Ketalization of 2‐heptanone to prolong its activity as mite repellant for the protection of honey bees

Abstract

BACKGROUND 2‐Heptanone is a volatile liquid known to be effective in protecting honey bees from parasitic mite infestations in hives. The present study aimed to show that chemical derivatives of 2‐heptanone would release the ketone for a significantly longer time than it takes for the pure ketone to evaporate and preferably for as long as two brood cycles of a honey bee (42 days). RESULTS A liquid ketal of 2‐heptanone with glycerol (Glyc‐Ket) and solid ketals of the ketone with polyvinyl alcohol (PVAl‐Ket), containing different amounts of the ketone, were synthesized. The fully resolved 1H and 13C nuclear magenetic resonance (NMR) spectra of the ketals are discussed. In the case of the polymer, differential scanning calorimetry (DSC) of a ketal was also compared with the unketalized polyvinyl alcohol. The length of time for which 2‐heptanone was released by the ketals was determined by gas chromatography‐mass spectrometry of the headspace. In the case of Glyc‐Ket, the concentration of the 2‐heptanone in the liquid phase was also monitored by 1H NMR spectroscopy. The deketalization was pH dependent, ranging between 2.0 and 2.5 for Glyc‐Ket and between 2.0 and 3.5 for PVAl‐Ket. CONCLUSION Under bee hive conditions, the release of 55 mmol 2‐heptanone from Glyc‐Ket lasted for 42 days, whereas the release of the ketone from the PVAl‐Ket with a similar amount of the ketone lasted for 23 days, versus a maximum of 17 days for an equivalent amount of the pure ketone. These ketals therefore have the potential to be effective mite repellants for the protection of honey bees. © 2019 Society of Chemical Industry

Optimization of the Pd-Catalyzed Alkylation of the Fermentation-Derived Oxygenates Acetone and Butanol toward Sustainable Aviation Fuel (SAF) Intermediates

“…The resulting alkane, n -heptane, is commonly used as a zero-point reference for engine testing (octane number of 0) being an undesired component in gasoline given its knocking fuel behavior, while it can be blended with diesel fuels as its cetane number of 56 falls in the range of suitable diesel fuel performance (cetane number of 51 or higher) . C7 itself can however also be used as a specialty chemical, most notably in the food and agricultural sectors as a food additive or pesticide . Considering this potential, it could be possible to either aim for those conditions where C7 is predominantly produced or aim to separate C7 from C11 for its further utilization as a side product.…”

“…38 C7 itself can however also be used as a specialty chemical, most notably in the food and agricultural sectors as a food additive 39 or pesticide. 40 Considering this potential, it could be possible to either aim for those conditions where C7 is predominantly produced or aim to separate C7 from C11 for its further utilization as a side product. However, if the aim is to increase the jet-fuel potential, given that C7 is the intermediate product for C11 formation, it is recommended to pursue its further alkylation either by optimization of the process conditions or by prolonging the reaction time until the formation of C11 is maximized.…”

Biosynthesis of 2-Heptanone, a Volatile Organic Compound with a Protective Role against Honey Bee Pathogens, by Hive Associated Bacteria

“…The lo concentrations of 2-heptanone produced by the bacterial strains investigated in this stud (<3 ng/mL), together with the high volatility of this compound, imply no side effects o the bees. Furthermore, in hives, its evaporation due to high temperature and humidi would be so quick that an investigation was specifically performed to maintain th compound longer to use it as a mite repellent [15]. The results of this study rather sugge that 2-heptanone may have a role in microbial chemical communication, and furth studies are needed for the exploitation of 2-heptanone-producing bacteria for the contr of honey bee pests and pathogens.…”

“…It has been recently discovered that honey bees use their mandibles to bite and remove Varroa mites from the bodies of their nest mates and that the released 2-heptanone acts as a local anesthetic, causing paralysis and death of this parasite [13]. The use of 2-heptanone as a mite repellent has been proposed, taking into consideration that this compound would not be toxic towards bees or contaminate hive products, since it already exists in hives [14,15].…”