m-PEG9-t-butyl ester - ≥98%

Cat. No.: M596809

GRADE & PURITY ≥98%

Storage

Store at -20°C

Shipped In

Ice chest + Ice pads

Overview

m-PEG9-t-butyl ester is a PEG derivative containing a t-butyl ester. The t-butyl protecting group can be removed under acidic conditions. The hydrophilic PEG spacer increases the water solubility of a compound in aqueous media.

Specifications

Specifications & Purity

≥98%

Storage

Store at -20°C

Shipped In

Ice chest + Ice pads

This product requires cold chain shipping. Ground and other economy services are not available.

Purity

≥98%

Application Protocols

No manufacturer‑validated application protocols are provided for this specific SKU.

• General workflow examples (informational; adapt to your system):

  1. Deprotect to acid: Dissolve m‑PEG9‑tBu ester (e.g., 10–50 mg/mL) in DCM, add TFA (50–95% v/v), stir at RT 1–3 h. Evaporate, co‑evaporate with toluene, neutralize residue with NaHCO3(aq), extract with EtOAc, dry and concentrate.
  2. NHS activation: Dissolve the acid in DMF, add EDC·HCl (1.2 eq) and NHS (1.2 eq) at 0–5 °C, then warm to RT 1–2 h. Use in situ or isolate.
  3. Conjugation: Add amine substrate (1.2–2 eq) and DIPEA (2–3 eq), stir RT 2–16 h. Purify by precipitation or chromatography.

• Analytical checkpoints:

  • 1H NMR: Disappearance of tBu singlet confirms deprotection; downfield shift of PEG terminal methylenes after coupling.
  • MS (MALDI/ESI): Confirms mass increase consistent with coupling.

Note: These are literature‑style examples and not validated for this item. Optimize conditions for your substrate and consult SDS/CoA for handling specifics.

Biological Roles

This product is a synthetic PEG reagent and does not possess intrinsic biological activity. However, PEG segments influence biomolecular interactions.

• General/literature context (informational; not item-specific claims):
  • PEGylation reduces protein adsorption and opsonization due to steric repulsion and water structuring around the ethylene glycol repeats.
  • Short PEG linkers (n≈9) serve as flexible spacers that improve aqueous dispersion of nanomaterials and tune the distance between a surface and a bioactive ligand.
  • The tert‑butyl ester is a protecting group; after conversion to the acid and coupling to biomolecules (e.g., lysine amines), the PEG segment can modulate solubility and reduce aggregation.
  • Enzymatic metabolism: PEG backbones are generally resistant to typical metabolic pathways and are considered biologically inert at the oligomer scale in vitro; clearance and biodistribution depend on overall conjugate properties.

Research use only note: Per Product Data, this material is for research use only, not for use in humans or clinical diagnostics. No medical or therapeutic claims are made.

Buffer Applications

This compound is not a buffering agent and does not define a conjugate acid–base pair suitable for pH control. Therefore, traditional buffer recipes (pKa/pH windows) are not applicable.

• Practical guidance (general):
  • After deprotection to the carboxylic acid, coupling reactions often use mixed aqueous/organic buffers (e.g., MES pH 5.5–6.0 for EDC/NHS activation) or organic media with tertiary amines (DIPEA) for HATU/DIC chemistry. These buffers pertain to the reaction environment rather than the reagent acting as a buffer.
  • Solubilization in biological buffers: The tert‑butyl ester form may have limited water miscibility; dissolve first in DMSO or DMF and dilute into buffer if needed, ensuring final cosolvent <5–10% for bioassays.

For specific buffer compositions and pH control, refer to standard buffer systems (e.g., PBS, MES, HEPES) appropriate to your coupling chemistry.

Green Alternatives

Consider greener solvents and process choices when working with m-PEG9-t-butyl ester.

• Solvent choices (general guidance):

  • Prefer ethyl acetate, 2‑MeTHF, CPME, or IPA over chlorinated solvents when feasible (e.g., for extractions and crystallizations/triturations).
  • For couplings, dimethyl carbonate (DMC) or propylene carbonate can sometimes replace DMF/NMP; assess solubility and reactivity.

