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HCTU Structural Formula V2.svg
IUPAC name
O-(1H-6-Chlorobenzotriazole-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate
Other names
2-(6-Chloro-1H-benzotriazole-1-yl)-1,1,3,3-tetramethylaminium hexafluorophosphate
3D model (JSmol)
ECHA InfoCard 100.116.975 Edit this at Wikidata
EC Number
  • 608-825-3
  • InChI=1S/C11H15ClN5O.F6P/c1-15(2)11(16(3)4)18-17-10-7-8(12)5-6-9(10)13-14-17;1-7(2,3,4,5)6/h5-7H,1-4H3;/q+1;-1
  • CN(C)C(=[N+](C)C)ON1C2=C(C=CC(=C2)Cl)N=N1.F[P-](F)(F)(F)(F)F
Molar mass 413.69 g·mol−1
Appearance White to off white powder
Melting point >185 °C
GHS labelling:
GHS02: FlammableGHS07: Exclamation mark
H228, H302, H315, H319, H335
P210, P240, P241, P261, P264, P270, P271, P280, P301+P312, P302+P352, P304+P340, P305+P351+P338, P312, P321, P330, P332+P313, P337+P313, P362, P370+P378, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

HCTU is an aminium coupling reagent used in peptide synthesis. It is analogous to HBTU.[1] The HOBt moiety has a chlorine in the 6 position which improves reaction rates and the synthesis of difficult couplings[2][3]


  1. ^ Marder, Oleg; Shvo, Youval; Albericio, Fernando (2003-08-12). "HCTU and TCTU: New Coupling Reagents — Development and Industrial Aspects". ChemInform. 34 (32). doi:10.1002/chin.200332258. ISSN 1522-2667.
  2. ^ Hood, Christina A.; Fuentes, German; Patel, Hirendra; Page, Karen; Menakuru, Mahendra; Park, Jae H. (2008-01-01). "Fast conventional Fmoc solid-phase peptide synthesis with HCTU". Journal of Peptide Science. 14 (1): 97–101. CiteSeerX doi:10.1002/psc.921. ISSN 1099-1387. PMID 17890639. S2CID 24163278.
  3. ^ Sabatino, Giuseppina; Mulinacci, Barbara; Alcaro, Maria C.; Chelli, Mario; Rovero, Paolo; Papini, Anna M. (2002-03-01). "Assessment of new 6-Cl-HOBt based coupling reagents for peptide synthesis. Part 1: Coupling efficiency study". Letters in Peptide Science. 9 (2–3): 119–123. doi:10.1007/bf02576873. ISSN 0929-5666. S2CID 29545816.