Newsgroups: sci.chem
Subject: Re: Esters (the nose knows)
Summary: Characteristics and preparation of esters
Keywords: esters, fruits, fragrances
Date: 7 Apr 91 15:24:54 GMT

In article <1991Apr6.083246.6642@ms.uky.edu> ghot@ms.uky.edu (Allan
Adler) writes:

>Larry Lippman was kind enough to post a list of esters and fruits where they
>occur.

	You must bear in mind that my list was but a small fraction of esters
which have been identified in fruits.

>(1) Although these esters occur in fruits, are they toxic and if so what
>    do they do to you in sufficient doses ?

	Many esters have toxic effects resulting from exposure to significant
concentrations; however, in comparison to many other organic compounds,
esters are rather benign.

	A good example is amyl acetate, the mixed isomers of which are
commonly called "banana oil".  Amyl acetate smells decidedly like bananas,
and in *very* dilute concentration tastes like bananas.  Pure amyl acetate
is a not only a rather good solvent, but is highly flammable.  If you
tasted *pure* amyl acetate, I can assure you that you would not taste
anything else for quite some hours, although the experience would probably
result in no permanent injury.  Breathing significant concentrations of
amyl acetate can result in headache, nausea, irritation to mucous membranes,
and possibly unconsciousness.  Amyl acetate in high concentrations has a
narcotic effect.

	Comparatively few esters used in fragrances and flavoring are
suspected carcinogens.  However, any such carcinogenicity no doubt results
from prolonged exposure to significant concentrations.  Since many esters
are used as industrial solvents, such exposure can occur.  As an example,
offhand, I believe that ethyl formate is a suspected carcinogen.  Chronic
exposure to ethyl acetate from use as an industrial solvent can result in
secondary anemia, fatty degeneration of the liver, leucocytosis, etc., but
I do not believe it is a suspected carcinogen, per se.  Nevertheless, ethyl
acetate in minute quantities is used in the formulation of flavorings and
fragrances.

>(2) How hard are they to synthesize if, like me, you do not know your 
>    gluteus maximum from your olekranon ?

	Esters are comparatively easy to synthesize when such synthesis
is performed in a laboratory environment with suitable apparatus and
suitable analytical instrumentation to evaluate the product and efforts
at purification.  Proper synthesis also requires "finesse", which is solely
the product of experience in a laboratory.

	I suspect your real question is: can esters be synthesized in
a home laboratory environment?  The simple answer is probably "yes"
if one has previous organic synthesis experience and some kind of
suitable glassware.  If one is attempting such a synthesis for the
first time on their own at home, then anything is possible - ranging
from success to utter disaster.

>(3) How hard is it to extract them from a piece of fruit, given the same
>    limitations on competence as in (2), and what yields can one expect ?

	This is really the same answer as in the previous question, but
I suspect that extraction and separation is probably easier for certain
esters than synthesis.

	If you are going to try something at home, I would first recommend
an effort at extraction.  You can probably build a simple filter press
using an inexpensive hydraulic auto jack with a metal frame and a simple
housing for the filter pads.  It is neither difficult nor particularly
expensive to acquire the apparatus necessary for fractional distillation.
The challenge, however, is to scrounge apparatus necessary for analysis
of the products; after all, what is the point of synthesizing or extracting
esters if you cannot be certain of their identification?  Such analytical
apparatus is not inexpensive, even in the used equipment marketplace.  If
I had to recommend one single piece of analytical apparatus that could be
the most useful for the analysis and identification of esters  - and yet
still be affordable and maintainable, it would be an Abbe refractometer.

	While an IR spectrophotometer would be nice, there are generally
only two types of IR spec's to be found as used apparatus: (1) functional
and (2) inexpensive.  Unfortunately, there is little hope of finding a used
IR spec that is *both* functional and inexpensive. :-)  Inexpensive used
IR specs often have defective detectors and/or deteriorated salt optics,
the cost to repair being prohibitive for either condition.

