Di-tert-butyl dicarbonate

Di-tert-butyl dicarbonate

Names
IUPAC name Di-t-butyl dicarbonate
Other names Di-tert-butyl pyrocarbonate Boc anhydride Boc2O
Identifiers
CAS Number	24424-99-5 Y
3D model (Jmol)	Interactive image
ChEBI	CHEBI:48500 Y
ChemSpider	81704 Y
ECHA InfoCard	100.042.021
PubChem CID	90495
InChI InChI=1S/C10H18O5/c1-9(2,3)14-7(11)13-8(12)15-10(4,5)6/h1-6H3 Y Key: DYHSDKLCOJIUFX-UHFFFAOYSA-N Y InChI=1/C10H18O5/c1-9(2,3)14-7(11)13-8(12)15-10(4,5)6/h1-6H3 Key: DYHSDKLCOJIUFX-UHFFFAOYAG
SMILES O=C(OC(=O)OC(C)(C)C)OC(C)(C)C
Properties
Chemical formula	C10H18O5
Molar mass	218.25 g·mol−1
Appearance	Colorless solid or oil
Density	0.95 g·cm−3
Melting point	22 to 24 °C (72 to 75 °F; 295 to 297 K)
Boiling point	56 to 57 °C (133 to 135 °F; 329 to 330 K) (0.5 mmHg)
Solubility in water	Insol
Solubility in other solvents	Soluble in most organic solvents
Hazards
Main hazards	Very toxic on inhalation T+, LC50 = 100 mg/m3 (4 hr, rat)
Related compounds
Related compounds	Ethyl chloroformate Phosgene Diethyl pyrocarbonate Dimethyl dicarbonate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Di-tert-butyl dicarbonate is a reagent widely used in organic synthesis. Since this compound can be regarded formally as the acid anhydride derived from a tert-butoxycarbonyl (Boc) group, it is commonly referred to as "Boc anhydride." This pyrocarbonate reacts with amines to give N-tert-butoxycarbonyl or so-called Boc derivatives. These carbamate derivatives do not behave as amines, which allows certain subsequent transformations to occur that would be incompatible with the amine functional group. The Boc group can later be removed from the amine using moderately strong acids (e.g., trifluoroacetic acid). Thus, Boc serves as a protective group, for instance in solid phase peptide synthesis. Boc-protected amines are unreactive to most bases and nucleophiles, allowing for the use of the fluorenylmethyloxycarbonyl group (Fmoc) as an orthogonal protecting group.

Di-tert-butyl dicarbonate is inexpensive, so it is usually purchased. Classically, this compound is prepared from tert-butanol, carbon dioxide, and phosgene, using DABCO as a base:

This route is currently employed commercially by manufacturers in China and India. European and Japanese companies use the reaction of sodium tert-butoxide with carbon dioxide, catalysed by p-toluenesulfonic acid or methanesulfonic acid. This process involves a distillation of the crude material yielding a very pure grade.