Traditionally the role of green notes in perfumery has been a minor one, but sine the 1960s their use has become increasingly more important in fragrance composition. Green notes are difficult to define and to have general agreement upon. The terms fatty, herbal, and green are often a source of contention. Green colours in nature are associated with vegetable matter that is healthy, living, growing, fresh, young. In perfumes or natural oils green notes are linked with naturalness, freshness, diffusion, and being "alive." In general, green notes are not major constituents of natural oils, but although they are often present in trace amounts, their odor impact is disproportionally great.
Aliphatic green notes
Aliphatic chemistry is rich in green notes, both naturally occurring and of synthetic origin. They are concentrated in the C5-C9 bracket. Looking at the aliphatic alcohols we see that n-heaxanol has a fatty somewhat fruity character yet in the introduction of an appropriate double bond give cis-3-hexen-l-ol which is call leaf alcohol, and possesses an intense green leafy, grassy note; very natural and "growing green" in character. The fatty note of the saturated alcohol has been almost totally eliminated.