| HS Code | 736020 |
| Product Name | DL-Alanine Ethyl Ester Hydrochloride |
| Cas Number | 617-27-6 |
| Mdl Number | MFCD00044448 |
| Linear Formula | CH3CH(NH2)COOC2H5 · HCl |
| Molecular Formula | C5H11NO2 · HCl |
| Smiles | CCOC(=O)C(C)N.Cl |
| Appearance | White crystalline powder |
| Purity | 98% |
| Melting Point | 110-112°C |
| Solubility | Soluble in water, ethanol and methanol |
| Storage Conditions | Store in a cool, dry place, keep container tightly closed |
As an accredited DL-alanine Ethyl Ester Hydrochloride factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Supplied as 25 g in a sealed glass bottle, stored under inert gas and protected from moisture. |
| Container Loading (20′ FCL) | 20′ FCL loading of DL-alanine Ethyl Ester Hydrochloride: packed drums on pallets, securely braced, moisture-protected, container ventilated and sealed. |
| Shipping | Ship DL-alanine Ethyl Ester Hydrochloride at ambient temperature in a tightly sealed, moisture-proof container. It is not regulated as dangerous goods under standard transport rules. Protect from humidity and strong oxidizing agents. Use double polyethylene bags inside a sturdy fiberboard box or drum with clear chemical labeling. |
| Storage | Store DL-alanine ethyl ester hydrochloride in a tightly sealed container in a cool, dry, well-ventilated area, ideally at 2–8 °C. Protect from moisture, light, and contact with strong acids, bases, or oxidizing agents. Keep the container tightly closed when not in use and handle under inert gas if moisture-sensitive applications require it. |
| Shelf Life | Shelf life is typically 2 years when stored sealed in a cool, dry place, protected from moisture and light. |
Solution-phase coupling with DL-alanine ethyl ester hydrochloride begins with freebase generation in dichloromethane at 0–5°C by adding 1.05 eq N-methylmorpholine. The neutralised ester is combined with a preactivated Boc- or Fmoc-protected amino acid prepared from 1.10 eq DCC and 1.10 eq HOBt in the same solvent. Batch records from 50 L to 200 L glass-lined reactors establish that residual moisture above 0.5 wt% by Karl Fischer titration promotes DCC-derived N-acylurea side product; raw material acceptance for moisture-sensitive coupling campaigns therefore applies a Karl Fischer limit of ≤0.5 wt% according to Ph. Eur. 2.5.12.
The process stream is filtered through diatomaceous earth to remove N,N'-dicyclohexylurea, washed with cold 0.1 M HCl to remove tertiary amine, then washed with 5% w/v sodium bicarbonate. The organic phase is concentrated on a rotary evaporator at ≤35°C and ≤80 mbar. The terminal product, a C-terminal protected peptide ethyl ester, is isolated by column chromatography on silica gel 60 Å using ethyl acetate/hexane gradients. The ethyl ester is deliberately retained until final chain assembly to avoid premature carboxylate ionisation. The racemic configuration restricts this route to racemic peptide reference standards, impurity markers, and SAR probes; enantiopure API synthesis uses D- or L-alanine ethyl ester hydrochloride after stereochemical control is confirmed.
Biphasic N-acylation is conducted in water and ethyl acetate with 20% w/w aqueous sodium carbonate as acid scavenger. The hydrochloride is dissolved in water at 1.0 mol/L and cooled to 5–10°C before 1.05 eq benzoyl chloride or acetyl chloride is added dropwise over 45–60 min. A pH-stat maintains the aqueous phase between 7.5 and 8.5. Below pH 7.5 the acylation rate falls steeply; above pH 8.5, base-catalysed ethyl ester hydrolysis generates detectable alanine and ethanol within 30 min at 10°C.
After completing the addition, the batch is stirred for 2–3 h and separated through a plate-and-frame separator or centrifugal extractor. The ethyl acetate solution is washed with water until the aqueous conductivity is below 50 µS/cm, dried over anhydrous sodium sulfate, and concentrated under vacuum at ≤45°C to prevent thermal degradation of N-acyl derivatives. The product, N-acyl-DL-alanine ethyl ester, is obtained as a low-melting solid or oil and is used directly in reduction to N-acyl amino alcohols or hydrolysis to N-acyl alanine. Residual ethyl acetate is controlled to ≤5000 ppm under ICH Q3C(R8) Class 3, and residual dichloromethane is limited to ≤600 ppm when used as co-solvent.