• Protection strategy:

  • Tert‑butyl ester is convenient but requires strong acid (TFA/HCl) for removal. If acid waste is a concern, consider benzyl esters (hydrogenolysis) or enzymatically cleavable esters for downstream processes; each has tradeoffs (catalyst use, selectivity).

• Energy and waste:

  • Conduct deprotections at ambient temperature when possible; TFA in DCM often proceeds rapidly without heating.
  • Minimize excess carbodiimide reagents; adopt recyclable coupling systems or uronium salts with lower urea waste where appropriate.

• Comparison table (informational):

  • TFA/DCM deprotection: Fast, room temp; generates acidic halogenated waste.
  • HCl/dioxane deprotection: Inexpensive; generates chloride waste, can be slower.
  • Solid‑phase scavengers: Reduce aqueous neutralization steps but add consumables.

Select options according to EHS constraints and product purity requirements; verify compatibility with your substrate.

Pharmaceutical Uses

No pharmacopeial status or excipient grade is provided for this item.

• Item-specific note: Grade/purity not specified; this product is designated for research use only (per Product Data) and not for human or clinical use.

• General/literature context (informational):

  • PEG motifs are widely used in formulation science as solubilizers, linkers, or spacers; short PEG linkers can modulate hydrophilicity of small molecules or polymers.
  • The tert‑butyl ester provides a storage‑stable, acid‑labile protection for a carboxyl function, enabling just‑in‑time generation of a reactive acid for conjugation to amine‑containing actives or excipients.
  • In process development (non‑clinical), PEGylated linkers are evaluated for impact on viscosity, phase behavior, and stability of prototype formulations or delivery vehicles.

Any application toward drug substance or product manufacture requires appropriate GMP sourcing, full characterization, and regulatory assessment; this listing does not constitute such qualification.

Physical Properties

• Item-specific properties (from Product Data):

  • Appearance: Not specified for this item; refer to CoA/Spec Sheet.
  • Molecular weight, formula: Not specified for this item; refer to CoA/Spec Sheet.

• General/literature expectations for m-PEG oligomers around n≈9 (informational, not specifications):

  • Physical state: typically a low‑melting waxy solid or viscous liquid, depending on polydispersity and end groups.
  • Solubility: high in polar organic solvents (DCM, DMSO, DMF, THF, MeOH, EtOH, acetonitrile); moderate to high in water once the tert‑butyl ester is removed (acid form increases hydrophilicity). The tert‑butyl ester end slightly reduces water solubility relative to the acid.
  • Hydrophilicity: strong due to PEG backbone; logP effectively low to moderate depending on termination (literature: PEG oligomers are amphiphilic, often used to solubilize hydrophobic motifs).
  • Boiling point/decomposition: oligomeric PEG derivatives typically do not have a sharp BP; they may decompose or exhibit broad distillation ranges under high vacuum (literature).
  • Hygroscopicity: PEG chains can absorb moisture; handling under dry conditions helps retain accurate mass and performance (general guidance).

Note: For exact numerical data (MP, density, refractive index, water content, UV cutoff), see the item’s CoA/Spec Sheet; not specified for this item.

Quality & Grades

• Item-specific grade/purity: Not specified for this item; refer to CoA/Spec Sheet.

• Interpreting quality for PEG reagents (general guidance):

  • Purity metrics: PEG oligomers are often specified by mass purity (HPLC/GC), polydispersity (Ð, via GPC), average molecular weight (Mn/Mw), and residual solvent or water content (KF). End‑group fidelity (≥95–98%) is critical for reproducible coupling yields; verify by 1H NMR end‑group integration and MALDI/ESI MS when available.
  • Stabilizers: Typically none are required for saturated PEG esters; if present (e.g., BHT), it will be declared on the CoA and may affect downstream oxidations.
  • Low UV background: For analytical or photochemical work, HPLC grade solvents and low‑UV PEG reagents reduce baseline drift; inquire if UV cutoff data are needed.
  • Trace metals/ionic content: Usually low in organic PEG reagents; when surface or electronic materials are involved, a “metals‑screened” or EL grade may be requested—confirm via CoA.
  • Acceptance testing suggestions: 1H/13C NMR for end‑group confirmation, FTIR (C=O ~1735 cm−1 for tert‑butyl ester), acid value after deprotection, and GPC to confirm the oligomer distribution.

