Chemistry Structure 3: Organic Chemistry

What kinds of things are made out of organic compounds?

Biological molecules, fossil fuels, synthetic materials

What are Aliphatic Compounds?

Straight chains of carbon without benzene rings

What are Aromatic Compounds

Unsaturated Compounds with benzene rings

What is an Electrophile?

Positive ions or electron deficient species that are attracted to electron filled areas and will accept electrons to form covalent bonds

What is a Nucleophile?

Negative ions or species with lone pairs of electrons that are attracted to electron deficient areas and will donate electrons to form covalent bonds

What are the trends in physical properties within the same homologous series?

• Lower members are more likely gases/liquids, higher members more likely solids

• More Carbon = Higher Boiling Point, Lower Volatility

• More Branches → Less contact between atoms → Weaker IMFs = Lower Boiling Point, Higher Volatility

What reactions can Alkanes undergo? (2)

Combustion and Halogenation

What carbon products are made in Complete vs. Incomplete Combustion?

Complete Combustion → CO₂ (Carbon Dioxide)

Incomplete Combustion → CO or C (Carbon Monoxide, Carbon)

Why are Alkanes not as reactive as other homologous series?

They have non-polar saturated C-C bonds, so they are stabler

What are the 3 steps of Halogenation?

Initiation, Propagation, Termination

What is Homolytic Fission? Heterolytic fission?

Homolytic fission involves breaking a covalent bond between 2 elements to make two free radicals that each retain one shared electron from the bond

Heterolytic fission is the same process but instead of radicals, two oppositely charged ions are formed because one atom retained more electrons (2) from the bond than the other

What can be used to illustrate the movement of electrons to form ions in Heterolytic fission?

Double headed arrows (since a PAIR of electrons are moving)

What is needed to start Initiation in Halogenation?

UV Light

What are the products of Halogenation (the first reaction in a series of propagation reactions)?

Halogenoalkane + Halogen Halide

What will happen to the color of a Bromine solution if it is mixed with an Alkane under the presence of UV light? Without UV light?

With UV → Orange Brown to Colorless

Without UV → Stays Orange Brown

What reactions can Alkene undergo? (6)

Electrophilic Additions, Hydrogenation, Halogenation, Halogen Halide Addition, Hydration, Polymerization

What is an Electrophilic Addition Reaction? What are its products?

When an alkene’s C=C bond breaks to create two new bonding positions, one per carbon → Creates Alkanes, Halogenoalkanes, Dihalogenoalkanes, Alcohol (depending on which electrophilic addition reaction)

What is Hydrogenation?

When an alkene’s C=C bond breaks to bond to hydrogen using heat + nickel as a catalyst → Creates Alkanes

What is Halogenation? What are its products?

A process of electrophilic addition when an alkene’s C=C bond breaks to bond to a halogen (diatomic) → Creates Dihalogenoalkanes

What happens to the color of halogens when they undergo halogenation?

The dihalogenoalkane that is formed will be colorless instead of brightly colored like halogens are

What can be used to illustrate the movement of electrons to form radicals?

Fish hook arrows (since ONE electron is moving)

What is a Halogen Halide Addition? What are its products?

An electrophilic addition reaction when an alkene’s C=C bond breaks to bond to a halide (Halogen + something less electronegative) → Creates Halogenoalkanes

What is Hydration? What are its products?

When an alkene’s C=C bond breaks to bond to H₂O → Creates Alcohols and requires Heat + H₂SO₄ as a catalyst for the reaction

What components are needed to start Hydration?

Heat + Concentrated Sulfuric Acid (H₂SO₄) as a catalyst

What is Polymerization?

When an alkene’s C=C bond breaks and the alkene is used as a monomer to build a polymer of repeating units (can also happen with other unsaturated molecules that aren’t alkenes)

What are three examples of polymers?

Poly(chloroethene) - PVC

Poly(tetrafluoroethene) - Teflon/PTFE

Polystyrene

What reactions can Halogenoalkanes undergo? (1)

Nucleophilic Substitution Reactions

What are Nucleophilic Substitution Reactions?

When a nucleophile (usually a negative ion) attacks the electron deficient carbon part of a halogenoalkane and replaces the halogen

What will happen between the nucleophile and the halogen of a halogenoalkane in a nucleophilic substitution reaction?

