Heneicosane

Description

Heneicosane (also known as n-Heneicosane) is a potential organic phase-change material (PCM) used for thermal energy storage^[1]. In its pure form, it has a melting point of 313.55 K (approximately 40.4 °C) and offers advantages such as good stability, low supercooling and low cost. However, due to its relatively low thermal conductivity, it is often combined with highly thermally conductive fillers (such as graphene) to form composite materials, which are used in solar thermal energy storage, passive cooling of electronic devices, and waste heat recovery systems.

Chemical Properties

white waxy solid

Uses

Heneicosane is a long chain saturated aliphatic hydrocarbon found in coal tars and fossil organic matter. Heneicosane has a high flashpoint which makes it an inefficient fuel for use in the petrochemical industry. Heneicosane is usually present in the form of paraffin wax.

Definition

ChEBI: An alkane that has 21 carbons and a straight-chain structure. It has been isolated from plants like Periploca laevigata and Carthamus tinctorius.

Synthesis Reference(s)

Tetrahedron Letters, 17, p. 2643, 1976 DOI: 10.1016/S0040-4039(00)91757-X

General Description

Crystals.

Air & Water Reactions

Insoluble in water.

Reactivity Profile

Saturated aliphatic hydrocarbons, such as N-HENEICOSANE, may be incompatible with strong oxidizing agents like nitric acid. Charring of the hydrocarbon may occur followed by ignition of unreacted hydrocarbon and other nearby combustibles. In other settings, aliphatic saturated hydrocarbons are mostly unreactive. They are not affected by aqueous solutions of acids, alkalis, most oxidizing agents, and most reducing agents. When heated sufficiently or when ignited in the presence of air, oxygen or strong oxidizing agents, they burn exothermically to produce carbon dioxide and water.

Synthesis

Preparation method for one-time preparation of n-hexadecane in the following steps:

(1). Mix 1510.5 g (10 mol) of n-pentyl bromide and 3053.5 g (10 mol) of n-hexadecyl bromide to form a bromoalkane mixture, and set aside;

(2). Weigh 483 g (21 mol) of metallic sodium and cut it into small thin strips with an area of about 1 x 3 cm2, and set aside;

(3). In the reaction kettle put 50g of bromoalkane mixture as well as 20g of sodium metal, stirring to raise the temperature to 80 , relying on the reaction heating, and maintain the reaction temperature of 120 , and constantly dropwise addition of the remaining bromoalkane mixture, and add the sodium metal, maintain the micro reflux state, the addition is completed, control the temperature at 140 , constant temperature for 2 hours;

(4). Sequentially add 400 g of 95% ethanol as well as 1000 ml of water, split the organic matter, washed with water to neutral, dried with anhydrous magnesium sulfate, distilled to collect 260 ~ 280 fractions, the fraction plus 600 g of concentrated potassium sulfate washed to the acid layer light yellow, washed with water the organic phase to neutral, drying, through the fractional distillation column to collect 500 g of 96% of the n-decane, 600 g of 98% of the n-xyloxanes, the resulting n-alkane content of 96% to 98%.

Said n-pentane and n-hexadecyl bromide molar ratio is 1:1, the reactor is a three-ported flask consisting of a stirrer, a separatory funnel and a reflux condenser, said strong oxidizing agent is concentrated sulfuric acid or acidic potassium permanganate.

References

[1] Sinaga, R. (2026). Thermal Performance Enhancement of Heneicosane as Thermal Energy Storage Material: A Molecular Dynamic Study. Energy Storage, 8 1. https://doi.org/10.1002/est2.70334