids

Replace the “e” from the alkane name with “_________________”

The C atom in the carboxyl group is included in naming the skeletal chain

Ex.

When naming acids with multiple COOH groups, use ______________________ when COOH’s are at each end of the parent chain

o Ex. ethandioic acid

The simplest aromatic acid is phenylmethanoic acid, also known as benzoic acid

Sample Problems – Name the following compounds:

a. b. Solution a. _________________________________________ b. _________________________________________

Esters Properties of Esters

Have the general formula or RCOOR’

Generally sweet smelling

Compared to carboxylic acids, the functional group is similar but has a “OR” group instead of an “OH”

o Therefore, esters are ______________________________________________________ ________________________________________________________________________than their parent acids

Nomenclature of Esters

The first part of the name comes from the alkyl group attached to the oxygen (R1)

The second part comes from replacing “ic acid” with “_________” Sample Problems - Name the following compounds:

a.

b.

c.

d. Solutions:

a. ________________________________

b. ________________________________

c. ________________________________

d. ________________________________

Amines and Amides

Properties of Amines and Amides

Contain nitrogen

Amines o Are like NH3 with 1, 2, or 3 of its H’s replaced with alkyl groups

o Are classified as __________________________________________________________

o Have higher boiling points and melting points than hydrocarbons of the same size o Smaller amines are soluble in water due to N-C and N-H bonds (both are polar)

Amides o Similar to esters but have an N atom replacing the O atom o Functional group consists of a carboxyl group attached to an N atom

o Weak bases o Insoluble in water o Small amides are slightly soluble in water

_________________________________________________________________ o Amides whose N atom is bonded to 2 H atoms have higher melting and boiling points

than amides that have alkyl groups attached because there is an increase of H bonding Nomenclature of Amines

Can be named in 2 ways: o As a nitrogen derivative of an alkane (IUPAC system)

ex. CH3NH2 would be __________________________________ o As an alkyl derivative of ammonia

ex. CH3NH2 would be __________________________________

Molecules with 2 amino groups are called diamines; ex. 1,5-diaminopentane

IUPAC names for 2º and 3º amines include the N- prefix to denote the substituted groups on the N atom of the amino group

Sample Problems - Name the following compounds:

a.

b. Solutions:

a. ___________________________________________________________

b. ___________________________________________________________ Nomenclature of Amides

Similar to naming esters

First part comes from the alkyl group attached to the N

Second part comes from the name of the acid, but remove the “-oic acid” from the name and add “______________”

Ex. When more than one alkyl group is attached to the N in the amide linkage, must use N- to clarify the

location of the group

Ex. Sample Problems – Name the following compounds:

a.

b.

c. Solutions:

a. __________________________________________________

b. __________________________________________________

c. __________________________________________________

IUPAC Functional Group Priority

Here is a list of the more important functional groups arranged in decreasing priority order for a nomenclature perspective. This priority order is important in nomenclature as the higher priority group is the principle functional group and it is typically numbered such that is has the lowest number

Functional Group

Formula

Carboxylic Acids

Acid Anhydrides

Esters

Acyl Halides

Amides

Nitriles

Aldehydes

Ketones

Alcohols

Thiols

Amines

Ethers

Sulphides

Alkenes

Alkynes

Alkyl Halides Nitro

Alkanes