Benzyl chloroformate

Benzyl chloroformate
Names
Preferred IUPAC name
Benzyl carbonochloridate
Other names
Benzyl chloroformate
Benzyloxycarbonyl chloride
Z-Chloride
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.007.205
Properties
C8H7ClO2
Molar mass 170.59 g·mol−1
Density 1.195 g/cm3
Boiling point 103 °C (217 °F; 376 K) (20 Torr)
Hazards
Safety data sheet External MSDS
C N Xn
R-phrases (outdated) R34, R50/53
S-phrases (outdated) (S1/2), S26, S45, S60, S61
Flash point 80 °C (176 °F; 353 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Benzyl chloroformate is the benzyl ester of chloroformic acid. It is also known as benzyl chlorocarbonate and is an oily liquid whose color is anywhere from yellow to colorless. It is also known for its pungent odor. When heated, benzyl chloroformate decomposes into phosgene and if it comes in contact with water it produces toxic, corrosive fumes.

Preparation

It is prepared in the lab by dropping benzyl alcohol into liquid phosgene at −20 °C. Phosgene is used in excess to minimise the production of the carbonate.[1]

Uses

Benzyl chloroformate is used in organic synthesis for the introduction of the carboxybenzyl (abbreviated Cbz or Z) protecting group for amines:

The newly formed Cbz protecting group can be removed under reductive conditions. Typically hydrogen gas and activated palladium on carbon are used.

References

  1. ↑ Hough, L.; Priddle, J. E. (1961). "Carbonate derivatives of methyl α-D-mannopyranoside and of D-mannose". J. Chem. Soc. 1961: 3178–3181. doi:10.1039/JR9610003178.


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