The preparation methods of dodecane

Background

Dodecane is an organic compound with a chemical formula of C12H26 and a molecular weight of 170.33. Dodecane is a colorless liquid with a melting point of -9.6°C, a boiling point of 216.3°C, a flash point of 71°C, a density of 0.753g/cm3, and a vapor pressure of 0.133kPa/47.8°C. Insoluble in water, soluble in ethanol, ether, acetone, chloroform, carbon tetrachloride and benzene. Used as a reference material for organic synthesis intermediates, solvents and chromatographic analysis[1].

Properties and stability

The combustion products of dodecane are generally carbon monoxide and carbon dioxide. Carbon monoxide can combine with platelets in human blood and cause human poisoning. Therefore, attention should be paid to preventing human poisoning when dodecane is burned. Dodecane is stable at normal temperature and pressure, but avoids contact with strong oxides.

The preparation method of dodecane

In a dry reaction flask equipped with a stirrer, a thermometer, and a reflux condenser (with a calcium chloride drying tube), add 50 mL of hexamethylphosphoramide (HMPA), n-dodecyl p-toluenesulfonate (2) 6.8 g (0.0201mol), sodium cyanoborohydride ① 5.02g (0.08mol). The reaction was carried out at 80 °C for 2 h with stirring. After cooling, 50 mL of water was added and extracted three times with n-hexane. The organic extracts were combined, washed twice with water, dried over anhydrous magnesium sulfate, distilled under reduced pressure, and the fractions at 79-81°C/1.86KPa were collected to obtain n-dodecane (1) 2.5-2.65g, yield 79%-81 %. Note: ①Reduction of alkyl halides and sulfonates with sodium cyanoborohydride in hexamethylphosphoramide is a convenient method for preparing alkanes with high selectivity. Other functional groups in the molecule such as carboxyl, carboxylate, cyano group, nitro group, amido group, carbonyl group, oxiranyl group, etc. are not affected. [2]

Picture 1 preparation method by hexamethylphosphoramide

Use 23g (1.0mol) sodium metal with 82.5g (62mL, 0.5mol) 1-bromohexane (2) or 99g (65.5mL, 0.5mol) 1-bromopentane according to the above-mentioned operation method for preparing n-octane, The fractions at 94°C/174KPa were collected to obtain about 37g of n-decane (1) with a yield of 87%.

Picture 2 preparation method by 1-bromohexane

How to store dodecane

Dodecane needs to be sealed and stored in a cool, dry place. And make sure that the workplace containing dodecane has good ventilation. Keep away from sources of ignition when storing and using dodecane. Store away from oxidizing agents.

Health hazards of dodecane

The main routes of entry of dodecane include inhalation, ingestion, and percutaneous absorption. May be harmful and irritating when inhaled, ingested or absorbed through the skin.

Toxicological information

Dodecane is irritating, and 50ul/24H dodecane will produce moderate irritation in the dodecane transdermal experiment in rabbits. When inhaled by rabbits, acute poisoning events with LC50: >142ppm/8H occur.

Hazardous properties of dodecane

The vapor of dodecane will form an explosive mixture with air, which may cause fire and explosion in case of open flame, high heat or contact with oxidant. Dodecane will be decomposed by high heat, thereby releasing toxic fumes.

Emergency release treatment

Evacuate personnel from the leaked contaminated area to a safe area, and prohibit irrelevant personnel from entering the contaminated area. It is recommended that emergency responders wear masks, goggles, and work clothes. Absorb with sand, shovel into buckets, and transport to waste disposal sites. Scrub the spilled contaminated area with water, and put the diluted sewage into the waste water system. If there is a large amount of leakage, use the embankment to contain it, and then collect, transfer, recycle or waste it after harmless treatment.

Protective measures

Respiratory Protection: Masks should be worn.

Eye Protection: Generally, no special protection is required.

Protective clothing: Wear work clothes.

Hand Protection: Wear protective gloves.

Others: Smoking, eating and drinking are prohibited at the workplace. After work, shower and change. Practice good hygiene.

First-aid

Skin Contact: Wash thoroughly with soap and water. seek medical attention.

Eye Contact: Pull eyelids and rinse with running water for 15 minutes. seek medical attention.

Inhalation: Remove from site to fresh air. seek medical attention.

Ingestion: If swallowed by mistake, drink appropriate amount of warm water and induce vomiting. seek medical attention.

Extinguishing methods: anti-solvent foam, carbon dioxide, dry powder.

Reference

1 Schutte W J, Sluyters-Rehbach M, Sluyters J H. Aggregation of an octasubstituted phthalocyanine in dodecane solution[J]. The Journal of Physical Chemistry, 1993, 97(22): 6069-6073.

2 Furniss B S，Hannaford A J，Rogers V，et al. Vogel’s Texbook of Practical Chemistry. Longman London and New YorK. Fourth edition，1978：:325. 2、Hutohins R O，Milewski C A and Maryunoff B E. Org Synth，1973,53:107.