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Wednesday, 30 July 2014

Lily of the Valley – mystery, manufacture & murder

Mystery

Perfumery has always glorified the floral and for centuries perfumers have sought ways to extract the essence from real flowers to incorporate into their creations. With many flowers this quest has met with considerable success, with a few commercially viable products produced that are still used in modern perfumery: rose and jasmine being the primary examples. 
Lily of the Valley - picture courtesy of Wikimedia Commons
One flower that has always eluded extraction is the Lily of the Valley (Convallaria majalis) or Muguet*: distillation yields very little of an unpleasant smelling oil not a bit like the dense, exotic scent of the fresh flowers.  Solvent extraction and even modern CO2 extracts have similarly been completely unable to capture the scent.  This is because the flower produces the scent only at the point of release – none is stored in the flower – so it cannot be extracted.  The flower itself only contains pre-cursor chemicals from which the scent is formed directly into the air.
Diorrissimo - picture from Basenotes
Yet many people will be familiar with the scent of Lily of the Valley, not through smelling the fresh flowers, but from perfumes containing or replicating its scent – perhaps the most famous of these being Diorissimo.  So, if you can’t extract the scent, how is that done?


*Muguet is the French word for Lily of the Valley, a flower popularly used at weddings.  Lily of the valley is a  sweetly scented (and highly poisonous) woodland flowering plant that is native throughout the cool temperate Northern Hemisphere in Asia, Europe and in the southern Appalachian Mountains in the United States.


Manufacture

Here we see how the chemist is the perfumers best friend: a good number of materials have been discovered or created that replicate, at least in part, the scent of these mysterious flowers.  Many people would say that synthetic Lily of the Valley begins with the synthesis in the early part of the 20th Century of Hydroxycitronellal: it’s difficult to be sure exactly when it was first used because the nature of the material was kept a closely guarded secret.  What we do know is that as early as 1906 it was being made by Givaudan and sold under the trade name Laurine. 
Dr E Emmet Reid
Credited with re-discovering Hydroxycitronellal
Image from The Johns Hopkins University
At the outbreak of WWI it was being manufactured in Germany and, as the war meant it ceased to be available, efforts were made to find ways to make it that resulted in it’s being manufactured in an American factory and, during the 20s, it gradually become well-known within the trade.  Most perfumers would agree that, while no one chemical can ever fully represent the scent of a flower, hydroxycitronellal gives a very close facsimile to the aroma of the fresh flowers of Lily of the Valley.  Curiously enough however it does not appear to be present in that, or any other natural flower scent.
I’m presenting in the sections at the end of this post, descriptions of a selection of materials that replicate the scent of Lilly of the Valley, with descriptions of their olfactory properties as well as, in many cases, the restrictions on their use that have led to their decline.  These are mainly for the benefit of DIY perfumers, but may also be of interest to perfumistas curious about ingredients.  I’ve included quite a few quotations from Steffen Arctander’s wonderful descriptions of aroma chemicals – rather less well known than his work on materials of natural origin – but just as good.


Murder

Structure of Lyral - image courtesy Wikimedia Commons
So where does the murder come in?  Well in one case a forthcoming ban by the European Union will, over the next couple of years, result in the certain demise from perfumery altogether of one of those materials.  The material that is being killed off by the regulators is Lyral and although it’s only going to be banned in the EU, that will very likely be reflected in a prohibition by IFRA (the International Fragrance Association) and even if it isn’t all the major perfume manufacturers will phase it out of use completely, so it will effectively vanish from the world.

After the jump you can read detailed descriptions of a range of materials used in connection with Lily of the Valley scents.

The Technical Stuff

The descriptions that follow are in alphabetical order by the name most commonly used for the material.  This isn’t a complete list of everything ever used for Muguet fragances, but it does cover all the common materials with a clear muguet note as well as one or two of the main modifiers.  Where applicable I’ve mentioned the IFRA limitation for alcoholic fine fragrances (not including aftershaves).

I’m indebted to many sources besides my own experience for this material, but primarily the already credited Arctander, the major manufacturers of the materials concerned and The Good Scents Company who maintain an excellent online database of perfumery materials, plus of course Wikimedia for the remaining images. 