The racemic hydrochloride is converted to the free-base acetate or phosphate and subjected to enantioselective ester hydrolysis in a stirred-tank reactor equipped with a pH-stat. A process-relevant enzyme for short-chain aliphatic amino acid esters is an immobilised Bacillus subtilisin preparation, EC 3.4.21.62, loaded at 1:100 to 1:500 w/w relative to substrate. Substrate concentration in potassium phosphate buffer is maintained between 50 mM and 200 mM, pH 7.0–8.2, temperature 20–35°C. Non-enzymatic base hydrolysis becomes significant above pH 8.2; below pH 7.0, subtilisin esterase activity declines sharply.
Automatic titration with 0.5 M NaOH holds pH at the setpoint while protons are released from the hydrolysing ester. The endpoint is determined when base uptake reaches 50% of the theoretical amount corresponding to the L-enantiomer, or by chiral HPLC determination of enantiomeric excess in the organic phase. Unreacted D-alanine ethyl ester is recovered by continuous extraction with ethyl acetate at 20–25°C. L-alanine remains in the aqueous phase and is concentrated under vacuum at ≤45°C, then crystallised by adjustment to the isoelectric point. The D-ester is re-salted with HCl gas in dry ethanol to obtain D-alanine ethyl ester hydrochloride.
Process conflict: the free-base ester must not be stripped under deep vacuum before acidification because alanine ethyl esters can self-condense to diketopiperazines. Published data for this specific DL-alanine ethyl ester hydrochloride under production-scale biphasic conditions is limited; the ranges above are derived from homologous short-chain amino acid ester resolutions and should be verified by laboratory-scale E-value screening.
| Route | Critical pH window | Temperature window | Key reagent / catalyst | Typical equipment | Terminal product |
|---|---|---|---|---|---|
| Solution-phase peptide coupling | Neutral after freebase generation | 0–5°C activation; 20–25°C coupling | DCC / HOBt | Glass-lined reactor, nutsche filter, rotary evaporator | C-terminal protected peptide ethyl ester |
| Schotten-Baumann N-acylation | 7.5–8.5 | 5–10°C addition | 20% w/w Na₂CO₃ | Jacketed pH-stat reactor, centrifugal separator | N-acyl-DL-alanine ethyl ester |
| Enzymatic kinetic resolution | 7.0–8.2 | 20–35°C | Immobilised Bacillus subtilisin | pH-stat stirred tank, extractor | D-alanine ethyl ester HCl / L-alanine |
| Ester reduction | N/A, anhydrous | 0–5°C | LiAlH₄ | Stainless steel reactor, anchor agitator, pressure filter | DL-2-aminopropan-1-ol |
Reduction of DL-alanine ethyl ester hydrochloride to DL-2-aminopropan-1-ol requires freebase formation and rigorous moisture control. The hydrochloride is suspended in tetrahydrofuran and treated with 1.05 eq triethylamine, then filtered. The solution is added dropwise to a slurry of lithium aluminium hydride in THF at 0–5°C under nitrogen in a stainless steel reactor with anchor agitator. Molar ratio of LiAlH₄ to ester is maintained at 1.0:1.0; excess reagent above 1.2 eq creates gelatinous aluminium hydroxide masses that slow filtration on a nutsche filter.
After stirring for 2–4 h, the batch is quenched sequentially with water, 15% w/w NaOH, and water at 0–5°C. The precipitated aluminium salts are filtered through a pressure filter with polypropylene cloth. The filtrate is acidified and extracted to remove THF; the aqueous amino alcohol is isolated by distillation under reduced pressure. Because the racemic configuration does not satisfy the stereochemical requirement of clinical oxazolidinone antibacterials, DL-alaninol output is directed to non-clinical scaffold synthesis, process impurity preparation, or racemic reference compounds. Enantiopure (S)-alaninol routes require chiral reduction or resolution before ester reduction.
Analytical-use shipments of DL-alanine ethyl ester hydrochloride are typically qualified as a racemic reference material for HPLC method development and impurity tracking. The salt is dissolved in mobile phase to 1.0 mg/mL and derivatised before injection with o-phthaldialdehyde and N-isobutyryl-L-cysteine in pH 9.0 borate buffer at 25°C for 2 min. The resulting diastereoisomers are separated on an octadecylsilyl silica column, 5 µm, 250 mm × 4.6 mm, using a phosphate buffer pH 7.2/acetonitrile gradient. Fluorescence detection at excitation 340 nm and emission 450 nm permits quantitation of 0.1% enantiomeric impurity. The racemic standard fixes the elution order and peak identity in methods validated according to ICH Q2(R1).
| Standard / Guideline | Test method / clause | Relevant control |
|---|---|---|
| ICH Q3C(R8) | Residual solvents | Dichloromethane ≤ 600 ppm; ethyl acetate ≤ 5000 ppm |
| ICH Q2(R1) | Analytical method validation | Specificity, linearity, accuracy, limit of quantification |
| USP 621 | Chromatographic system suitability | Resolution ≥ 1.5; tailing ≤ 2.0 |
| Ph. Eur. 2.2.46 | Chromatographic separation | Peak identification in racemic reference |
| ICH Q7 | API intermediate GMP | Batch records, change control, raw material acceptance |
Competitive DL-alanine Ethyl Ester Hydrochloride prices that fit your budget—flexible terms and customized quotes for every order.
