Organic Chemistry L3 Flashcards
If it were easy, it would be biology (euuuugh)
What are the two kinds of reactions alkenes undergo?
Addition and oxidation
If a colourless liquid alkene was mixed with a brown solution of Bromine (Br2), what observations would you expect to see?
I would expect to see the brown solution (colour from bromine) declolourise due to it decreasing in concentration, as it reacts with the colourless alkene to form a colourless haloalkane.
What are the four kinds of addition reactions alkenes can experience?
Halogenation,
Hydrogenation,
Halohydrogenation,
and hydration.
Does Halogenation require any reagents or conditions that deviate from standard conditions to proceed, what does it produce?
No,
Di-haloalkanes
Does hydrogenation require any reagents or special conditions, and what does it produce?
Yes, It requires a platinum catalyst.
It produces alkanes.
Does hydration of alkenes require any reagents, and what does it produce?
Yes, It requires concentrated sulfuric acid (H2SO4).
It produces alcohols.
Does halohydrogenation require any special reagents, and what does it produce?
No. It produces haloalkanes.
An alkene is mixed with acidified potassium permanganate. What reaction is taking place, what is produced, and what observations would you expect to see?
Oxidation is happening, a diol is produced, and I would expect to see the purple permanganate decolourise, as a colourless diol is produced.
What two reactions are used as tests for unsaturation (a double bond being present)?
Halogentation and oxidation with permanganate.
In both, decolourisation is a sign of an usaturated material being present.
What kinds of groups tend to attach the carbon in a haloalkane reactive site? (think of electron density)
Nucleophiles (negative groups are attracted to the partial positive charge, due to dipole created by halogen group)
What substitutions can occur to a haloalkane?
Amine substitution and hydroxyl substitution
What kind of haloalkane is most likely to undergo hydroxyl substitution (as opposed to elimination)?
Primary haloalkanes
What are the products of hydroxyl substitution with haloalkanes, and are any special conditions needed?
An alcohol and halide (which often forms a salt with whatever cation was bonded to the hydroxyl).
Normal, low temperature, and aqueous solution make it more likely, as well as non-concentrated hydroxide.
What are the products of amine substitution with halogens, and are any special conditions needed?
An amine and a halide are produced.
Conc. NH3 needed, and an alcoholic solvent.
What are the products of haloalkane elimination, and what conditons (and what kind of haloalkane) make it more likely?
An alkene, a halide, and a water molecule (a hydroxide that accepts another hydrogen) are produced.
Alcoholic conditions, high temperature, and conc. OH- make the conditions better, and a tertiary haloalkane is more likely to be eliminated.
What is Zaitzev’s rule in simple terms?
The poor get poorer (in terms of hydrogens)
Say you have a primary haloalkane, but don’t know specifically what kind of halogen is bonded on. You also had NaOH and water, as well as AgNO3 (silver nitrate). How could you distinguish between the products of a chloroalkane, a bromoalkane, or an iodoalkane?
Hydroxyl substitution will occur, and the halogen will turn to an uncombined halide. Silver salts are mostly insoluble (a precipitate will form), and a silver halide salt will form. A silver bromide salt will be off-white, a silver chloride salt will be white, and an silver iodide salt will be pale yellow.
Can tertiary alcohols undergo oxidation reactions? If so, what do they produce, and are any special conditions needed?
They do not undergo oxidation reactions
Can secondary alcohols undergo oxidation reactions? If so, what do they produce, and are any special conditions needed?
Yes. They produce ketones, and the mixture must be refluxed (ketones have a low boiling point)
Can primary alcohols undergo oxidation reactions? If so, what do they produce, and are any special conditions needed?
Yes. If a weak oxidant (like dichromate) is used and the mixture is distilled, an aldehyde can be produced. If a strong oxidant (like permanganate) is used and the mixture is refluxed, a carboxylic acid is produced.
What are the two ways to substitute the hydroxyl group on an alcohol with a halide?
There is using conc. hydro halide,
and using thionyl chloride
Which is the better way to turn an alcohol into a haloalkane, and why?
By using thionyl chloride, as more haloalkane is produced, and the other products are easier to separate.
What conditions are needed to get an alcohol to eliminate into an alkene?
Heat and conc. H2SO4 (no water)
What is the difference between conditons of the alcohol-alkene and alkene-alcohol reaction?
In the alkene-alcohol reaction, conc. H2SO4
AND H20.
In the alcohol-alkene reaction, conc. H2SO4
If I had a primary alcohol and I wanted an aldehyde, how would I get it?
React alcohol with dichromate in a distilling setup. The distillate will be an aldehyde.
What kind of alcohol is needed to produce a ketone?
A secondary alcohol.
What would be an effective test for the prescence of an amine?
Damp red litmus paper (the dampness (i.e. water) would cause the amine to form hydroxide ions, which would turn the paper blue). Amines are the only strongly basic functional group present at L3.