(2S)-1,1-Dimethyl-2,3,4,5-Tetrahydropyrrole-2-Carboxylate

Pre-treatment of lignocellulosic biomass with deep eutectic solvents (DES) formulated from (2S)-1,1-dimethylpyrrolidinium-2-carboxylate eliminates the need for aggressive inorganic acids and permits operation at atmospheric pressure. This inner salt—a quaternary ammonium carboxylate—acts as a hydrogen-bond acceptor, paired with glycerol, ethylene glycol, or 1,2-propanediol at molar ratios of 1:2 to 1:4. The preparation is carried out in a glass-lined stirred vessel heated to 80–100 °C under nitrogen blanket until a homogeneous, transparent liquid is obtained, typically within 45–90 min. Residual water must be held below 1.0 wt%, determined by Karl Fischer titration per ASTM E203, as values above 2.0 wt% cause a marked drop in lignin solubilization efficiency and raise the dynamic viscosity above 800 mPa·s at 40 °C, which impedes transfer through centrifugal pumps with 1.0 hp motors commonly installed in biorefinery pilot plants. After cooling to 50 °C, the DES is charged into a jacketed percolation column packed with hammer-milled corn stover or wheat straw at 10–15 wt% solids loading; residence times of 3–6 h at 120 °C achieve 65–80% delignification, monitoring absorbance at 280 nm in the spent liquor. The cellulose-rich pulp, washed with acetone-water (1:1 v/v) and dried to <5 % moisture, shows an enzymatic digestibility improvement of 40–60% versus untreated substrate when assayed with Cellic CTec3 at 15 FPU/g glucan. Viscosity stability at shear rates up to 100 s⁻¹ is measured on a Brookfield DV2T viscometer with cone-plate geometry (CPE-40); no shear thinning is observed within the 20–60 °C range. The DES is recovered by nanofiltration on a ceramic membrane (0.2 µm), concentrated in a wiped-film evaporator at 60 °C and 50 mbar, and re-used for up to 5 cycles with <3% loss of delignification performance. Carbon steel (AISI 1045) impellers in prolonged contact exhibit corrosion rates below 0.02 mm/year, though pitting is noted after 800 h of continuous operation; switching to 316L stainless steel eliminates the pitting risk entirely. The downstream cellulose is suitable for fermentation into bioethanol or conversion into dissolving pulp.

What operational pH range ensures baseline enantioseparation in capillary electrophoresis using proline betaine as the chiral selector?

Resolution of basic drug enantiomers in capillary electrophoresis (CE) with (2S)-1,1-dimethylpyrrolidinium-2-carboxylate relies on a carefully bounded pH window where the analyte ionization and the selector’s zwitterionic state coexist. Background electrolyte (BGE) is prepared by dissolving the compound at 10–30 mM in 50 mM sodium phosphate buffer, adjusted with 1.0 M H₃PO₄ or NaOH to a pH of 2.5–4.0. Below pH 2.2, the carboxylate group of the selector becomes protonated, converting it into a cation and destroying the electrostatic pocket required for chiral discrimination; above pH 4.5, the selector’s net charge shifts, and electroosmotic flow (EOF) accelerates, collapsing the migration time window. For the separation of β-blockers—e.g., atenolol, metoprolol—the optimal condition is pH 3.0 with 20 mM selector and 10% v/v methanol to suppress EOF and reduce Joule heating. A fused-silica capillary (50 μm I.D., 50 cm total length, 41.5 cm effective length) is preconditioned under 20 psi with 0.1 M NaOH for 10 min, followed by water and BGE each for 5 min. Injection is performed hydrodynamically at 0.5 psi for 5 s, and a separation voltage of +20 kV is applied; UV detection at 214 nm via a Beckman P/ACE MDQ system captures peak areas. Under these conditions, resolution (Rs) for metoprolol enantiomers exceeds 2.0, with efficiency surpassing 250,000 plates/m for the second eluting peak. Method validation per USP 〈726〉 requires assessment of repeatability (RSD ≤2.0% for migration time, ≤5.0% for corrected area), limit of detection below 0.5 µg/mL, and linearity range 5–200 µg/mL (R² > 0.999). Capillary temperature must be strictly held at 25±0.5 °C, as fluctuations of ±1 °C alter migration times by 2–3% due to viscosity shifts. The selectivity is lost when adding more than 15% v/v acetonitrile because the selector precipitates at the cathode interface. Fresh BGE must be replenished after every 6 runs to prevent ion depletion; electrolyte drift profiles monitored through current logs show a 12% conductance drop by the tenth run without replacement. This method is deployed in pharmaceutical quality control for enantiomeric purity testing of bulk actives, where the terminal output is a certificate of analysis stating enantiomeric excess (ee >99.5%).

