Capping A (THF / lutidine / acetic anhydride; V / V / V = 80 / 10 / 10)

For each synthesis cycle, up to 1 to 2% of free 5’-hydroxy groups remain after the phosphoramidite coupling step has been completed. By running a subsequent „Capping“ step using an anhydride, these free hydroxyl groups are converted to acetates and are hindered from further chain elongation and formation of long oligonucleotides with incorrect sequences.

For optimal acetylation, a solution of acetic anhydride in Tetrahydrofuran or acetonitrile (Capping A) will be mixed in situ during reaction with a catalytic acting solution of N-methylimidazole (Capping B). Additives such as pyridine and lutidine function as mild bases to enhance the efficiency of the capping reaction.

Product Name: Capping A
Description: 80% Tetrahydrofuran, 10% 2,6-Lutidine and 10% Acetic anhydride (v/v/v)
CAS Number: Tetrahydrofuran 109-99-9, 2,6-Lutidine 108-48-5, Acetic anhydride 108-24-7
Appearance: Clear Solution
Refractive Index: 1,412 – 1,416
Water content: ≤ 100.0 ppm

Shipping: Ambient
Storage: Ambient

Application Note
Capping reagent for nucleic acid synthesis.

Cas Number: 109-99-9

Einecs Number: 203-726-8

HS Code / Commodity Code: 38249992

UN Number: 2924

Hazard Class: 3

Packing Group: 2

Hazard Phrases: H302+H332,H315,H318,H335,H351

Prec Phrases: P210,P280,P301+P312,P304+P340,P312,P305+P351+P338,P308+P313