Tert-Butyl chloride

Tert-Butyl chloride
IUPAC name	2-chloro-2-methylpropane
Other names	1,1-dimethylethyl chloride 1-chloro-1,1-dimethylethane 2-chloroisobutane 2-methyl-2-chloropropane chlorotrimethylmethane trimethylchloromethane t-butyl chloride tert-butyl chloride t-BuCl UN 1127
Identifiers
InChI	InChI=1/C4H9Cl/c1-4(2,3)5/h1-3H3
CAS number	[507-20-0]
EC number	208-066-4
RTECS	TX5040000
PubChem	10486
SMILES	CC(C)(C)Cl
Properties
Chemical formula	C4H9Cl
Molar mass	92.57 g/mol
Appearance	Colorless liquid
Density	0.84 g cm−3
Melting point	−26 °C
Boiling point	51 °C
Solubility in water	Sparingly sol in water, miscible with alcohol and ether
Vapor pressure	34.9 kPa (20 °C)
Hazards
EU classification	Flammable (F)
R-phrases	Template:R12, Template:R36/37/38
S-phrases	Template:S7, Template:S9, Template:S16, Template:S29, Template:S33
NFPA 704
Flash point	−9 °C (open cup) −23 °C (closed cup)
Autoignition temp.	540 °C
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

tert-Butyl chloride is a colorless, liquid organic compound at room temperature. It is sparingly soluble in water, with a tendency to undergo spontaneous solvolysis when dissolved into it. The compound is flammable and volatile, and its main use is as a starting molecule to carry out nucleophilic substitution reactions, to produce different substances, ranging from alcohols to alkoxide salts.

When tert-butyl chloride is dissolved in water, a polar and protic solvent, the bulky chloride substituent is carried away by it, and isolated from the aliphatic chain, causing an heterolitic rupture of the compound, giving rise to a carbocation which eventually becomes a tertiary alcohol after a water molecule reacts with it, releasing hydrochloric acid as the final product. If a different, stronger nucleophilic agent is present at the moment of reaction, reaction product may not be an alcohol, but a tertiary carbon with the nucleophile as a substituent.

Synthesis

tert-Butyl chloride can be synthesized in the laboratory by the S_N1 reaction of tert-Butanol with concentrated hydrochloric acid, as shown below.

Step 1	Step 2	Step 3
The acid protonates the alcohol, forming a good leaving group (water).	Water leaves the protonated t-BuOH, forming a relatively stable tertiary carbocation.	The chloride ion attacks the carbocation, forming t-BuCl.

The overall reaction, therefore, is:

Because tert-butanol is a tertiary alcohol, the relative stability of the tert-butyl carbocation in the Step 2 allows the S_N1 mechanism to be followed, whereas a primary alcohol would follow an S_N2 mechanism.

See also

• Isobutane

External links

• Safety MSDS data
• Preparation 2-chloro-2-methylpropane
• http://www.cerlabs.com/experiments/10875407331.pdf