Alkanes!(and alkyl halides)

The Saturated Hydrocarbons

The Saturated HC’s-alkanes

• Have only single bonds

• Also called the “paraffin compds”– Paraffin is an older term meaning “of little

activity”

• Alkanes are also saturated-meaning?

• Completely full of stuff– Diaper demo

Fossil Fuels• These are dead plants/animals that decay into a mixture of solid, liquid, and gaseous HC’s• Natural gas and petroleum are fossil fuels-usually found together• What are they good for?

– Sources of NRG (fireplace story)– Informative video with relaxing hypnotizing background music-10 min– http://videos.howstuffworks.com/hsw/17472-power-up-fossil-fuels-video.htm– Making plastics, drugs, synthetic fibers

• Putting old tires in pavement video 1.3 min• http://videos.howstuffworks.com/hsw/18903-enviro-tacklebox-phoenix-and-asphalt-rubber-video.ht

m

• Asphalt Rockets– Tim’s movie here– http://timpickens.com/– Buzz Aldin and Snoop Dog video http://www.youtube.com/watch?v=HcUeGRpPzgw– The making of the video

– http://www.youtube.com/watch?v=la4uPBqgQlc

Fossil fuels cont’d

• Coal– Coke-artificially made pure coal– Anthracite-hard coal-purest in nature– Bituminous-contains sulfur (glove story)– Lignite-brown coal, smoky flame– Peat-partially decomposed organic matter

• Dirty Jobs Video on coal mining 5 min– http://videos.howstuffworks.com/discovery/30930-dirty-j

obs-coal-mining-video.htm

• Or maybe this one’s better 5 min– http://videos.howstuffworks.com/science-channel/34261-h

ow-do-they-do-it-coal-mining-video.htm

Life-saving canaries

• Don’t write all this• Coal mines are breeding

grounds for methane and carbon monoxide, which are hazardous to human health, as well as conducive to deadly explosions. Before methane or carbon monoxide detectors existed, miners brought canaries down into coal mines with them. If a canary died, it was a sign of the presence of noxious gases and meant it was time to high tail it out of there.

Preparation of Alkanes

• Exodus story

• *Israel has no oil!

• Alkanes are so abundant in nature that there’s no need to make them in lab

• Instead they are collected/purified for use

Petroleum Refining!

• Petroleum in its(*) natural state is worthless

• It can be made into useful products by refining

• See residue

• Refining videos 10 min

• http://www.youtube.com/watch?v=jk0WrtA8_T8

• The 1st 10 alkanes• represented by the formula CnH2n+2 See board

• Know the 1st 10 alkanes-name, molecular formula, and structural formula-also recognize expanded and condensed forms

• Q: Why are none of these alkanes solids?• A: b/c they have very low freezing/melting

pts-most are liquids or gases• Q: which is more gaseous-ethane or

pentane?• Bpts and mpts increase with # of C’s

N and Iso Alkanes

• alkanes that form a continuous unbranched chain are called normal or n-alkanes

• Give exs• iso-alkanes have one branched C (on the second

C) • 4 kinds of carbons

– Primary, secondary, tertiary, quaternary– Normal alkanes have only primary and 2ndy C’s– Iso-alkanes have at least one 3rd or 4th degree C– Ex: isopropyl acohol

Naming Alkanes

• IUPAC naming rules!– Find longest continuous C chain, give it a base

name (ex: propane, pentane)– Identify side groups

• halogens-chloro, bromo, iodo, fluoro

• alkyl groups-methyl, ethyl, propyl

– Assign prefixes, alphabetize, use lowest #’s

• Naming cycloalkanes

Chemical Reactions of Alkanes

•   Oxidation=combustion=burning

• General pattern for oxidation reactions is:

• HC + oxygen carbon dioxide + water + heat

• EX: methane + oxygencarbon dioxide + HOH 

Exs of Combustion Rxns

• CH4 + 2O2 CO2 + 2H2O

• C3H8 + 5O2 3CO2 + 4H2O

• http://videos.howstuffworks.com/discovery/29392-assignment-discovery-combustion-video.htm 2 min lady w/boring voice

• The ratio of O to C is very impt

• W/out enough O2, you get CO instead of CO2

• Ex: car engine

• So why would that be bad? 3 min video– http://www.youtube.com/watch?

v=lchtRTDsHSM

What CO does in the body• Blood loves CO 200x> than O2

• Blood exposed to CO is less able to pick up and distribute O2

• Symptoms of CO poisoning:– Headaches– Nausea– Death– http://www.youtube.com/watch?v=QfuZuWpO7KY 9 min

• CO poisoning stories– Skyline Acres– Prostitutes

• The 2nd Chemical Rxn of Alkanes

• 2.    Substitution-sometimes you can sub a halogen for a hydrogen in an alkane making an alkyl halide

• Ex rxn on board

• Alkyl halides are very reactive

• Represented by "RX" (not "rxn")

• Specific alkyl halides: – Bromomethane or methyl bromide

• Berries from the west coast are made by forcing CH3Br into the soil

• ground is covered w/plastic to keep gas from escaping, then crops are planted

• Huge berries are b/c CH3Br kills worms, fungi, dogs, cats, & Mexicans

• Mexicans?!

• The govt plans to ban methyl bromide

• Why?– b/c it’s an ozone depletor

• Many crops depend on CH3Br

• It’s also used in termite fumigation-houses covered in plastic-kills termites, rats, and vagrants

• Alternatives to methyl bromide– http://www.youtube.com/watch?v=TOe8NJYQ

lAE

• “Chloromethanes”• CH3Cl-chloromethane-a good liquid solvent

• CH2Cl2-dichloromethane-A good refrigerant

• CHCl3-trichloromethane (chloroform)• Was once used in non-alcoholic pediatric cough

syrups• CCl4-carbon tetrachloride• Excellent spot remover for dry cleaning, but

carcinogenic, killed Chinese laundry workers

• others• CF2Cl2 Dichlorodifluoromethane-Freon• A refrigerant that’s completely unreactive• Heat causes it to vaporize-goes into condenser, is liquified

and reused.– Olan story

• It’s also a good propellant b/c it’s unreactive• How ac’s work- video

http://videos.howstuffworks.com/howstuffworks/1-how-air-conditioners-work-video.htm

• Freon escapes into the stratosphere where it’s zapped w/UV light and removes Ozone (O3)

• O3 is like a screen that protects us from UV light-too much UV light can cause cancer

• Chloroethane-see board

• Used as a cold spray to deaden skin before injections

• Used by athletic trainers-deadens pain by cooling when players are hurt

• also used to ripen fruit

• In Israel, nanner trees are covered w/bags to help the nanners ripen faster