Organic backbones (a chain of carbon) can bear heteroatoms (any element other than carbon) as reactive sites

Functional groups are attached to the carbon chain

Ex: R-OH → an alcohol

Big Idea in Organic Chemistry

STRUCTUIRE CONTROLS FUNCTIONS

• Each functional group has predictable reactivity based on its structure

Organic Halides

• A compound of carbon and hydrogen in which one or more hydrogen atoms have been replaced by halogen atoms
  • Sometimes generalized as “X”
• They’re classified based on the carbon the halogen is attached to…
  • If the carbon is attached to another carbon, that carbon is PRIMARY (1°) ****and the halide is also 1°
  • If the carbon is attached to two other carbons, that carbon is SECONDARY (2°) and the halide is also 2°
  • If that carbon is attached to three other carbons, that carbon is TERTIARY (3°) and the halide is also 3°

Voice Notes:

• “R” is the short form of a Carbon chain
  • Used when chemists don’t generally care about the carbon chain
• In order to react in chemistry, two molecules collide with the right orientation and energy
  • ^Activation energy
• Primary halides are most reactive because they don’t have much e- to repel other molecules, and there is more room for other molecules to collide with it

TEXTBOOK READINGS pg. 32-37

The Cost of Air Conditioning Summary

• New car with air conditioning includes the price of the unit + air conditioning tax + possible environmental damage
• The late 1800’s refrigerators were cooled using toxic gasses
• They began searching for safer refrigerants because of the fatal accidents due to leaked coolants from the units in the 1920’s-30’s
• 1930, DuPont company manufactured Freon (a type of CFC) which was considered very safe
• In the 1970’s, large ozone holes were detected in the upper atmosphere. The Freon’s are inert in the lower atmosphere, but reactive in the upper atmosphere
• Automobile AC’s use over one third of the total amount of Freon in Canada, and about 10% of this is released into the atmosphere each year → so we are now searching, again, for a new chemical to meet the demand for inexpensive AC systems that also minimize environmental damage
• Two chemicals have been developed as a substitute to refrigerants: HCFC’s and HFC’s.
  • They differ from CFC’s in that they contain hydrogen atoms as well as carbon and halogen atoms.
  • These chemicals readily decompose and have less time to cause damage to the ozone layer
  • HCF’s are the preferred substitutes for CFC’s since they have no Chlorine (the element that is causing the damage in the ozone layer), while the HCFC’s do
  • However they do release CO2 during decomposition → a major greenhouse gas
• Since 1995, HFC-134a has been the most commonly used coolant and is used in all new automobile AC’s

Preparing Organic Halides

• Alkyl halides are produced in halogenation rxn’s with hydrocarbons
• Alkenes and Alkynes readily add halogens or hydrogen halides to their double and triple bonds
• Recall also that Markovnikov’s rule of “the rich get richer” applies when hydrogen halides are reactants, and must be considered in designing the synthesis of specific alkyl halides. These alkyl halides can then be transformed into other organic compounds.
• If we wanted to produce a halide of a benzene ring, we would need to arrange a substitution reaction with a halogen
• Further substitution can occur in the benzene ring until all hydrogen atoms are replaced by halogen atoms.

Naming Organic Halides

• When naming org halides, consider the halogen atom as an attachment on the parent hydrocarbon

Properties of Organic Halides

• Halogen atoms on a hydrocarbon chain or ring makes the molecule more polar
  • This is because halogens are more electronegative than C and H atoms → meaning carbon-halogen bonds are more polar than C-H bonds.
• The increased polarity of alkyl halides increases the strength of the I.M.F.’s
  • Meaning they have higher boiling points and are more soluble in polar solvents than hydrocarbons of similar size
• When organic halides are formed from halogenation of hydrocarbons, the product obtained is often a mixture of halogenated compounds. These compounds may contain 1, 2, 3, or more halogens per molecule
• The difference in boiling points enables us to separate the components of a mixture by procedures such as fractional distillation

Preparing Alkenes from Alkyl Halides: Elimination Rxn’s

• Alkyl halides can eliminate a hydrogen and a halide ion from adjacent carbon atoms, forming a double bond in their place → making it an alkene
  • We would need a hydroxide ion to do so
• The type of reaction in which atoms or ions are removed from a molecule is called an ELIMINATION REACTIONS
  • This rxn of alkyl halides is the most common method of preparing alkenes