For samples, pricing, or more information, please contact us at +8615365186327 or mail to admin@ascent-chem.com.
We will respond to you as soon as possible.
Tel: +8615365186327
Email: admin@ascent-chem.com
Flexible payment, competitive price, premium service - Inquire now!
DL-Alanine ethyl ester hydrochloride is identified by CAS Registry Number 617-27-6, molecular formula C5H11NO2·HCl, and relative molecular mass 153.61. Commercial supply commonly differentiates a technical grade with assay not lower than 96.0% by non-aqueous titration and a pharmaceutical intermediate grade with assay not lower than 98.0% by high-performance liquid chromatography or perchloric acid titration. Because the substance is a racemic crystalline salt, purchase specifications replace optical rotation with enantiomeric ratio by chiral HPLC where route selectivity requires verification. Typical certificate of analysis parameters include appearance, assay, water content by ASTM E203, residue on ignition by Ph. Eur. 2.4.14, chloride content by potentiometric titration, and residual solvents evaluated against ICH Q3C limits. Lot-to-lot variation is predominantly associated with residual ethyl acetate or ethanol from recrystallization and with moisture pickup in non-barrier packaging. The salt is soluble in water and lower alcohols; quantitative solubility data for the racemic salt under controlled crystallization conditions is limited and should be obtained from the supplier before solvent-volume calculations are fixed.
Industrial suppliers also classify the material into standard, dried, and micronized grades. Dried grade is specified for water-sensitive coupling reactions, while micronized grade is specified for continuous solid feeding. Selection of a lot release profile therefore depends on the downstream unit operation and not solely on chemical purity. The theoretical chloride content, calculated as atomic chlorine divided by formula weight, is 23.1%; a specification window of 22.5–23.5% accounts for residual moisture and free hydrogen chloride variation.
In carbodiimide-mediated coupling, the protonated amino group has negligible nucleophilicity; therefore, one molar equivalent of a tertiary amine, typically N,N-diisopropylethylamine or N-methylmorpholine, is added to liberate the free amino ester. Premature addition of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide to a neutralized suspension at pH above 10 accelerates ester hydrolysis, and the liberated ethyl alaninate can undergo diketopiperazine formation if local base concentration is uncontrolled. In jacketed reactors with Pt100 temperature probes, the neutralization exotherm is controlled below 5 °C before coupling agent addition. Residual water above 0.2% in the reaction solvent consumes carbodiimide and reduces coupling efficiency; Karl Fischer titration by ASTM E203 is used for solvent release. Process samples are monitored by HPLC with UV detection at 210 nm. Published kinetic data for this specific racemic hydrochloride under aqueous coupling conditions is limited; pre-campaign lab verification with spiked starting material is required before scale-up beyond pilot scale.
In solution-phase peptide synthesis, the product functions as a carboxyl-protected alanine donor. The hydrochloride form is preferred over the free amino ester because the solid salt is mechanically easier to charge at kilogram scale and does not evolve volatile amine vapour during routine handling. The free base is generated in situ rather than isolated. When the material is used with active esters, such as pentafluorophenyl esters or 1-hydroxybenzotriazole-activated carboxylic acids, tertiary amine loading is adjusted to compensate for both the ester hydrochloride and the acidic coupling partner. The racemic nature of the DL product excludes it from homochiral peptide active pharmaceutical ingredient routes where a single alanine enantiomer is required; in those routes, L-alanine ethyl ester hydrochloride is selected and released against specific rotation and enantiomeric purity by chiral HPLC. The DL product is accordingly directed toward achiral alanine derivatives and racemic process development, where chiral purity is not the critical quality attribute.
The racemate differs from the L and D enantiomer salts by the absence of optical rotation and by its process fit in achiral synthesis. L-Alanine ethyl ester hydrochloride is the standard enantiopure form for homochiral peptide coupling and is controlled for specific rotation and enantiomeric purity. D-Alanine ethyl ester hydrochloride is used for peptidomimetic scaffolds and bacterial cell wall precursor studies. β-Alanine ethyl ester hydrochloride is a positional isomer with the amino group at the β-carbon; it does not behave as an interchangeable α-amino acid ester and has different acid-base and coupling behaviour. Selection criteria are summarised in the matrix below.
