GREEN, GREEN GRASS: LEAF ALCOHOL

Welcome to materials Wednesday as the green lineup continues. 

Most people seem to love the smell of freshly cut grass. I don’t – in fact I find the smell of freshly cut lawn grass slightly disgusting. Maybe it’s because I associate it with the nasty clumps of green slime that I have to remove from the weedeater after I’ve been cutting the jungle of tall grass and other plants that takes over our little farm every summer right at the end of the rainy season, or maybe it’s just because I don’t associate that smell with childhood suburban lawns the way many people in the US do.

Cis-3-hexenol, aka leaf alcohol, is one of the main odorants that occurs naturally in grass, leaves, and other green plants. It’s used in artificial flavorings for food like “watermelon” and “green apple”. By itself, it does a perfectly convincing imitation of “cut green grass”, and is probably the main (or only) fragrance ingredient in those commercial fragrance oils called “fresh-cut grass”, “bamboo”, and the like. If you like the smell of macerated green vegetation, this one’s definitely for you.

As you can tell, I’m not fond of this material, and have used it only in trace amounts in creating green scents of various types. It serves as a powerful top note, but given that it only lasts a few hours neat on paper, it needs other materials to extend longevity and temper the super-grassy smell.

Leaf alcohol is one of the “green leaf volatiles” that is released from wounded leaves when insects like caterpillars feed on them. In some cases the leaf alcohol that’s floating around attracts more pests, but more often than not it repels them, or even attracts the enemies of the pests, which is what the plant wants. There is also some evidence that the most important role of leaf alcohol is to provide a means of communication among plants, triggering preemptive defense mechanisms in intact plants if their neighbor has been attacked. You can read all about it here.

It never ceases to amaze me that the chemical defense mechanisms of plants have produced so many wonderful perfume materials that we, as humans, enjoy. If you want green scents, leaf alcohol is a must-have to achieve that grassy green scent note. Just watch out for that very hungry caterpillar! Or maybe if you wear it while gardening, it will boost the defense mechanisms of your favorite plants.

[All images are from Wikimedia]