Bourgeonal

CAS Number: 18127-01-0

Full chemical name:

3-(4-tert-butylphenyl)propanal

Very powerful and once widely used, this is one of the earliest Lily of the Valley chemicals.  This description is from Givaudan: “Odor: Floral, Green, Muguet, Fresh, Powerful.  Use: Bourgeonal is a powerful, diffusive fresh floral muguet, with a watery green character. Its unique muguet-aldehyde character is extensively used in toiletries and alcoholic fragrances.

Today its use is limited by IFRA to 0.5% of the product


Cyclamen Aldehyde

CAS Number: 103-95-7

Full chemical name:

3-(4-propan-2-ylphenyl)butanal

Powerful and versatile, the odour is described as: floral cyclamen, fresh, rhubarb, musty and green. Unlike many aldehydes it is stable in most media and its substantivity makes it very useful.  Not quite as strong as some aldehydes it is still most often used in dilution.

Arctander describes it as “Diffusive and powerful floral-green, floral-stem like odor with pronounced vegetable Cucumber-Melon-like notes. Overall resembling the odor of Lindenblossom.
Extensively used in perfumery for floral effects, fresh-green-floral topnotes (of lasting fragrance), Useful in Lilac, Lily, Peony, Magnolia, Orangeblossom, Alpine Violet, etc.
Blends well with the Ionones and all Rose notes.


Dupical

CAS Number: 30168-23-1

Full chemical name:

4-(octahydro-4,7-methano-5H-inden-5-ylidene)butanal

A Givaudan product described by them as “Odor: Floral, Green, Muguet, Fresh.  Use: Dupical is a powerful, fresh, transparent aldehydic muguet. It is a wonderful modifier and enhancer of the muguet character in a fragrance. Thanks to its powerful performance, it can be used in all applications.  Typical aldehydic strength restricts the amount of this material that appears in fragrances to 3% or (usually much less) of the concentrate.


Farnesol

CAS Number: 4602-84-0

Full chemical name:

3,7,11-trimethyldodeca-2,6,10-trien-1-ol

The odour is described as a delicate, fresh, green muguet note; mild, sweet, linden-floral and angelica but also as having fruity and spicy aspects such as anise; apricot; balsam; clove; grapefruit; oily; orange; peach; pear. 

Farnesol is one of the classic perfumery ingredients and is present in many flowers and herbs from neroli to wild thyme. Once reserved only for the most expensive fragrances it became more widely available at the end of the 1960s when synthesis methods improved.

Recommended usage levels are from traces to 1.2% of the finished product (the IFRA limit for alcoholic fragrances). Tenacity is impressive at around 16 days on a smelling strip meaning it is a base note, but it has middle-note effects as well. It is stable in soaps and lotions.

Arctander recommends it as “an excellent background note and blender in the delicate floral such as Muguet, Lilac, etc. or in the balsamic types, Oriental fragrances, Chypres etc. It combines the softest woody notes of Orris with the sweet and balsamic floral notes of Muguet, Rose, Magnolia, Acacia, etc. It blends excellently with Ylang Ylang, Cassie, Rose, Violet, Neroli, Cyclamen, etc. and it is an almost necessary ingredient in the so-called ‘Linden- blossom’ type fragrance.

Limited by IFRA to 1.2% of the finished fragrance.


Floralozone

CAS Number: 67634-15-5

Full chemical name:

 3-(4-ethylphenyl)-2,2-dimethylpropanal

Also called Ozone Propanal and Florazon this is a powerful material, made by IFF (International Flavors and Fragrances), and is described by them like this “Powerful, clean, green, fresh air note reminiscent of ocean breezes. Gives lift to fragrances without dominating due to its neutral nature“
Floralozone can be used to give a subtle, fresh lift to almost any fragrance when used in small amounts but it is especially useful in floral (especially Muguet) compositions – use too much and the fragrance may become too ozonic however.   Used in moderation it is ideal for adding a ‘fresh-air’ note to fragrances.