Feed-grade hepatoprotective premix: stability data and dosing protocol for monogastric species

Inclusion of (2S)-1,1-dimethylpyrrolidinium-2-carboxylate—commonly referred to as stachydrine—in complete feed for pigs and poultry targets hepatic lipid metabolism and has been adopted in least-cost formulation matrices at concentrations of 200–800 mg/kg feed as a botanical-derived inner salt. The feed additive is first blended into a lignocellulose-based carrier (rice husk powder, 60–100 mesh) to form a 2% or 5% premix using a twin-shaft paddle mixer (WLDH-0.5 model) operating at 25 rpm for 5 min, with a coefficient of variation (CV) target of ≤5% according to ISO 8466-2. Before pelleting at 75–85 °C with a conditioning time of 30–45 s, the premix is subjected to simulated steam exposure in a lab-scale conditioner (Muench Edelstahl) to confirm recovery; losses are kept below 5%, as verified by cation-exchange HPLC with refractive index detection at 40 °C. Stability testing in a climate chamber at 40 °C/75% RH for 90 days shows 97.8% retention of the active compound, whereas the presence of choline chloride above 500 mg/kg in the premix induces hygroscopic bridging that reduces flowability to FBD<4 mm (Flodex test) and accelerates degradation by 8%; formulators are advised to segregate choline chloride addition or use a 1:1 blend with silica gel (DS-10) to maintain powder flow. The premix is dosed into a horizontal ribbon mixer of 1000 L capacity together with maize-soybean meal base, targeting a final mash homogeneity of 90±5% recovery at 10 sampling points. Compliance falls under EU Regulation (EC) No 1831/2003 for feed additives; the product is registered as a technological-feed additive under the functional group “substances which favourably affect the quality of animal products,” though national registrations differ. The terminal finished feed formulation is labeled for growing-finishing pigs and broilers, carrying guaranteed minimum stachydrine content of 100 mg/kg as-fed. Hepatic triglyceride reduction of 15–22% relative to controls after 42-day trials in Cobb 500 broilers was recorded, with the biological data referenced in internal dossiers submitted to the EFSA FEEDAP panel.

An uninterrupted methyl-donor pathway is posited as one mechanism, though no authorized health claims appear on the label beyond the compositional guarantee. Monitoring of peroxide value in the premix is mandated every 30 days; values exceeding 5 meq O₂/kg trigger antioxidant supplementation with 200 ppm ethoxyquin or rosemary extract.

Manufacturing of (2S)-1,1-dimethylpyrrolidinium-2-carboxylate intended as an active pharmaceutical ingredient (API) starting material proceeds from synthetic or plant-extracted crude material through recrystallization in absolute ethanol-water (95:5 v/v) under ICH Q7 certified Good Manufacturing Practice. The crystalline white powder is isolated on a pressure nutsche filter (0.5 m²) washed with chilled ethanol at 0–5 °C, and dried in a double-cone rotary vacuum dryer at 40 °C and ≤10 mbar until loss on drying is ≤0.5%. Particle size reduction is conducted on a jet mill (Fluid Energy Aljet) with compressed nitrogen at 6 bar to achieve a volume median diameter Dv50 of <50 µm as measured by laser diffraction on a Malvern Mastersizer 3000 with Aero S dry dispersion unit. The micronized material is tested against specifications for residual solvents (ethanol ≤2000 ppm, methanol ≤1000 ppm) via headspace GC-FID in accordance with USP 〈467〉, heavy metals (≤10 ppm, Ph. Eur. 2.4.8), and enantiomeric purity (≥99.0% e.e. by chiral HPLC on a Chirobiotic T column). Identity is confirmed by IR spectrum matching USP reference standard, specific optical rotation [α]_D²⁰ of -108° to -112° (c=1.0, H₂O, 20 °C), and a melting endotherm at 235–238 °C recorded by differential scanning calorimetry at 10 °C/min (ISO 11357-1). The product is intended for direct compression into hepatoprotective tablets (label claim 100 mg) blended with microcrystalline cellulose, croscarmellose sodium, and magnesium stearate in a V-blender; tablet hardness of 50–70 N and disintegration time <15 min (USP 〈701〉) define the terminal dosage form. Validation batches manufactured in 300 kg lots under Class D cleanrooms consistently deliver assay values of 98.5–101.0%. Incompatibilities are noted with reducing sugars during wet granulation, where the inner salt undergoes a Maillard-like browning reaction at >60 °C outlet air temperature, requiring direct compression as the preferred solid dosage route.

Field trials of (2S)-1,1-dimethylpyrrolidinium-2-carboxylate as a plant biostimulant demonstrate its osmoprotective role when applied as a foliar spray at concentrations of 50–200 mg/L on tomato (Solanum lycopersicum) and cucumber (Cucumis sativus) under saline irrigation (4–8 dS/m electrical conductivity). The spraying solution is prepared by dissolving the inner salt in deionized water, adding a non-ionic surfactant (alkyl polyglycoside, 0.05% v/v) to enhance leaf wetting, and adjusting pH to 5.5–6.5 with citric acid. Application is performed using a backpack sprayer delivering 300 L/ha at early bloom and fruit set; leaf gas exchange measured with a portable photosynthesis system (LI-6800) at 48 h post-application shows stomatal conductance improved by 12–18% and chlorophyll fluorescence (Fv/Fm ratio) maintained above 0.78 compared to 0.71 in untreated controls. The material is not classified as a pesticide; its marketing in the EU falls under Regulation (EU) 2019/1009 as a non-microbial biostimulant, requiring batch-level certification of amino acid content and heavy metals below 0.5 mg/kg Cd and 10 mg/kg Pb. The terminal product to growers is a water-soluble concentrate (SL formulation) containing 100 g/L active ingredient, packaged in 1 L HDPE bottles. Shelf life of 24 months at 5–30 °C is supported by accelerated stability data at 54 °C. Tank-mix incompatibility occurs with copper-based fungicides, where complexation precipitates the inner salt; a jar test is mandatory before large-scale mixing.