Earliest output from a column - what is it?

[Alcophile]

Hi all,
I've noticed with my column (it's a CM still), having been under full reflux for a while, on marginally reducing the cooling, the 1st product (well before acetone) is a nasty smelling irritant, sulphurous smelling liquid.
Obviously this is discarded, just wondered if anyone knew what sort of compound it is?

[LWTCS]

Without being technical,,,straight up fores.

[Alcophile]

Yes, but clearly not esters or acetone, I was wondering what chemically

[Yummyrum]

Often folk get the smell of Acetone and ethyl acetate confused .Ethyl acetate is the major component of heads and there is a lot of it whereas Acetone is very concentrated in the fore-shots and there is little of it .

One things for sure, you can't smell Methanol as it had no smell .... iff’n thats what you’re worried about .

[still_stirrin]

The first smell I get off my reflux head is acetyaldehyde. It has that “green apple” smell. It is highly volatile and will usually boil off even as your boiler is coming up to a simmer. The amount of acetyaldehyde is minimal and it is usually gone before you start to produce any of the keytones, even before ethyl esters (ethyl acetate which has the fingernail polish remover smell) bubble up.

If you’re getting a sulfur smell, most likely a hydrogen sulfide smell, that is from reduction of the sulfurs in the ferment. Those constituents are not nearly as volatile, so I would believe it is not the first smells from your still. Also, H2S (rotten egg smell) is detectable at very low sensory thresholds, so a little bit has a big perception. Copper in the still will help reduce this too, so if your ferments tend to produce sulfur (often from high nitrogen or ammonia nutrients....or Turbo yeasts), make sure you have a lot of copper in your system.
ss

[LWTCS]

The first smell I get off my reflux head is acetyaldehyde. It has that “green apple” smell. It is highly volatile and will usually boil off even as your boiler is coming up to a simmer.

Yep. even before the lyne arm (or the like) gets hot.

[MartinCash]

+1 on acetaldehyde. Once you know the smell you'll pick it a mile away.

[Alcophile]

Pretty sure it's not acetaldehyde (methanal), not present any other time, not H2S either, and only very small volume of it. Not smelt any other time and not a smelly ferment (birdwatchers amongst others). Comes over even though still is in "full reflux with coolant water at about 16C.
Not really important what it is, merely curious!

[MartinCash]

I haven't done birdwatcher's, but I get acetaldehyde followed by acetone as the first thing out of my pot still, long before it's come to a boil, when doing sugar washes.

[still_stirrin]

And the fruit flies are telltale signs....they can smell the acetylaldehyde (green apple) from a mile away and come flying to your still house.

Acetone smells like paint thinner (solventy)...because it is. And ethyl acetate smells like fingernail polish remover (estery/fruity)...as it used to be used as such.
ss

[bilgriss]

+1 Still_Stirrin