1-Hexadecene and Its Applications

1-Hexadecene, a long-chain alpha-olefin (LAO)containing 16 carbon atoms, commonly used as a precursor in the production of synthetic detergents, plasticizers, and various chemicals for the chemical industry. Additionally, it is a key component in commercial LAO blends, contributing to the manufacturing of tanning oils, synthetic fatty acids, and drilling fluids. A study evaluated newly synthesized copolymers and their montmorillonite nanocomposites as cold flow improvers for petroleum lubricating oils, including formulations with 1-Hexadecene, demonstrating enhanced flow properties.

Antimicrobial and Antioxidant Activities and Effect of 1-Hexadecene

Spirobisnaphthalenes (also namely bisnaphthospiroketals) are a growing group of fungal metabolites which contain two 1,8-dihydroxynaphthalene-derived units bridged through a spiroketal linkage. They are divided into four subclasses, namely spiroxin-, preussomerin-, deoxypressomerin- and urnucratin-type spirobisnaphthalenes, according to their structural features. In our previous studies, a variety of bioactive deoxypressomerin-type spirobisnaphthalenes were isolated from the endophytic fungus Berkleasmium sp. Dzf12 derived from a medicinal plant Dioscorea zingiberensis. Berkleasmium sp. Dzf12 was also found to be a high producer of palmarumycins C12 and C13. As part of our ongoing program to search for other palmarumycins from Berkleasmium sp. Dzf12, both palmarumycins C2 and C3 were found to be the main spirobisnaphthalenes produced after addition of 1-hexadecene to the culture medium. In this report, we describe the isolation and structural elucidation of palmarumycins C2 and C3 along with their antimicrobial and antioxidant activities. The enhancing effects of 1-hexadecene on production of palmarumycins C2 and C3 in liquid culture of endophytic fungus Berkleasmium sp.Dzf12 were also studied.[1]

In this work, two spirobisnaphthalenes (palmarumycins C2 and C3) were first isolated from the liquid cultures of endophytic fungus Berkleasmium sp. These compounds should be further studied. After addition of 1-hexadecene to the medium at 10% on day 6 of culture, the maximal yields of palmarumycins C2 and C3 were obtained (0.40 g/L and 1.19 g/L), which were 40.00 fold and 59.50 fold higher in comparison with those of the control (0.01 g/L and 0.02 g/L, respectively). Addition of 1-hexadecene in liquid culture of endophytic fungus Berkleasmium sp. Dzf12 could be an efficient method to produce palmarumycins C2 and C3. Some alkanes (i.e., n-hexane, n-dodecane and n-hexadecane) were previously reported to increase metabolite production by acting as oxygen-vectors. Typical examples included lycopene and β-carotene production, enhanced by both n-hexane and n-dodecane in Blakeslea trispora, lovastatin production enhanced by n-dodecane in Aspergillus terreus, and arachidonic acid production enhanced by n-hexadecane. To our knowledge, this is the first report on the metabolite production enhanced by it in microbial culture. 1-Hexadecene, belonging to the alkenes, probably either acts as the oxygen-vector or plays a role in the redox system to increase palmarumycin C2 and C3 production in Berkleasmium sp. Dzf12, which needs further investigation. Palmarumycins C2 and C3 were considered as the intermediates in the biosynthetic pathway of spirobisnaphthalenes. It should be beneficial for us to further study the biosynthesis of spirobisnaphthalenes.

Enhancement of methane production from 1-hexadecene

Linear alpha olefins (LAO) are obtained from crude oil refinery and consist of unsaturated straight‐chain hydrocarbons containing a double bond at the primary or alpha position (American Chemistry Council, 2006). Global LAO consumption has increased at an average annual rate of 5.6% from 2012 to 2016 and is expected to continue at 3.7% average annual rate until 2021 (IHS Markit, 2017). 1-Hexadecene, a LAO with 16 carbon atoms, is abundant (i.e. 60–68%, Chevron Phillips Chemical Company, 2013) in LAO commercial blends that are used in the production of tanning oils, synthetic fatty acids and drilling fluids for off‐shore oil exploration (Herman and Roberts, 2005). During 1‐hexadecene production in petrochemical plants, contaminated wastewater is generated, which can be treated by anaerobic digestion. This leads to the production of methane that is stored and used as biofuel. Methanogenic degradation of 1-hexadecene is poorly described, and only two enrichment cultures degrading this compound were reported (Schink, 1985). Methanogenic archaea resembling Methanospirillum and Methanosaeta could be identified, but no information on the bacterial composition was reported. The microbiology and biochemistry of aliphatic hydrocarbons degradation under methanogenic conditions have been mainly studied with hexadecane as model compound, a saturated C16 straight‐chain hydrocarbon. In this work, enrichment cultures with 1-hexadecene or hexadecane were started using anaerobic sludge as inoculum, with no previous adaptation to petroleum hydrocarbons.[2]

In our work, eight different operational taxonomic units (OTU) were assigned to Syntrophaceae sharing only 91 to 98% identity with each other, which suggests that different microorganisms belonging to this family were present in the enrichment cultures. Those sequences were 83 to 84% identical to a clone sequence from cold marine sediments  and 76 to 78% identical to a Smithella clone sequence (NCBI nucleotide accession KF824850). These identity percentages are low, which reflects the poor knowledge on the microbiology of anaerobic 1‐hexadecene degradation. This study shows that the degradation of 1-hexadecene by a non‐adapted methanogenic community is feasible, and can be considerably enhanced by the addition of extra electron donors. Yeast extract and lactate accelerated 1‐hexadecene degradation, increasing methane production rates up to 7 and 3 times respectively. Addition of M. formicicum did not improve methane production from 1‐hexadecene. Syntrophic bacteria and hydrogenotrophic methanogens were enriched in 1‐hexadecene‐degrading cultures, showing the syntrophic nature of this conversion. In cultures where Syntrophus and Smithella‐like microorganisms were detected, 1-hexadecene degradation was observed, while in cultures where these bacteria were not detected, no degradation occurred, suggesting their involvement in 1‐hexadecene degradation. The potential for a faster bioremediation strategy and bioenergy recovery in alkene‐contaminated systems is highlighted.

References

[1]Paulo AMS, Salvador AF, Alves JI, Castro R, Langenhoff AAM, Stams AJM, Cavaleiro AJ. Enhancement of methane production from 1-hexadecene by additional electron donors. Microb Biotechnol. 2018 Jul;11(4):657-666. doi: 10.1111/1751-7915.12886. Epub 2017 Dec 7. PMID: 29215212; PMCID: PMC6011941.

[2]Mou Y, Meng J, Fu X, Wang X, Tian J, Wang M, Peng Y, Zhou L. Antimicrobial and antioxidant activities and effect of 1-hexadecene addition on palmarumycin C2 and C3 yields in liquid culture of endophytic fungus Berkleasmium sp. Dzf12. Molecules. 2013 Dec 13;18(12):15587-99. doi: 10.3390/molecules181215587. PMID: 24352015; PMCID: PMC6270283.