>(4) Since I am always on the lookout for interesting crystals, what kinds
>    crystals do they form, how large can they be grown by someone with
>    the competence described in (2), and where would one look up their
>    principle dielectric constants (I am assuming they are biaxial) ?

	Most of the esters used in flavorings and fragrances are liquids,
so you won't find much in the way of crystals.  Those esters which are
solids tend to have low melting points.  An example is benzyl cinnamate,
which has a melting point of less than 40 deg C.
	
>(5) Do all crystals from substances like these tend to sublime ? Naively
>    I would expect that since I would guess that goes with having a strong
>    smell. If so, how long does it take for the crystal to disappear in a
>    hood ?

	In the case of the above example of benzyl cinnamate, the crystals
clearly fuse and melt, and I would not consider this as "sublimation".  The
same characteristic is true of cinnamyl cinnamate, methyl anthranilate and
methyl cinnamate.  Some of these melting points are around 30 deg C.

>(6) I tend to think of fruit juices as sticky ? Are the crystals sticky ?

	I would not consider the comparatively few solid esters as
"sticky".  Don't forget that the presence of sugars no doubt accounts
for any "stickiness" in evaporating fruit juices!

>Someday when I have an education, I will ask better questions. Right now,
>this is the best I can do.

	You do allright.  You seem to sincerely want to learn about
chemistry  - more so than anyone I have yet encountered on the Net.

Larry Lippman @ Recognition Research Corp.  "Have you hugged your cat today?"
VOICE: 716/688-1231       {boulder, rutgers, watmath}!ub!kitty!larry
FAX:   716/741-9635   [note: ub=acsu.buffalo.edu] uunet!/      \aerion!larry

From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: sci.chem
Subject: Re: Esters (the nose knows)
Summary: Reference data sources & coriander constituents
Keywords: esters, fruits, fragrances
Message-ID: <4870@kitty.UUCP>
Date: 12 Apr 91 04:35:52 GMT

In article <5380@eastapps.East.Sun.COM> gsteckel@east.sun.com (Geoff
Steckel - Sun BOS Hardware CONTRACTOR) writes:

>Where would I look for references on the composition of flavors or essences?
>The Merck manual has a tantalizing glimpse of this fascinating subject, but
>it only mentions flavorings in passing.  Is there a Journal of Savory Smells,
>Archives of Abstracts of Essences, or equivalent?
 
	For contemporary textbooks you might consider: "Source Book of
Flavors", "Flavor Chemistry and Technology", "Common Flavor and Fragrance
Materials", etc.  There are also various older textbooks which contain a
wealth of information. 
 
	For periodicals you might consider: "Perfumer & Flavorist", "Flavour
& Fragrance Journal", "Flavouring Ingredients Processing & Packaging", etc.
 
	In addition, various manufacturers of flavors and fragrances, such
as Norda, publish application literature giving details about composition
of flavors and fragrances.
 
>Does anyone know what the heck the extremely volatile odor/flavor components
>of coriander leaves are?  Not the seeds, which have a different flavor.
 
	Coriander contains d-linalool (3,7-dimethyl-1,6-octadien-3-ol)
and d-pinene.  These constituents are found in coriander *fruit*; I cannot
speak with certainty about the seeds.  Linalool is also found in oranges,
cinnamon, sassafras and other plants.  Pinene is also the major constituent
of turpentine (blech!).
 
>I'd settle for a reliable extraction procedure so I could extract 10Kg of
>cilantro in late summer when it's available, strong, and cheap....
 
	I would guess that steam distillation of coriander fruit is used
to obtain coriander oil.  You could probably use a filter press, which
would be easier to construct, although it would not be as efficient as
direct steam distillation.  The oil resulting from filter pressing could
then be refined with conventional fractional distillation. 
 
