Home Podcasts THMG111 – Functional groups (Alcohols)

THMG111 – Functional groups (Alcohols)


We are continually going through the different functional groups and their effects. This is Bob’s favorite by far…the alcohols.

Thanks for listening and watching!

Thank you to FirstLine Tech and Rigaku for their support.

There is a second part of nomenclature that understanding can benefit us all from. and that is functional groups
• What is a functional group
– these are a group of atoms that when attach to a saturated carbon atom or organic molecules function in a similar way. They’re called hydroxyl groups
• The most common example of this would be alcohol. Alcohol is a functional group that is comprised of an O and H together attached to a carbon molecule.
– Ethanol or grain alcohol is the one we know the best. Let’s break down this word and see what it is.
• Eth so 2 carbons
• an so single bond
• ol so it has an OH functional group
• C2H5OH
The oh in the alcohol give alcohol the similar solubility as water
You might see this as hydrophilic or water-loving
The addition of the function group doesn’t make it miserable it only increase its solubility
In smaller molecules the solubility becomes 100%
We see this in methane to methanol
Propane to propanol (rubbing alcohol)
However, in bigger molecules the OH starts to become weaker and weaker when compared to the larger nonpolar partner
Think of it like this. Magnets are attracted to each other right? So let take 100 pieces of 1-inch piece of wood and glue a magnets on the end of them. We would be able to get these piece of wood to stick to each other. Now let make the piece of wood bigger. As these pieces become bigger there is less likely chance that a magnet will find another magnet on the wood. So less and less of the wood will stick together. This is the same conceptual idea
The OH group also has the ability to increase the boiling temp.
This is also related to the function of the OH group very similar to solubility
In solubility the magnetism allow everyone to play in the sandbox
But the fact that OH has these van der Waal forces or hydrogen bonding also keeps the alcohol sorta connected together. This means it takes more energy to get the molecules to get into the atmosphere. Hence needed a higher temperature to get them to vaporize.
Methane and propane are gasses but propanol and methanol are liquids
This is good because it also means that they have lower vapor pressures than their parent carbon chains.
Flammability tends to run just like solubility. Smaller OH tend to be more flammable than larger OH.
The longer the carbon chain the less flammable it becomes.
However, the addition of OH to the carbon chain does widen the flammable range by a few percentage point on the lower and upper end.
Alcohols do not burn clear!
Methanol is a rare exception and it burns blue. That blue can be masked in the bright daylight
Those that vaporize to any degree the vapors can be irritating to our eyes and nose. Basically, it doesn’t play well with mucous membrane
Larger carbon structures tend to be less toxic than smaller ones
We know from experience ethanol is toxic. But we seem to have an affinity for it.
Some OH are nontoxic at all, like ethylene glycol
Wait doesn’t’ common wisdom say different
Metabolize it into toxic substance
OH in general so not enter thru the skin but you can get OH threw mucus membranes.
Eye shots, anal shots, tampons soaked with vodka
Ok it is important here to make a short note. While the alcohol functional group OH when attached to a carbon chain has relatively low toxicity the hydroxyl radical is a totally different story
This is the “OH” that would responsible for a lot of bases. So if you have an OH in the formula don’t just think it’s not toxic. It has to be connected to a carbon chain. Otherwise it can funk you up
Ya hydroxyl groups can cause bad tissue damage and genetic damage. Totally different that OH on a ethane molecule that will just get you arrested while you best friend is screaming that he told you she was a cop.
How do we find it
We mainly find it in the liquid form. Because of the Hydrogen bonding we are not likely to find them as a gas.
Even the smallest methanol has a BP of 137 degrees F
Many OH are steel or stainless steel containers
Drums, carboys
406, 407 and chemical carriers are common transportation vehicles
Where do find OH
They are used as fuels, disinfectants, solvents, and cleaners.
Are one of the most common functional groups
Nature uses it to almost as a linking mechanism.
Take fatty acids for example
The two chains containing OH are linked together when the OH is removed from the carboy group at the end of the chain.
What’s a carboxyl group…
That for another show.

The Hazmat Guys

Author: The Hazmat Guys


Please enter your comment!
Please enter your name here