Note: For this specific item, consult Aladdin’s CoA/Spec Sheet for definitive grade, purity, and analytical values.

Reaction & Applications

This reagent is a protected, monofunctional PEG linker widely used in materials science and bioconjugation workflows once the terminal tert‑butyl ester is deprotected to reveal the carboxylic acid.

• Item-specific applications (from Product Data): Not specified; category indicates Materials Science.

• General/literature applications (informational):

  • Latent carboxyl handle: Acidolysis (e.g., TFA) converts the tert‑butyl ester to m‑PEG9‑CO2H for amide formation with amines (EDC/NHS, HATU, or DIC/HOAt).
  • Surface modification: Grafting to amine‑functionalized oxides, polymers, or nanoparticles via amide linkages yields hydrophilic, protein‑resistant coatings; PEG9 provides nanometric spacing and reduces nonspecific adsorption.
  • Spacer/linker in conjugation: The PEG9 segment imparts flexibility and water compatibility when connecting dyes, haptens, or polymer blocks.
  • Polymer chemistry: Block copolymer synthesis (e.g., RAFT/ATRP initiators introduced after converting the acid to appropriate halides/RAFT agents), star or brush PEGylation via post‑polymer modification.
  • Micelle/assembly tuning: Introducing a short PEG block modulates CMC and particle size in amphiphiles.

• Practical tips:

  • Verify complete deprotection by disappearance of tert‑butyl singlet (~1.45 ppm) in 1H NMR and IR loss of tBu ester C–O stretch; carboxylic acid shows broad O–H and C=O ~1710–1725 cm−1.
  • For high‑yield couplings, generate NHS ester in situ (EDC/NHS, pH 5.5–6 in mixed aqueous/DMF) or use HATU/DIPEA in anhydrous DMF for purely organic systems.

Reaction Conditions

The following are general literature conditions for common operations with tert‑butyl PEG esters; they are guidance only and not product specifications.

• Deprotection (tBu ester → acid):

  • TFA in DCM (50–95% v/v TFA), 0–25 °C, 0.5–4 h; monitor by TLC or 1H NMR. Workup by co‑evaporation with toluene/MeOH to remove TFA, then neutralize and extract.
  • 4 M HCl in dioxane, 20–25 °C, 2–16 h; suitable when avoiding TFA. Rinse with dry ether/EtOAc and neutralize under controlled conditions.

• Amide coupling (acid form):

  • EDC·HCl (1.1–1.5 eq) + NHS (1.2 eq) in DMF or DMF/H2O (pH 5.5–6.0 with MES), 0–25 °C, 1–16 h; then add amine (1.2–2.0 eq) with DIPEA, 25 °C, 2–16 h.
  • HATU (1.1–1.3 eq) + DIPEA (2–3 eq) in anhydrous DMF or NMP, 0–25 °C, 1–6 h; efficient for hindered amines, minimizes urea byproducts.

• Activation alternatives:

  • Oxalyl chloride (1.2 eq) with catalytic DMF in DCM, 0–25 °C, 1–2 h → acid chloride; then couple to amine base (2–3 eq) at 0–5 °C to control exotherm.

• Purification:

  • Precipitation/trituration from MTBE/Et2O/hexanes; gel filtration (Sephadex LH‑20) or reverse‑phase chromatography for difficult mixtures; GPC for polymeric separations.

Yields depend on substrate and end‑group fidelity; PEGylated products often show 70–95% isolated yield for clean couplings under optimized conditions (literature ranges).