Larry Lippman @ Recognition Research Corp.  "Have you hugged your cat today?"
VOICE: 716/688-1231       {boulder, rutgers, watmath}!ub!kitty!larry
FAX:   716/741-9635   [note: ub=acsu.buffalo.edu] uunet!/      \aerion!larry

From: larry@kitty.UUCP (Larry Lippman)
Subject: Re: Esters (the nose knows)
Summary: IUPAC names
Date: 13 Apr 91 17:26:40 GMT
Organization: Recognition Research Corp., Clarence, NY

In article <1991Apr12.232122.16768@ucselx.sdsu.edu> naqvi@ucselx.sdsu.edu
(Shahid A. Naqvi --Hercules--) writes:

>Can somebody provide the IUPAC nomenclature for these esters. I know
>ethyl acetate is ethyl ethanoate [pear drops fragrance] but I am clueless
>about most of the ones listed. Come on guys, we don't live in medieval
>times anymore!! We are almost in the 21st century!

        IUPAC is a great idea - if we could suddenly wake up one morning
and magically find that all present and past chemical literature has been
translated to IUPAC nomenclature, in addition to having our collective
chemical education so translated.

        IUPAC is only very slowly being adopted by chemical industry and
commerce in the U.S.  I would gladly attempt to learn and utilize more
IUPAC if only the people I deal with knew what I would be referring to!

>[Don't you think that the IUPAC was introduced to make life less miserable!]

        There are times when I have my doubts. :-)

        Okay, here's your "translation".  I will not stake my life upon
the correctness of all translations, especially the cycloalkyls.
        
|>allyl caproate        2-propen-1-yl hexanoate
|>amyl acetate          pentyl ethanoate
|>amyl butyrate         pentyl butanoate        
|>amyl caproate         pentyl hexanoate
|>amyl valerate         pentyl pentanoate
|>benzyl acetate        benzyl ethanoate
|>bornyl acetate        1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol ethanoate
|>iso-butyl acetate     2-methylpropyl ethanoate
|>ethyl acetate         ethyl ethanoate
|>ethyl butyrate        ethyl butanoate
|>ethyl caproate        ethyl hexanoate
|>ethyl cinnamate       ethyl 3-phenyl-2-propenoate
|>ethyl formate         ethyl methanoate
|>ethyl isovalerate     ethyl 3-methylbutanoate
|>ethyl heptanoate      ethyl heptanoate        [How 'bout dat! :-) ]
|>ethyl lactate         ethyl 2-hydroxypropanoate
|>ethyl pelargonate     ethyl nonanoate
|>geranyl acetate       3,7-dimethyl-2,6-octadien-3-yl ethanoate
|>geranyl butyrate      3,7-dimethyl-2,6-octadien-3-yl butanoate
|>geranyl valerate      3,7-dimethyl-2,6-octadien-3-yl pentanoate
|>linalyl acetate       3,7-dimethyl-1,6-octadien-3-yl ethanoate
|>linalyl butyrate      3,7-dimethyl-1,6-octadien-3-yl butanoate
|>linalyl formate       3,7-dimethyl-1,6-octadien-3-yl methanoate
|>menthyl acetate       5-methyl-2-(1-methylethyl)cyclohexanol ethanoate
|>methyl benzyl acetate         methylbenzene ethanoate
|>methyl cinnamate      methyl 3-phenyl-2-propenoate
|>methyl phenyl acetate         methylphenyl ethanoate
|>methyl salicylate     methyl 2-hydroxybenzoate
|>methyl anthranilate   methyl 2-aminobenzoate
|>nonyl caprylate       nonyl octanoate
|>octyl butyrate        octyl butanoate
|>terpenyl butyrate     1,7,7-trimethylbicyclo[2.2.1]hept-2-yl ethanoate

        After doing the above list, I now have a headache.  I know there
are some white pills that I should take for it, but I can't recall their
IUPAC name... :-)

Larry Lippman @ Recognition Research Corp.  "Have you hugged your cat today?"
VOICE: 716/688-1231       {boulder, rutgers, watmath}!ub!kitty!larry
FAX:   716/741-9635   [note: ub=acsu.buffalo.edu] uunet!/      \aerion!larry