Florhydral

CAS Number: 125109-85-5

Full chemical name:

 3-(3-propan-2-ylphenyl)butanal

Also called Floral Butanal this is a powerful material, made by Givaudan, and is described by them like this “Floral, Green, Muguet, Fresh, Powerful. Florhydral has a very floral, fresh, trendy, natural odour (such as lily-of-the-valley, hyacinth...). Its great intensity and pleasant quality make it useful in all areas of perfumery. Florhydral is also valuable in fragrances for laundry products where a fresh residual odour is desired. Florhydral gives naturalness together with aldehydes in citrus accords."
A superb freshening agent in any floral context, it exalts citrus very well and of course is ideal where you need a Lilly of the Valley note that isn’t restricted by IFRA. 

Best used sparingly except in Lilly of the Valley applications.  Recommended usage is 0.2-2% and tenacity is a week on a smelling strip, this material also works well in burning applications such as candles and joss sticks.


Helional

CAS Number: 1205-17-0

Full chemical name:

 3-(1,3-benzodioxol-5-yl)-2-methylpropanal

Also called ocean propanal this product was developed by IFF, who describe it like this: “Green, floral (cyclemen) with top notes of ozone and new mown hay.” I’m not sure they are doing it justice – this is a lovely ingredient with a wonderfully fresh, watery quality.

Helional is very easy to use, providing a fresh, light quality.  It blends well with other green notes and is one of very few such notes that can be used fairly freely – unlike many green fragrance materials it isn’t so strong that you have to use it with caution to avoid overdoing it.

Limited by IFRA to 5.3% of the finished fragrance, but that’s plenty to have a good impact.


Hydroxycitronellal

CAS Number: 107-75-5

Full chemical name:

7-hydroxy-3,7-dimethyloctanal

One of the best of the range of synthetics used to recreate the scent of the Lily of the Valley (muguet).  Like most of the other materials that imitate that flower it is an aldehyde.  Hydroxycitronellal is widely regarded as the single most accurate representation of the Lily of the Valley flower used in fine fragrance and other areas and combines well with other floral and green materials.  The scent is described as having sweet-floral perfume-like notes with green citrus and melon undertones.
Vintage versions of fragrances such as Diorrisimo used large amounts of this material, but today its use is limited by IFRA to 1% of the product.


Hydroxycitronellol

CAS Number: 107-74-4

Full chemical name: 

3,7-dimethyloctane-1,7-diol

Odour type is floral with a low odour strength has a mild, clean, floral note and is very long lasting and closer to rose than muguet, with aspects of lily and peony. 

Excellent fixative and essential stabiliser for the better-known aldehyde (hydroxycitronellal).

Arctander gives more information:
“Very mild (weak) clean-sweet, floral odour of considerable tenacity. The floral type is Rose-Peony, typically less green, less Lily or Muguet than the aldehyde.  He goes on to tell us that this alcohol, now often manufactured as an intermediate in the production of Hydroxycitronellal, is used in perfume compositions originally with the intention of stabilizing Hydroxycitronellal and prolonging the odour life of that aldehyde in composition.
However, there are other uses for this alcohol, not always obvious from a brief glimpse at the odour, which is, truly, not immediately impressive. It has an excellent fixative effect upon many types of delicate floral fragrance, and as a blender/modifier for other types.
The use of Hydroxycitronellol as a stabilizer for Hydroxycitronellal is still practised, but the author finds that the alcohol has much wider possibilities and virtues of its own as an odorant.


Lilial

CAS Number: 80-54-6

Full chemical name:

 3-(4-tert-butylphenyl)butanal

One of a range of synthetics used to recreate the scent of the Lily of the Valley (muguet).  Like most of the other materials that imitate that flower it is an aldehyde.  Lilial is widely used in fine fragrance and other areas and combines well with other floral and green materials.  The scent is described as floral muguet, watery, green, powdery and cumin.

Its use is limited by IFRA to 1.9% of the product.