Safety & Handling

• Item-specific hazard data (from Product Data):

  • Signal word: Not specified for this item; refer to SDS.
  • H-statements: Not specified for this item; refer to SDS.
  • GHS classification/pictograms: Not specified for this item; refer to SDS.

• General safety considerations for PEG oligomers and tert‑butyl esters (informational):

  • Expected hazards: Typically low acute toxicity for PEG backbones; avoid inhalation of dust/aerosols and prolonged skin contact. Tert‑butyl esters are generally stable but can hydrolyze under strong acid, generating isobutylene; perform deprotection in a fume hood.
  • PPE: lab coat, nitrile gloves, safety glasses; use in a well‑ventilated hood, especially during acidolysis or solvent handling.
  • Incompatibilities: Strong acids will cleave the tert‑butyl ester (intended in deprotection protocols). Strong bases/alkoxides can promote transesterification of the ester end group. Oxidizers are generally compatible with saturated PEGs, but minimize exposure to strong oxidants and dehydrating agents.
  • Thermal handling: Avoid overheating; many PEG derivatives darken on prolonged heating. For drying, use mild vacuum at ≤40–45 °C unless literature procedure dictates otherwise.
  • First aid (overview; defer to SDS): On skin/eye contact, rinse with water for ≥15 minutes. If inhaled, move to fresh air. If ingested, rinse mouth; seek medical advice.

Always consult the product SDS for authoritative hazard, exposure limits, spill response, and disposal guidance.

Solvent Selection

m-PEG9-t-butyl ester is an amphiphilic oligomer with excellent solubility in many organic media.

• Item-specific solvent limits: Not specified for this item; refer to CoA/Spec Sheet.

• General/literature miscibility profile:

  • Good solvents: DCM, chloroform, THF, DMSO, DMF, NMP, acetonitrile, methanol, ethanol, isopropanol, ethyl acetate.
  • Limited/variable: Hexanes, heptane (solubility improves with co‑solvents due to the PEG chain’s polarity).
  • Aqueous systems: The tert‑butyl ester reduces water solubility relative to the free acid; water miscibility may be modest. After deprotection to the carboxylic acid or salt, aqueous solubility increases substantially.

• Selection guidance by application:

  • Ester deprotection: DCM or CH2Cl2:TFA mixtures; EtOAc/hexanes for triturations.
  • Couplings (post‑deprotection): DMF, DMSO, or NMP for carbodiimide or uronium chemistry; add base (DIPEA) as needed.
  • Film/formulation: THF or EtOAc enable uniform casting with hydrophobic polymers; DMSO/DMF suited for polar matrices.

• Comparison (general):

  • vs hydroxy‑PEG9: Hydroxy end is more reactive toward carbonate/urethane formation but lacks the latent acid handle.
  • vs PEG9‑acid: Acid is directly water‑soluble and coupling‑ready but less storage‑stable than the tert‑butyl ester.

Dry, oxygen‑free handling is typically not required, but low moisture improves weighing accuracy and reproducibility.

Storage & Reconstitution

• Item-specific instructions (from Product Data):

  • Storage: Store at −20 °C.
  • Shipping: Ice chest + ice pads.

• General handling recommendations for PEG oligomer esters (informational):

  • Keep container tightly closed under dry, inert atmosphere if possible; PEGs can absorb moisture which may affect mass and reactivity.
  • Allow vial to equilibrate to room temperature before opening to minimize moisture condensation; recap promptly after use.
  • If a solution is desired, prepare in anhydrous solvents (e.g., DCM, DMF, DMSO, THF) at typical stocking concentrations (50–200 mg/mL). Store solutions at −20 °C when compatible with solvent stability; minimize freeze–thaw cycles by aliquoting.
  • Avoid prolonged exposure to strong acids/bases during storage; perform deprotection immediately before use.

• Stability notes:

  • Tert‑butyl esters are generally stable under neutral conditions. Under acidic conditions they hydrolyze rapidly—store away from acids.

