Dimethylzinc
| Names | |
|---|---|
| IUPAC name
Dimethylzinc
| |
| Other names
Dimethyl zinc
DMZ | |
| Properties | |
| ZnC2H6 Zn(CH3)2 | |
| Molar mass | 95.478 g/mol |
| Appearance | Colorless volatile liquid |
| Odor | Disagreeable, garlic-like |
| Density | 1.33 g/cm3 (20 °C) (pure)[1] 0.931 g/cm3 (2 M solution in toluene) (25 °C) |
| Melting point | −42 °C (−44 °F; 231 K) |
| Boiling point | 46 °C (115 °F; 319 K) |
| Reacts | |
| Solubility | Reacts with alcohols, bases, carboxylic acids, esters, mineral acids Miscible with benzene, diethyl ether, hexane, toluene, xylene |
| Vapor pressure | 376 mmHg at 25 °C |
| Thermochemistry | |
| Std enthalpy of
formation (ΔfH |
50.6 kJ/mol |
| Hazards | |
| Safety data sheet | Sigma-Aldrich (2 M solution in toluene) |
| Flash point | -17 °C (1.4 °F; 256 K) |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Dimethylzinc, also known as zinc methyl, DMZ or DMZn, is an organometallic compound with the chemical formula Zn(CH3)2 or Zn(Me)2.
Contents
Properties
Chemical
Dimethylzinc ignites spontaneously in air at standard conditions, burning with a bluish flame.
- Zn(CH3)2 + 8 O2 → ZnO + 2 CO2 + 3 H2O
It will also hydrolyze in contact with water.
Dimethyl zinc can slowly oxidize in air, if kept below its autoignition temperature to yield methylzinc methylate (CH3ZnOCH3).[2]
The compound decomposes above 200-215 °C, yielding very pure zinc metal.[3]
Physical
Dimethylzinc is a colorless volatile liquid, with a disagreeable odor, described as "garlic-like" that immediately ignites in contact with air. It reacts with all protic solvents, but is very soluble in many hydrocarbon solvents, like alkanes and aromatics.
Availability
Dimethylzinc is sold by chemical suppliers, as solution, usually in hexane or toluene, which are much safer than the pure compound.
Preparation
Dimethylzinc can be prepared by reacting methyl iodide with zinc metal at 150-160 °C, or with a sodium-zinc alloy, at 45-50 °C, in diethyl ether.[4][5]
- 2 Zn + 2 CH3I → Zn(CH3)2 + ZnI2
- Zn + 2 Na + 2 CH3I → Zn(CH3)2 + 2 NaI
Copper can also be used to activate the zinc.[6]
Projects
- Demonstration of pyrophoricity
- Methylating agent
Handling
Safety
Dimethylzinc is highly pyrophoric and thus a severe fire hazard. Combustion generates white zinc oxide fumes, that are harmful for lungs if inhaled. In case of a fire, sand or class D fire extinguishers are used to put out the fire.
Storage
Dimethylzinc is best kept as solution, in hexane, in a glass bottle with a special silicone rubber septum and kept in a fridge or freezer.
Disposal
Dimethylzinc is extremely difficult and dangerous to safely neutralize. One could simply remotely detonate an old bottle in a firing range or some other abandoned polluted/industrial area. Or just take it to the disposal centers if this route is not acceptable.
A way to safely neutralize the hexane solution of dimethylzinc involves connecting the bottle to an argon line, then very carefully slowly inject ethanol inside the bottle, dropwise and monitor the temperature of the bottle. Eventually, all the dimethylzinc would have hydrolyzed, with the remaining zinc precipitate settling at the bottom of the bottle. The liquid is checked again to verify that all the DMZ has been destroyed, then the content is poured and either incinerated or if possible recycled. This route however, is very dangerous and should not be done by amateurs!
References
- ↑ Allen et al.; Journal of the Chemical Society; (1965); p. 5476,5478-5480
- ↑ Budavari, S. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 1996., p. 552
- ↑ Yoshikawa Akihiko; Physica B: Condensed Matter (Amsterdam); vol. 185; (1993); p. 50 - 64 ; (from Gmelin)
- ↑ Frankland; Justus Liebigs Annalen der Chemie; vol. 85; (1853); p. 360
- ↑ Wagner; Journal fuer Praktische Chemie (Leipzig); vol. <2>44; (1891); p. 261 Anm.
- ↑ Renshaw; Greenlaw; Journal of the American Chemical Society; vol. 42; (1920); p. 1474
Relevant Sciencemadness threads
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- Zinc compounds
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- Organozinc compounds
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- Materials that react with water
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