| Product form | Isomerism | Chiral purity control | Main process fit |
|---|---|---|---|
| DL-Alanine ethyl ester hydrochloride | Racemic mixture of D and L | Not controlled by polarimetry; enantiomeric ratio by chiral HPLC if required | Achiral routes, racemic process development, cost-sensitive intermediates |
| L-Alanine ethyl ester hydrochloride | L enantiomer | Specific rotation and chiral HPLC | Homochiral peptide synthesis |
| D-Alanine ethyl ester hydrochloride | D enantiomer | Specific rotation and chiral HPLC | Peptidomimetic scaffolds, cell wall research |
| β-Alanine ethyl ester hydrochloride | β-position isomer | Not applicable | β-Amino acid derivatives, poly-β-alanine precursors |
Compared with the methyl ester hydrochloride, the ethyl ester reduces the rate of acid-catalyzed hydrolysis of the carboxyl-protecting group and provides a more favourable boiling-point differential for solvent recovery. In process development, the ethyl ester is selected when the final deprotection step uses saponification in aqueous ethanol; the methyl ester may be selected when faster deprotection is acceptable. The choice between DL-alanine ethyl ester hydrochloride and the L enantiomer depends on whether the target molecule is homochiral; the racemate is not a drop-in substitute in chiral routes.
The hydrochloride salt is stored under inert gas at 2–8 °C in low-density polyethylene liners inside fibre drums. If ambient relative humidity exceeds 60%, the material is pre-dried under vacuum at 40 °C for not less than 4 h before charging to moisture-sensitive reactions. Aqueous processing at pH above 10 should be limited to not more than 30 min at 0–5 °C because ester hydrolysis becomes competitive; this boundary is derived from general amino acid ester stability data rather than a product-specific formal stability study. Process developers should replace water-miscible solvents with dichloromethane or ethyl acetate for free-base extraction after neutralization. At pH above 9, phase splits in large-scale extraction can become slow; addition of sodium chloride or use of a disc-stack centrifuge at 2000 g relative centrifugal force reduces rag-layer build-up. The temperature coefficient of hydrolysis for low-molecular-weight amino acid esters is consistent with an apparent activation energy in the range 40–60 kJ mol-1 in neutral-to-alkaline solution; published values specific to this racemic hydrochloride are limited. Compatibility boundaries include avoidance of prolonged contact with strong bases above pH 10, aqueous ammonia, primary amines in hot alcoholic solution, and concentrated mineral acids below pH 2. Strong oxidising agents are excluded because the free amine and ester are oxidisable.
On production-scale agitated filter dryers, the crystalline powder shows variable flow after storage at 25 °C. Batches with residual ethyl acetate above 0.3% form soft agglomerates under vacuum filtration; wet-cake compression at 0.2 bar nitrogen pressure reduces throughput if the recrystallization solvent is not displaced by n-heptane. Equipment with polished 316L stainless steel contact surfaces and polytetrafluoroethylene filter cloth has been used to limit product adhesion. Under bulk discharge, electrostatic charging is observed when relative humidity is below 30%; nitrogen ionisation bars and conductive hoppers are required on such lines. Batch-to-batch variability in particle-size distribution arises from recrystallization cooling rate and stirring speed in the final crystallizer. If the D90 exceeds 150 µm, conveying and micronization become more difficult. These handling constraints are not related to product purity but to particle-size distribution and residual solvent, both of which alter the powder rheology during conveying and vacuum drying.
For pharmaceutical intermediate supply, release testing is harmonised with ICH Q3C and ICH Q3D. Acceptance limits are supplier- and route-dependent and must be aligned with downstream process capability and with the intended regulatory starting material status under ICH Q7. A representative specification matrix is shown below; values are typical for pharmaceutical intermediate grade and are not a universal release specification.
| Parameter | Acceptance criterion | Method |
|---|---|---|
| Appearance | White to off-white crystalline powder | Visual inspection |
| Assay | ≥ 98.0% | HPLC external standard or non-aqueous titration |
| Water content | ≤ 0.5% | ASTM E203 |
| Chloride as HCl | 22.5–23.5% | Potentiometric titration or ion chromatography |
| Residue on ignition | ≤ 0.1% | Ph. Eur. 2.4.14 |
| Residual solvents, ethyl acetate and ethanol | ≤ 5000 ppm each | Headspace gas chromatography, ICH Q3C class 3 |
| Elemental impurities | Per ICH Q3D, route-dependent | Inductively coupled plasma mass spectrometry |
| Storage and re-evaluation | 2–8 °C, dry, inert gas; 12 months from release | Sealed container, barrier packaging |
Material retained beyond the assigned re-evaluation interval should be re-tested for water content, assay, and residual solvents before use in regulated intermediate campaigns. If the package has been opened under relative humidity above 60%, drying under vacuum at 40 °C is applied and water content must be verified before charge.
