Can Vinegar Turn into Methanol in Sunlight?

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SUMMARY

The discussion centers on the possibility of vinegar, specifically apple cider vinegar, converting into methanol when exposed to sunlight. Participants clarify that acetic acid (ethanoic acid) is produced through the oxidation of ethanol, while methanol (methanol) is not a direct product of vinegar under normal conditions. The presence of aluminum foil and saran wrap raises questions about potential photochemical reactions, but the consensus is that methanol production is unlikely. Concerns about the decomposition of saran wrap and the odors associated with methanol and hydrochloric acid (HCl) are also addressed.

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  • Understanding of organic chemistry, specifically oxidation reactions.
  • Familiarity with acetic acid (ethanoic acid) and its properties.
  • Knowledge of photochemical reactions and their implications.
  • Basic awareness of chemical odors and their identification.
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  • Research the oxidation of alcohols, focusing on ethanol and its derivatives.
  • Explore the photochemical properties of acetic acid and its reactions in sunlight.
  • Investigate the decomposition of polyvinylidene chloride (PVDC) in sunlight and its byproducts.
  • Learn about the chemical properties and safety concerns of methanol and its odor profile.
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Chemistry students, organic chemists, and individuals interested in the chemical properties of vinegar and its reactions under sunlight.

limitapproaches0
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is this possible?
see what i did was poured some apple cider vinegar into a cup and coverd it with saran wrap and overlapped so it would catch in my little aluminum foil base. i left it out in the sun for 2 days and when i approached it i may just be crazy but i could feintly smell the scent of methanol. i know methanol is used to make vinegar but is this possible. i didnt get too up close and personal with the cup b\c of fear it may have become methanol or some sort of aldehyde, so i just tossed it. so any chemists and this may be a tough one cause my mom wasnt sure and she is a chemist.
 
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Acetic or ethanoic acid is one of the simplest carboxylic acids (fatty acids). In the pure state it is a colourless liquid with an unpleasant pungent odour. It solidifies to an white or ice-like crystalline mass at 16.7°C (62.4°F), and hence is often called glacial ethanoic (acetic) acid. In a dilute form, mixed with water, it is the acid found in vinegar. Vinegar contains ~5%; or more ethanoic acid, produced by fermentation.

Ethanoic acid, known commonly as acetic acid (CH3COOH), is produced by the oxidation of ethanol. Ethanol is oxidized to acetaldehyde.

Methanoic acid, known commonly as formic acid (HCOOH), can be produced by oxidation of methanol (CH3OH). Methanol is oxidized to formaldehyde.

look at - OXIDATION OF ALCOHOLS
http://www.chemguide.co.uk/organicprops/alcohols/oxidation.html

Also - look at - OXIDATION OF ALDEHYDES AND KETONES
http://www.chemguide.co.uk/organicprops/carbonyls/oxidation.html

Also check this site for an overview of organic chem. I haven't scrutinized it, so I can't endorse it, but it may be useful.

http://www.mhhe.com/physsci/chemistry/carey5e/
 
so its unlikely i made methanol?
 
OK let's use some common sense here. Clearly this is not a thermal reaction since I have been cooking with various vinegars (including cider) for more years than I care to mention, and I have not gone blind. So this effect must be photochemical. Acetic acid does not absorb visible light, but cider vinegar is colored. Hence there is the potential for photochemical reactions with the chemicals that make it colored. What the exact composition of these chemicals are I have no idea so I can't speculate are to what the products would be. I would doubt methanol is a product since I've never seen a light sensitive warning on vinegars and many come in "clear" bottles.
 
but it was in the sun. and there was the presense of aluminum foil, in which aluminum is sometimes a catalyst in a chemical reaction.
 
OK I'm confused. You had the Al in the vinigar ?
 
no
the vinegar was in the cup and the cup was covered with saran wrap and the aluminum foil was placed under to collect any type of condensation that may have evolved
 
OK so how could the Al have any catalytic effect, outside of reflecting the light ?
 
im not sure. is it possible that i produced methanol?
 
  • #10
I doubt that aluminum foil would have had any catalytic effect, from what I remember the cationic form of aluminum does react with water in some sense...overall I doubt that you obtained methanol, how exactly are you familiar with the smell of methanol?
 
  • #11
not too familiar. i smelled it last year once in an octane booster. it has a really pungent methane like smell from what i remember. is it possible that other chemicals could have similar smell to it. anyways i really don't go around smelling chemicals.
 
  • #12
limitapproaches0 said:
not too familiar. i smelled it last year once in an octane booster. it has a really pungent methane like smell from what i remember. is it possible that other chemicals could have similar smell to it. anyways i really don't go around smelling chemicals.

HCl form decomposition of the saran wrap (PVDC) would be one possibility.
 
  • #13
Doesn't methanol smell slightly sweet? Or am I confused? I use it frequently to clean spectrophotometer lenses, BUT I have a very weak sense of smell so I often confuse things.

Regarding the saran wrap, does it decompose in sunlight? That would be somewhat worrying.
 
  • #14
rachmaninoff said:
Doesn't methanol smell slightly sweet? Or am I confused? I use it frequently to clean spectrophotometer lenses, BUT I have a very weak sense of smell so I often confuse things.

Regarding the saran wrap, does it decompose in sunlight? That would be somewhat worrying.

I agree with the comment about alcohols. I do not consider methanol, ethanol, or propanol to have a pungent odors. As for the saran wrap thought, HCl has a quite pungent odor. PCDV will photochemically decompose very very slowly (sorry I don't have a quantum yield for it), but the question would be can acetic acid accelerate it.