For any specific shelf‑life, water content limits, or impurity specifications, refer to the product’s CoA/Spec Sheet.

Structure & Identity

Brief description: m-PEG9-t-butyl ester is a monofunctional methoxy–poly(ethylene glycol) oligomer (average length n≈9 ethylene glycol units) bearing a tert‑butyl ester protecting group at the opposite terminus. This format provides a latent carboxylic acid that can be unveiled by acidolysis for subsequent coupling.

• Item-specific facts (from Product Data):

  • Product Name: m-PEG9-t-butyl ester (SKU: M596809)
  • Storage: Store at −20 °C
  • Shipped in: Ice chest + ice pads
  • Molecular formula: Not specified for this item; refer to CoA/Spec Sheet.
  • Molecular weight: Not specified for this item; refer to CoA/Spec Sheet.
  • CAS, InChIKey, SMILES: Not specified for this item; refer to CoA/Spec Sheet.

• Structural features (general/literature description):

  • One terminus: methoxy cap (–OCH3), rendering the PEG chain monofunctional.
  • Backbone: approximately 9 repeating –CH2–CH2–O– units (oligoethylene glycol).
  • Opposite terminus: tert‑butyl ester [–C(=O)–O–C(CH3)3] of a carboxylate linker. Under acidic conditions this deprotects to the corresponding carboxylic acid (m‑PEG9‑CO2H).
  • 2D description: linear polyether chain with terminal methyl ether on one end and a bulky tert‑butyl ester moiety on the other; no stereocenters; no rings; predominantly flexible, hydrogen‑bond accepting polyether.

Synthetic Utility

Functional design: m-PEG9-t-butyl ester is a monofunctional PEG bearing a latent carboxyl group. It serves as a modular spacer to introduce hydrophilicity and conformational flexibility while enabling robust downstream coupling chemistry.

• Key transformations (general/literature):

  • Deprotection: tBu ester → carboxylic acid via acidolysis (TFA, HCl/dioxane). The resulting m‑PEG9‑CO2H is a versatile synthon.
  • Amide formation: EDC/NHS or HATU/DIPEA coupling to primary/secondary amines on small molecules, polymers, surfaces, or biomolecules.
  • Activation: Conversion to acid chlorides (oxalyl chloride) or mixed anhydrides (isobutyl chloroformate) for less polar substrates; handle under dry conditions to avoid PEG backbone degradation.
  • Further derivatization: Formation of NHS esters (isolable or in situ), azides/alkynes via amide linkers for click strategies, or RAFT/ATRP initiators by coupling to 2‑bromoisobutyryl or dithiobenzoate handles.

• Retrosynthetic value:

  • Provides a defined, short PEG segment (n≈9) for tuning distance and solvation. Compared to longer PEGs, it balances hydrophilicity with minimal mass burden.

• Analytical:

  • Monitor by 1H NMR (PEG methylenes ~3.4–3.8 ppm; tBu singlet ~1.45 ppm), MALDI/ESI MS (broad isotope/envelope), GPC for Mn/Ð, and IR (ester C=O ~1735 cm−1; acid C=O shifts upon deprotection).

Target Specificity

This product is a small‑molecule/oligomeric reagent, not a biological affinity reagent. No antigen/epitope specificity, clone, isotype, or species reactivity applies.

• Item-specific data available: None provided; refer to CoA/Spec Sheet if any conjugation targets are listed for specific kit formats.

Frequently Asked Questions

What is the purity of this product?

This product is supplied at ≥98% purity (chemical assay). Lot-specific values are stated on the Certificate of Analysis.

How should this product be stored?

Store at ?20 °C. Freezer storage is required to maintain the specified shelf life.

How is this product shipped?

This product ships in an insulated container with ice pads. Unpack on arrival and transfer it to the storage condition stated above.

What documentation is provided?

Available product documentation, including Certificates of Analysis (COA), Safety Data Sheets (SDS), and specification sheets, is shown in the product document area. Document availability and access follow the current site policy.