Lyral

CAS Number: 31906-04-4

Full chemical name:

 4-(4-hydroxy-4-methylpentyl)cyclohex-3-ene-1-carbaldehyde

More Convallaria majalis, here with a suitably blood-red
background for the soon-to-be-murdered Lyral!
Synonyms include: cyclohexal, kovanol, leeral, mugonal, HICC, HMPCC

One of a range of synthetics used to recreate the scent of the Lily of the Valley (muguet).  Like most of the other materials that imitate that flower it is an aldehyde.  Lilial is widely used in fine fragrance and other areas and combines well with other floral and green materials.  The scent is described as floral muguet, watery, green, powdery and cumin.

Its use is already limited by IFRA to 0.2% of the product and it is about to be banned altogether by the EU, which will almost certainly result in it vanishing from perfumer’s palettes worldwide.


Melafleur

CAS Number: 68991-97-9

Full chemical name:

8,8-dimethyl-2,3,4,5,6,7-hexahydro-1H-naphthalene-2-carbaldehyde

Synonyms include: cyclemone A; cyclomugual; muguet carboxaldehyde

Odour type is floral, with a medium odour strength: floral, clean, muguet, ozone, marine, sandy and balsamic.

Manufactured by IFF who say this of it: “A substantive floral muguet product having the odour of fresh outdoors with a green, melony background.”

Useful in a wide range of fragrances to give a fresh lift as well as extremely helpful when you’re trying to create a good Muguet and have run up against the IFRA limits on the more widely used materials in this category as Melafleur has no restriction and can form up to 15% of your concentrate if you wish.


Mugetanol

CAS Number:  63767-86-2

Full chemical name:

1-(4-propan-2-ylcyclohexyl)ethanol

Synonym: Muguet ethanol

Produced by Symrise, this is another unrestricted alternative to the older Lily of the Valley ingredients, described by them thus: “Odor: light floral, reminiscent of muguet, with waxy elements

Particularly useful because, being an alcohol, it is more stable than many of the others and has no IFRA restrictions.


Precyclemone B

CAS Number:  52474-60-9

Full chemical name:

1-methyl-3-(4-methylpent-3-enyl)cyclohex-3-ene-1-carbaldehyde

Also called myrmac aldehyde this material is manufactured by IFF, who describe it like this: “Clean, tenacious, ozone note with aldehydic warmth and diffusion. Booster for fragrances requiring a fresh outdoors effect.”

Best used in small amounts, this is a really excellent fresh-air ingredient. With Precyclemone B you get a very long-lasting freshening effect that works exceptionally well in citrus fragrances where you want to prolong the fresh feel beyond the life of the short-lived citrus oils.  In traces it can lighten almost any perfume, larger amounts can be used in room-fresheners and marine compositions.


Silvial

CAS Number: 6658-48-6

Full chemical name: 

2-methyl-3-[4-(2-methylpropyl)phenyl]propanal

Synonym: cyclamen homoaldehyde

Floral, green, aldehydic and marine this is a powerful and very persistent ingredient manufactured by Givaudan.  It is ideal for use in Lily of the Valley fragrances and works well with other muguet ingredients.

Givaudan describe it like this: “Silvial is a powerful, vibrant muguet ingredient with a slight citrus undertone and a fresh, aldehydic touch that is used in perfumery in the same way as related muguet products

It is restricted by IFRA to 1.04% of the finished alcoholic fragrance (in aftershaves the amount is only 0.55%) though that’s plenty to give impact as this material is so powerful.


Undecavertol

CAS Number: 81782-77-6

Full chemical name:

 (E)-4-methyldec-3-en-5-ol

An unusual material, also known as Violet Decenol, this is a brilliant ingredient for many floral blends that helps to bring out the floral and fruity aspects of other materials. 

Description from Givaudan: "Undecavertol was developed in connection with structural elucidation work on unknown trace components of lily-of-the-valley. It has a powerful green-floral character, somewhat related to lily-of-the-valley, with natural, fresh, fruity violet leaf and linden-blossom aspects. It can be used successfully in rose and fruity pear accords. Although easy to use in most perfumery types, Undecavertol requires careful dosage and blending due to its exceptional strength."