Little_Ghost_again
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Chemical groups responsiable for scents in flowers
Hi
I am interested in finding out about the chemical groups that give flowers there smell.
I have looked at some esters etc but not sure thats the right direction.Can someone give me a direction to go sniffing in please 
Many thanks
LG
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Chemosynthesis
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Volatile esters are indeed some of the primary components of floral aromatic essential oils. "Volatile esters are common in floral scents, where they
may contribute substantially to the total scent output."
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC35117/
Also http://www.ncbi.nlm.nih.gov/m/pubmed/12692346/ and many more.
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Little_Ghost_again
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Hi
I found all kinds even vomit and death! Bubble gun etc etc. But what I am after or rather interested in is isolating different scents from certain
flowers, so i figured find the groups responsible and take it from there, if I know what groups I am looking for it narrows down what test's I need
etc.
I think its Butyric acid? thats the sick one, and putri something is death. I do have them written down but not handy so sorry for getting the names
wrong.
Most the ones I have looked at so far are just the same reaction but use different alcohols in the reaction like pentanol (sp).
I wondered if there were other groups I need to look at? Some I want to snyth, some I just want to isolate from there plant extract (if possible).
With this in mind does a rotavap make fractional distillation easier?
I ask because there is one available for around £250. I dont have the money yet but got some coming from some sales, also I have some glass ware to
put up in reagents section. But I dont want to buy one if its not going to add much help.
I didnt get any tomato plants despite asking in 8 gardening forums etc, so this spring I guess I am going to have to try and grow them again
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Oscilllator
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A rotavap does not make fractional distillation easier. The whole point of a rotavap is to strip off the solvent as quickly as possible, whereas in a
fractional distillation you want to precisely control the rate of evaporation so that the desired fraction comes over.
Rotavaps are really only useful if you are doing lots of extractions and don't have the patience to wait around for the solvent to boil off the normal
way. You are probably better off spending the £250 on something else, like a second hand hotplate/stirrer or a good distillation kit.
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Little_Ghost_again
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Quote: Originally posted by Oscilllator  | A rotavap does not make fractional distillation easier. The whole point of a rotavap is to strip off the solvent as quickly as possible, whereas in a
fractional distillation you want to precisely control the rate of evaporation so that the desired fraction comes over.
Rotavaps are really only useful if you are doing lots of extractions and don't have the patience to wait around for the solvent to boil off the normal
way. You are probably better off spending the £250 on something else, like a second hand hotplate/stirrer or a good distillation kit.
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Ok thanks for that, it will save me money , I have a hotplate stirrer but its
broke at the mo, I am waiting for a new rectifier for it.
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Etaoin Shrdlu
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Oh boy. You have esters, aldehydes, alcohols, ketones, and that's just the nice simple ones. Tiny changes between molecules often make an
astonishing difference, too. Are there any specific kind of flowers that you're interested in?
In my admittedly limited experience, alcohols tend to be subdued floral/soapy or green. Corresponding aldehydes have the same sort of undertone but
are brighter/sharper. The carboxylic acids take on rancid qualities (not always unpleasant) or lose their smell altogether. Esters often have
qualities of their corresponding alcohols/carboxylic acids, but not always. The rancid note from the acid goes away.
Diketones and alpha-hydroxy ketones are buttery. Pyrazines are earthy or green. Phenylacetic acid smells like honey; many of its derivatives do as
well. Nitriles are metallic citrus. All of the oximes I've smelled were either green or metallic or both but I know there are exceptions. Lactones
have a milky smell.
Ketones are astonishingly varied. They go from mild and earthy to mildewy to woody to sweet and fruity and that's without adding other
functional groups.
There are exceptions to everything I just said. 
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Chemosynthesis
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Ah. You may find a Soxhlet extractor or just steam distillation a good first step before fractional distillation, as this removes components from the
plant materials and is a great way to get essential oil extracts.
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diddi
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these guys have lots of glassware including essential oil distillation kits and Soxhlet extractors etc. they have free shipping after spend of about
$130.
a fractionating column would be a rather expensive creature I would expect, and as already stated, nothing like a rotavap.
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j_sum1
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Was there supposed to be a link in there diddi?
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diddi
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um..... yes
http://stores.ebay.com/nanshinglassware/
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j_sum1
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Looks identical to deschem http://stores.ebay.com.au/Deschem-Science-Supply/
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CuReUS
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for more information you could read the http://www.sciencemadness.org/library/ the 13th and 14th books by Ernest J. Parry.
chemosynthesis,i dont think buying a soxhlet extractor would be a good idea
i read somewhere that it was a watched equipment
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Little_Ghost_again
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Internet agro means I cant respond properly, but will try and read links.
Soxhlet is ok in UK, and have it covered 
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Little_Ghost_again
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I will come back once my internet is back to normal and explain exactly what I am after. Its not straightforward in some ways. I need analytical ways
to identify different smells if that makes sense.
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Little_Ghost_again
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Thanks for the links to the books, they are so good I am going to add them to my get in print list!
I have found some copies pretty cheap but no money at the mo as its all going on new equipment. Also unable to wash tractors for a while due to having
to avoid human contact as much as I can.
Really annoying as its prime cleaning time now!!!
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