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Base resin

Wang resin for Fmoc C-terminal acids

p-Alkoxybenzyl alcohol linker on polystyrene–DVB. The workhorse support for Fmoc SPPS of peptides with a free C-terminal carboxylic acid, cleaved in concentrated TFA with scavengers.

All resins

0.3–1.2

mmol/g loading

100–200

mesh (typical)

1%

DVB crosslinking

TFA

cleavage cocktail

C-acid

terminus delivered

Linker chemistry

Wang resin carries a 4-alkoxybenzyl alcohol handle. The first Fmoc-amino acid is esterified onto the benzyl alcohol; subsequent cycles follow standard Fmoc/tBu SPPS. Final cleavage with TFA releases the peptide as a C-terminal acid and simultaneously removes acid-labile side-chain protecting groups.

Compared with 2-CTC, Wang requires stronger acid and is less suitable when you need a fully protected fragment or when the C-terminal residue is prone to diketopiperazine during Fmoc deprotection. It remains the default when you want a free acid after a standard TFA workup.

Typical specifications

Lot certificates list measured loading, mesh and swelling. Ranges below are indicative of commercial polystyrene Wang resins.

Matrix

Polystyrene–DVB

1% DVB typical for lab scale

Linker

p-Alkoxybenzyl alcohol (Wang)

Acid-labile benzyl ester

Loading

0.3–1.2 mmol/g

Lower loading for long / difficult sequences

Mesh

100–200 or 200–400

Coarser mesh for large reactors

Swelling (DCM)

~4–6 mL/g

Check DMF/NMP for SPPS

Cleavage

95% TFA + scavengers

1–3 h typical; residue-dependent

C-terminus

Carboxylic acid

Not for C-terminal amides

Figures are indicative industry-typical values. Lot- and project-specific data appear on the quotation and certificate of analysis.

C-terminal residue considerations

First-residue choice affects racemization on loading and diketopiperazine risk during Fmoc deprotection of dipeptides on Wang.

C-terminal residueRiskGuidance
Pro, GlyDKP formationPrefer 2-CTC or load as pre-formed dipeptide; minimize piperidine contact time
Cys, HisRacemization on loadingUse pre-loaded Wang or mild esterification protocols; avoid strong bases
Asp, GluSide-chain ester migrationStandard tBu protection; monitor aspartimide in Asp-Gly motifs
Standard AALowWang is appropriate for routine C-terminal acids

Figures are indicative industry-typical values. Lot- and project-specific data appear on the quotation and certificate of analysis.

Indicative cleavage protocol

Always optimize scavengers to the sequence (Trp, Met, Cys, Arg). The cocktail below is a common starting point.

  1. 01

    Wash the peptidyl-resin with DCM, then dry under vacuum or nitrogen.

  2. 02

    Treat with TFA / TIS / water (95:2.5:2.5) or TFA / EDT / water / TIS as required by the sequence, ~10 mL/g resin.

  3. 03

    Agitate 1–3 hours at room temperature; filter and wash the resin with fresh TFA.

  4. 04

    Precipitate the peptide in cold diethyl ether or MTBE, centrifuge, wash, and lyophilize from aqueous TFA or AcOH.

  5. 05

    Confirm identity and purity by HPLC and LC-MS before further purification.

How teams use Wang resin

01

Select loading and mesh

Lower loading (≤0.5 mmol/g) for sequences >30 residues or aggregation-prone stretches; higher loading for short peptides where throughput matters.

02

Load or buy pre-loaded

Esterify the first Fmoc-AA in-house, or start from pre-loaded Fmoc-AA-Wang to skip racemization-prone first coupling.

03

Assemble by Fmoc SPPS

Standard DIC/Oxyma or HATU protocols in DMF or NMP; double-couple difficult positions as needed.

04

Cleave, purify, document

TFA cleavage with scavengers, RP-HPLC purification, and a COA with loading and residual solvent data for the resin lot used.

What you receive

  • Resin lot with stated loading (mmol/g) and mesh
  • Certificate of analysis: appearance, loading assay, % DVB where reported
  • Storage guidance (cool, dry; protect from light and moisture)
  • Optional: swelling data in DCM/DMF on request
  • Quote reference tied to mesh, loading band and pack size

Frequently asked questions

No. Wang releases a carboxylic acid. For C-terminal amides use Rink Amide (AM or MBHA) or Sieber Amide for mild cleavage of protected amides.

Related

2-Chlorotrityl (2-CTC)

Trityl chloride linker on polystyrene–DVB forms acid-labile benzyl esters. 2-CTC is the default when you need protected peptide fragments, acid-sensitive motifs, or lower diketopiperazine risk at the C-terminus than on Wang.

View details

Pre-loaded Wang

Fmoc-amino acids esterified on Wang with lot-documented loading. Skips the racemization-prone first coupling and accelerates campaigns where the C-terminal residue is His, Cys, or otherwise sensitive to manual loading.

View details

Rink Amide AM / MBHA

para-(Rink amide) benzyl ester supports deliver peptides with C-terminal CONH2 after TFA cleavage. Choose AM (aminomethyl) for standard lengths or MBHA (4-methylbenzhydrylamine) when higher swelling and softer aggregation help long or difficult sequences.

View details

Ethyl & Methyl Indole Resins

Indole-derived linkers on polystyrene enable C-terminal N-ethyl and N-methyl carboxamides after TFA cleavage—motifs common in GnRH analogs such as leuprolide. Chemistry differs from Rink: first coupling to the linker is inefficient under carbodiimide alone; HATU (or similar uronium) is required.

View details
Next step

Ready to specify this for your program?

Share sequence, scale and documentation needs. We reply with indicative specs and a project-specific quotation.