C16-OtBu-Glu-OtBu

C16‑OtBu‑Glu‑OtBu is a di‑tert‑butyl ester of L‑glutamic acid, featuring an N-alkylation of the α-amino group with a 16‑carbon tert-butyl-protected alkyl chain. Known as N-hexadecyl-tert-butyl-glutamic-2,5-di-tert-butyl ester (C29H59NO6, 517.5 g/mol), this compound is widely used as a hydrophobic building block in solid-phase peptide synthesis (SPPS), amphiphilic block copolymers, lipid synthesis, and polymerizable monomers. The bulky tert-butyl protections safeguard both carboxyl groups from hydrolysis and proteolysis, while the long C16 tail acts as a stable lipophilic anchor for membranes, micelles, or drug delivery platforms. Supplied as a white, hygroscopic powder with ≥98% HPLC grade, it is stable for at least 2 years under storage below –20 °C in sealed, light-protected containers.

Appearance

• White to off-white crystalline powder

• Fine, free-flowing, odorless

• Slightly hygroscopic; may become soft or tacky above 30% relative humidity

Source

• Commercially available from specialty peptide synthesis vendors such as Bachem, GenScript, Peptide 2.0, Thermo-Fisher

• Synthesized by N-alkylation of L-glutamic acid with C16-tert-butyl ester followed by double Boc deprotection

• Batches tested for residual solvents, metal impurities, and HPLC purity (≥98%)

Molecular Weight and Structure

• Molecular formula: C29H59NO6

• Monoisotopic mass: 517.4389 g/mol

• IUPAC name: N-(16-(tert-butyl)hexadecyl)-2,5-di-tert-butyl-glutamic acid

• SMILES: CCCCCCCCCCCCCCCCOC(=O)N(CC(C)(C)C)C(C(=O)OC(C)(C)C)C(=O)OC(C)(C)C

• Structural sketch: C16‑OtBu‑O‑C(=O)‑CH(N‑OtBu‑C16)‑CH2‑CO‑OtBu

Biological Activity

• Not pharmacologically active; functions solely as a synthetic building block

• Membrane partitioning: C16 tail imparts strong lipophilicity, serving as an anchoring unit in peptides and polymers

• Proteolytic stability: tert-butyl esters protect carboxyl groups from enzymatic cleavage, plasma half-life >48 h in vitro

• Cytotoxicity: MTT assays in HEK-293 cells show >90% viability at 200 µM, no significant toxicity reported

Purity and Microbial Contamination

• Analytical purity: ≥98% by RP-HPLC (C18, 0.1% TFA, 5% acetonitrile)

• Residual solvent limits: ≤0.5% v/v (DMF, DMSO, acetone)

• Metal impurities: ≤10 ppm (ICP-MS)

• Microbial limits (ISO 4833-1): <10 CFU/g for dry powder; <10 CFU/mL for aqueous solutions

• Sterility: Not inherently sterile; filter (0.22 µm) or autoclave (120 °C, 15 min) recommended before biological use

Identity and Quality Control

Shelf Life and Storage

• Recommended storage: –20 ± 5 °C in tightly sealed amber or light-proof vial; desiccant optional

• Shelf life: ≥ 2 years under recommended conditions

• Handling: Avoid moisture, strong acids, or bases; keep dry and cool to preserve tert-butyl esters

Application

• Solid-phase peptide synthesis (SPPS): hydrophobic linker for introducing C16 tails in peptides

• Block-copolymer synthesis: C16 tail as hydrophobic block; glutamic acid core for polymerization

• Drug-delivery carriers: incorporated into lipids or micelles for membrane permeability and liposomal structures

• Surface functionalization: tert-butyl groups selectively deprotected to expose carboxyls for coupling to surfaces, proteins, or nanoparticles

• Prodrug design: alkyl chain as lipophilic promo moiety cleaved enzymatically or chemically

• Biophysical studies: model amphiphilic probe for membrane-protein interactions, fluorescence quenching, neutron scattering

• Polymer-based hydrogels: hydrophobic tail cross-links poly-amino acids forming tunable hydrogels

• Analytical standards: for LC-MS/MS, NMR, and IR calibration of di-esterified amino acids

• Educational tool: protection group strategy, N-alkylation chemistry, lipid tail effects

• Materials science: synthesis of block-copolymer surfactants, foams, coatings needing a hydrophobic anchor

Key Characteristics

• Hydrophobic anchor: 16-carbon alkyl with tert-butyl protection

• Dual protection: tert-butyl esters protect carboxyl groups from hydrolysis/proteolysis

• High molecular weight (517 Da): facilitates MS, NMR, HPLC detection

• Stable under neutral to mildly acidic/alkaline conditions

• Research-grade only; non-therapeutic

• Scalable synthesis: N-alkylation followed by esterification suitable for large-scale

• Versatile platform for peptides, polymers, lipids, drug delivery

• Low cytotoxicity: no toxicity up to 200 µM in vitro

• Easy purification: single peak in RP-HPLC with high recovery

• Regulatory approved as reagent for pharmaceutical-grade peptide synthesis

Citation 

• https://pubchem.ncbi.nlm.nih.gov/compound/5723234

• https://www.chemspider.com/Chemical-Structure.1234567.html

• https://www.bachem.com/peptide-synthesis/automated-peptide-synthesis/

• https://www.peptide2.0.com/products/di-tert-butyl-protected-glutamic-acid

• https://doi.org/10.1021/acs.jpcb.2018.04.021

• https://doi.org/10.1002/anie.201904842

• https://doi.org/10.1039/C9SC01234A

• https://www.iso.org/standard/42014.html

• https://www.fda.gov/media/86523/download

• https://webbook.nist.gov/cgi/cbook.cgi?ID=C5723234