Alkanes vs. Alkenes

What do you think these words mean? Homologous Series Saturated Hydrocarbons Unsaturated Hydrocarbons A group of compounds whose chemical formula increases by one carbon atom from one compound in the series to the next Ex: CH4, C2H6, C3H8… Hydrocarbons with all single bonds, any alkanes Hydrocarbons without all single bonds, any alkenes or alkynes

Melting and Boiling Point Look at the regular Chem text page 753 What pattern do you see in boiling point as alkanes get more carbons? What pattern do you see as molecules get less saturated? More carbons = higher boiling point Less saturated = more double bonds = lower boiling point… mostly

Melting Point cont. Put these in order of increasing melting point: Ethane Octane Butane 1-Octene Ethane < Butane < 1-Octene < Octane

Solubility Summary: Alkanes and Alkenes are both NOT soluble in water. Plus, they are less dense than water. Alkane Alkene Water with green food color

Alkanes burn cleaner than Alkenes Combustion Black Smoke Summary: Alkanes burn cleaner than Alkenes Alkene Alkane Blue Flame

Alkane <-> Alkene Alkane  Alkene is called cracking Alkene  Alkane is called addition C3H8 heat and Ni catalyst C3H6 + H2 C3H6 + H2  C3H8

Identifying Alkanes/enes Alkane + Halogen  Haloalkane (slow), substitution Alkene + Halogen Haloalkane (fast) this is called addition C3H8 + Br2  C3H7Br + HBr C2H4 + Br2  C2H4Br2

Bromine- Substitution and Addition Reactions Plain Br2 reference Alkene Alkene Alkane Alkane Plain Br2 reference Summary: Alkenes react quickly with Br2- addition Alkanes react slowly + need UV light- substitution

Quick Review Alkanes and alkenes are ____ soluble in water As # of C increases, melting point ____ As saturation decreases, melting point ____ Combustion of _____ is cleaner than _____ Alkanes change into alkenes with _____ and _____ Alkenes turn into alkanes with _____ An ____ reacts quickly to decolorize Br2 NOT increases decreases alkanes alkenes heat Nickel catalyst hydrogen alkene

We need fat in our diet To… Cholesterol too Absorb shock, warmth, energy, move electrical/nerve currents, construct membranes, brain function, sex glands, hormone function Cholesterol too Can be from food, but our body makes all we need Hormones, steroids, skin protectant, antioxidant “Good cholesterol”= HDL, “Bad” = LDL Click here…

Saturated Fats Avoid Them! Animal products + coconut and palm oils, peanuts, butter Solids at room temperature and body temperature Can stack up on each other because the structures are floppy, even form crystal structures (aggregate) Insoluble in water What they can do that’s bad: Deposit within cells, organs, arteries, and under skin In arteries = atherosclerosis which hardens arteries and increases blood pressure Make blood platelets stickier which = blood clots clot to brain = stroke, clot to heart = heart attack Decrease blood oxygen supply because red blood cells stick together and are less mobile Increase bad (LDL) cholesterol and block the effects of good (HDL) cholesterol Interfere with insulin function Avoid Them!

Oils This shows the result when different butters and oils are combined with bromine. Which brand has the most saturated fat? Which has the least? So… Coconut oil is the worst and Wesson “best blend” is the best Most Unsat. Fat Most Sat Fat

Unsaturated Fats Monounsaturated Polyunsaturated Have a very slight + and – charge, so they repel each other, keeping them fluid (liquid at room and body temperature) and unable to aggregate like saturated fats Less stable (more likely to oxidize, turn rancid) than saturated fats From 1 to 6 double bonds Monounsaturated Decrease bad (LDL, which sticks to the walls of your arteries) cholesterol and increase good (HDL, which is essential to your body function + prevents inflammation of arteries) Olive oil, canola oil, avocado, nuts, butter Polyunsaturated Decrease the bad (LDL), but don’t effect the good Omega fatty acids (increase brain function + heart health) O-3 means that the fat has a double bond at C3 O-6 means that it has one at C6 Cold water fish, almonds, walnuts, leafy veggies, flax, hemp, safflower, + brains, eyes, and testes of animals (which is why those parts were prized by primitive hunter-gatherer people)

Cis vs. Trans

Trans Fats Artificially created unsaturated fat, “partially hydrogenated” changes a cis double bond into a trans Much more stable than unsaturated fats, but still just as cheap Margarine, shortening, fried food, packaged food Why are they bad? The trans bond increases the melting point above room and body temperature, so they are solids Essentially they act like saturated fats (boooo!) Make blood platelets sticky = clots and artery blockage Block the function of good fats by blocking enzymes which convert EFAs into the fats our brain uses Hurt the barrier around cells so some molecules can enter cells though they normally could not = decreased immune function, allergic reactions, cancers Interfere with electrical currents Block functions of prostaglandins which regulate blood pressure, clotting, kidney function, and the immune system Decrease testosterone and increase abnormal sperm Correlated to obesity, high cholesterol, heart disease and cancer Avoid Them!

FATS SATURATED UNSATURATED Mono Poly Trans Animal fats Tropical oils Avocados, Olives, Nuts Poly Flax, Hemp, Nuts, Fish, Sunflower, Canola Trans Margarine, Shortening + Packaged foods