How will you convert methane to the following: ?
(a) propane
(b) butane
(c) methyl butanoate
(d) ethanoic acid
(e) ethanol
(a) propane
(b) butane
(c) methyl butanoate
(d) ethanoic acid
(e) ethanol
2 Answers
Methane being as unreactive as any alkane to most reactions (having a pKa of about
From that point, we can get a bit more... original/creative.
MAKING PROPANE
Making propane is not extremely difficult from here; simply use a very strong lewis base like sodium hydride or sodium amide to deprotonate acetylene.
Then you can react that as a nucleophile with the alkyl halide (as an electrophile) you just made to generate methylacetylene, which reduces down to the alkane via
MAKING BUTANE
Simple modification of the above pathway: just replace the acetylene that you bring in from a separate source with methylacetylene, and you have introduced an extra carbon into the semi-final product.
In that case the triple bond is not on the terminal carbon but on carbon-2. Then the reduction to the alkane generates butane.
MAKING METHYL BUTANOATE
This one is quite a bit trickier. I ended up simply making methanol from methane, and making a carboxylic acid from a separate acetylene source.
From acetylene, we used the
Full oxidation (via chromic acid, for instance) generates the carboxylic acid.
Heating with the alcohol dehydrates the carboxylic acid and alcohol to combine them into the ester in a Fischer esterification.
To be honest, it's much easier to start from acetylene...
MAKING ETHANOIC ACID
With this I invoke the Grignard reaction, which I hope you've learned at this point; it's one of the first labs you do in organic chemistry 2. You wouldn't have prepared the Grignard reagent itself, but you would have used it on an alkyne.
Grignards essentially act as really strong, but water-sensitive nucleophiles (water can donate a proton, deactivating the super strongly-basic nucleophile). i.e.
Weak acid finishes off the reaction by easily donating a proton to the methyl anion and turning
MAKING ETHANOL
Take the ethanoic acid you made, and simply reduce it using
(A nice alternative that does stop at the aldehyde is lithium tri-tert-butoxyaluminum hydride.)
How about the following…
Explanation:
(a) Propane
(b) Butane
(c) Methyl butanoate
(d) Ethanol