The negative part of the nucleophile (an ionic compound) will attach to the carbon chain from the halogenoalkane to replace the halogen, which leaves to bond to the positive part of the ionic compound that is left over (ex. CH3CH2BR + NaOH → CH3CH2OH + NaBr)

Why is the C-Halogen bond “electron deficient” in a Halogenoalkane?

The halogen atom is more electronegative than the carbon, so there is a partial positive charge on the C and partial negative charge on the Halogen → the carbon is said to be electron deficient

What reactions can Alcohols undergo?

Combustion, Oxidation, Condensation

What is Oxidation?

When acidified (H₂SO₄) Potassium Dichromate (K₂Cr₂O₇) is used to differentiate between different alcohols/create ketones, aldehydes, or carboxylic acid

What is Condensation? What are its products?

When an alcohol and a carboxylic acid react to form esters and water

What are 3 examples of condensation?

1. Amino acids during peptide bond formation

2. Turning salicylic acid into an ester during aspirin production

3. Turning -OH groups from morphine into ester groups during heroin production

What is the difference in the steps for oxidizing primary vs. secondary alcohols?

Primary Alcohols have two H attached to the hydroxyl group which each need to be removed → Two steps until fully oxidized into a carboxylic acid (or one step if under reflux)

Secondary Alcohols only have one H attached to the hydroxyl group that needs to be removed → One step until fully oxidized into a ketone

What is the difference in the products formed when primary, secondary, and tertiary alcohols are oxidized?

Primary Alcohols → Aldehydes → Carboxylic Acids

Secondary Alcohols → Ketones

Tertiary Alcohols → No reaction

What is the difference between the changes in the color of the acidified K₂Cr₂O₇ solution when reacting with primary, secondary, and tertiary alcohols?

Primary and Secondary Alcohols: Orange → Green

Tertiary Alcohols: No change, just Orange

What is Saponification?

When esters (fats) are hydrolyzed using Sodium/Potassium Hydroxide (lye) to produce carboxylic acid salts (soap) and an alcohol (glycerol)

What are the steps involved in Saponification?

1. Nucleophilic attack by hydroxide: The alkali used as a catalyst (NaOH) will attach to the ester because OH is a nucleophile, breaking the C=O bond of the ester.

2. Leaving Group Removal: The double bond is reformed after the leaving group containing the other O of the original ester leaves, forming a carboxylic acid

3. Deprotonation: The leaving group also takes an H from the carboxylic acid to form an alcohol, turning the carboxylic acid into a carboxylate ion

Which reaction is in the opposite order of Saponification?

Condensation (alcohols)

What are examples of compounds that are Nucleophiles? (have lone pairs of electrons available - electron rich)

H₂O, NH₃, Alcohols (OH group), Amines (C=O)

What are examples of compounds that are Electrophiles? (have partial charges - electron deficient)

Hydrogen Halides, Halogenoalkanes, Halogens (X₂)

What are the two tests you can use to distinguish Alkanes and Alkenes?

Bromine Water Test, Burn Test

What color is each halogen?

Fluorine - Pale yellow

Chlorine - Green Yellow

Bromine - Red/Orange Brown

Iodine - Violet

What is the difference between how alkanes and alkenes will react in a bromine water test?

Alkane + Bromine Water (without UV) → No reaction, solution is still orange brown

Alkene + Bromine Water → Reacts, color of solution goes from orange brown to colorless

What is the difference between how alkanes and alkenes will react in a burn test?

Alkanes will produce clean, blue flames

Alkenes will produce smokey flames from unburned carbon because they have a higher Carbon-Hydrogen ratio from their double bond

What is the general formula for complete combustion of a hydrocarbon?

C_xH_y+ (x+y/4)O₂ → XCO₂ + (y/2)H₂O

What is the general formula for the incomplete combustion of a hydrocarbon that forms carbon monoxide as a product?

C_xH_y+ (x/2+y/4)O₂ → XCO + (y/2)H₂O

What is the general formula for the extreme incomplete combustion of a hydrocarbon that forms carbon as a product?

C_xH_y+ (y/4)O₂ → XC + (y/2)H₂O