Fatty Acetates

Introduction

Fatty acetates belong to the family of lipids that are abundant in nature and they are classified as short-chain and long-chain acetates. Among them, many insect pheromones contain long-chain fatty acetate components. For instance, acetates can be extracted from the glands of the spruce budworm moth in relatively high abundance, which has been explained by labeling experiments. It is noteworthy that fatty acetates are the most abundant type of pheromones secreted by Lepidoptera.

Moreover, there are multiple methods to synthesize fatty acetates, including direct synthesis via fatty alcohols. The direct synthesis of acetates by fatty alcohols has been confirmed by studies on insect pheromones. Research has found that fatty alcohols secreted by some insects are the main components of pheromones, but there are also large amounts of acetates in the pheromone-producing glands ^[1].

Fig. 1 Common molecular formula and acetate units for fatty acetates.

Octyl acetate is a saturated fatty acetate with the formula C₁₀H₂₀O₂ that appears as a colorless liquid and smells fruity like orange and jasmine. It occurs naturally in plant or insect secretions and can also be artificially synthesized by the esterification of 1-octanol and acetic acid.

Fig. 2 The chemical structure of octyl acetate.

As an aliphatic ester, octyl acetate is the main constituent of the essential oil in the vittae, or oil tubes, of the wild parsnip (Pastinaca sativa). By analyzing these octyl acetate esters in wild parsnip fruits from 30 maternal families, the mean content of octyl acetate was calculated as 1.56 microg/mg dry fruit, as shown in Fig. 3. Besides, the narrow-sense heritability of octyl acetate content was calculated by half-sib family analysis (HS) and parent-offspring regression (OP), which showed heritabilities of 0.389 (HS) and 0.654 (OP).

Moreover, octyl acetate also exists in the secretion of insects, which has the function of defense and warning. It can also be used as a solubility agent to carry toxins. For example, aliphatic octyl acetate serves as a minor component of its formic acid spray in the carabid Helluomorphoides clairvillei (Coleoptera) ^[2].

Fig. 3 Chemical content (μg/ml dry fruit) of octyl acetate ^[2].

Tridecyl acetate is a saturated fatty acetate. The molecular formula is C₁₅H₃₀O₂ and the molecular weight is 242.40.

Fig. 4 The chemical structure of tridecyl acetate.

Tridecyl acetate and its derivatives are mostly the main components of sex pheromones. For example, its derivative 3,7,9-trimethyl-2-tridecyl acetate is the main component of the sex pheromone secreted by female insects of Macrodiprion nemoralis. The precursor of this sex pheromone is a threo-3,7, 9-trimethyl-2-tridecanol isomer with four stereocenters, and a mixture of 3,7,9-trimethyl-2-tridecyl acetate isomers synthesized from this alcohol has been reported to be able to capture the Macrodiprion nemoralis well. Therefore, the mixture of tridecyl acetate isomers must contain the active ingredient of pheromones. After separation and purification by gas chromatography-mass spectrometry, the pheromone active ingredient is finally identified as (2S,3R,7R,9S)-3,7,9-trimethyl-2-tridecyl acetate (SRRS-5A) ^[3].

Alfa Chemistry has a wide range of fatty acid esters for customers to choose from. If the products you look for are not in our catalog, please don't hesitate to contact us and we would be pleased to offer you more details.

References

1. Kaewkool, P.; Krisnangkura, K. Transesterification/acetylation of long chain alcohols with alkyl acetate. Chemistry and Physics of Lipids. 2010, 163: 685–688.
2. Carroll, M. J.; Zangerl, A. R.; Berenbaum, M. R. Heritability estimates for octyl acetate and octyl butyrate in the mature fruit of the wild parsnip. J Hered. 2000, 91(1): 68-71.
3. Wassgren, A. B.; et al. Sex pheromone of the pine sawfly Macrodiprion nemoralis (Hymenoptera:Diprionidae): identification of (2S,3R,7R,9S)-3,7, 9-trimethyl-2-tridecanol as the precursor for the active pheromone acetate. Die Naturwissenschaften. 2000, 87: 24-9.