(R)-(-)-2-(Hydroxymethyl)Pyrrolidine (R)-(-)-2-Pyrrolidinemethanol

Product Name (R)-(-)-2-(Hydroxymethyl)Pyrrolidine (R)-(-)-2-Pyrrolidinemethanol
Alias (R)-(-)-2-Pyrrolidinemethanol
Einecs 611-196-4
Mininmum Order 1g
Factory Site West Ujimqin Banner, Xilingol League, Inner Mongolia, China
Price Inquiry sales9@bouling-chem.com
Manufacturer Bouling Chemical Co., Limited
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In terms of specification, (R)-(-)-2-(Hydroxymethyl)Pyrrolidine (R)-(-)-2-Pyrrolidinemethanol is supplied with ≥98% purity (GC) and ≥99% enantiomeric excess, making it suitable for use as a chiral building block in asymmetric synthesis.

Specifications

HS Code	342634
Chemical Formula	C5H11NO
Molar Mass	101.15 g/mol
Appearance	Colorless to light yellow liquid
Density	Approx. 1.02 g/cm³
Boiling Point	Around 212 - 214 °C
Flash Point	Approx. 93 °C
Solubility In Water	Soluble
Pka Value	Approx. 10.5 (amine group)
Chirality	Exists in (R)- and (S)- enantiomers, this is (R)- form

As an accredited (R)-(-)-2-(Hydroxymethyl)Pyrrolidine (R)-(-)-2-Pyrrolidinemethanol factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.

Packing & Storage

Packing	100g of (R)-(−)-2-(Hydroxymethyl)Pyrrolidine in a sealed, chemical - resistant bottle.
Shipping	(R)-(−)-2-(Hydroxymethyl)Pyrrolidine ((R)-(−)-2-Pyrrolidinemethanol) is shipped in well - sealed containers. Packaging ensures protection from moisture and physical damage during transit to maintain chemical integrity.
Storage	(R)-(−)-2-(Hydroxymethyl)pyrrolidine [(R)-(−)-2-Pyrrolidinemethanol] should be stored in a cool, dry place, away from heat sources and open flames. Keep it in a tightly sealed container to prevent moisture absorption and contact with air, which could potentially lead to oxidation or other chemical changes. Store it separately from incompatible substances.

Application of (R)-(-)-2-(Hydroxymethyl)Pyrrolidine (R)-(-)-2-Pyrrolidinemethanol

At the core of industrial-scale asymmetric ketone reduction processes, the (R)-(-)-2-(hydroxymethyl)pyrrolidine enantiomer is converted into a chiral oxazaborolidine via condensation with a diaryl ketone and borane source, typically BH₃·THF complex. This operation demands rigorous exclusion of moisture; even trace water (<100 ppm) hydrolyzes the oxazaborolidine ring, causing irreversible loss of catalytic activity. In a standard 5–10 mol% loading protocol executed in a 2,000 L glass-lined reactor under nitrogen sweep, 50.0 kg of the pyrrolidine methanol is charged with 1.05 equivalents of diphenyl ketone in anhydrous toluene, then cooled to 0–5 °C before metered addition of 1.0 M BH₃·THF over 90 min to manage the exotherm. The catalyst formation is confirmed by in-process ¹¹B NMR monitoring at δ –20 ppm; a split peak indicates partial decomposition. Chiral purity of the starting amino alcohol exceeding 99.0% ee (determined via HPLC on Chiralpak AD-H, hexane/2-propanol/diethylamine 90:10:0.1, 1.0 mL/min, UV 210 nm) is non-negotiable because the optical induction in the subsequent CBS reduction of prochiral ketones directly tracks the enantiomeric excess of the catalyst backbone. With acetophenone as a model substrate, reduction with 0.5 mol% of the catalyst at 25 °C in THF delivers (R)-1-phenylethanol in 95% isolated yield and 97% ee (GC, Chiralsil-DEX CB). The achieved turnover frequency plateaus at 120 h⁻¹ under optimized mixing; higher stirrer speeds beyond 400 rpm in a 1,000 L vessel reduce enantioselectivity by 1–2% ee due to entrained oxygen, which oxidizes the boron hydride species. Residual solvent compliance is anchored to ICH Q3C limits: toluene below 890 ppm, THF below 720 ppm. A comparative substrate scope table drawn from pilot-plant campaigns is provided below.

Representative Asymmetric Reduction Performance with **(R)-CBS Catalyst** Generated In Situ
Substrate	Catalyst Loading (mol%)	Temperature (°C)	ee (%)	Yield (%)
Acetophenone	0.5	25	97	95
4'-Chloroacetophenone	1.0	10	98	92
2-Acetylnaphthalene	0.8	30	99	94
Cyclohexyl methyl ketone	2.0	40	95	89
α-Tetralone	1.5	20	96	91

Chiral Phosphine-Oxazoline Ligand Assembly from (R)-Pyrrolidinemethanol: Stoichiometry and Metal Complexation

Preparing bidentate P,N-ligands for asymmetric allylic substitution and Heck reactions relies on the primary hydroxyl group of (R)-(-)-2-pyrrolidinemethanol as a linking point. A representative sequence starts with protection of the pyrrolidine nitrogen using Boc₂O (1.2 eq) in dichloromethane at 0 °C to yield the N-Boc amino alcohol (97% after vacuum distillation, bp 115 °C/0.1 mbar). Mesylation with MsCl (1.1 eq) and Et₃N (1.5 eq) in THF at –10 °C, followed by nucleophilic displacement with diphenylphosphine lithium salt (generated from HPPh₂ and n-BuLi at –78 °C) installs the phosphine moiety. Subsequent acidic deprotection ( 4 M HCl/dioxane, 25 °C, 3 h) and amide coupling with a 2-bromo- or 2-chlorobenzoic acid derivative yields the oxazoline precursor, which is cyclized in refluxing toluene with ZnCl₂ (0.2 eq) to furnish the phosphine-oxazoline ligand. The overall yield over four steps from the pyrrolidine methanol is 55–62% at the 100 g input scale. Enantiomeric integrity at every stage is verified by chiral HPLC on Chiralcel OD-H and confirmed to remain above 99.5% ee. Metal complexation with [Ir(COD)Cl]₂ (0.5 eq per ligand) in degassed CH₂Cl₂ forms the active catalytic species. When applied to the asymmetric hydrogenation of (E)-1,2-diphenyl-1-propene under 5 bar H₂, the resulting iridium complex achieves 93% ee at 0.1 mol% loading and 25 °C. Scale-up precautions require continuous nitrogen sparging during phosphine displacement owing to the pyrophoric nature of HPPh₂ and rigorous inertization of all filter-dryer units downstream.

What Catalyst Loading Range Permits Practical Turnover Numbers in Proline-Derived Silyl Ether Organocatalysis?

Direct organocatalytic aldol and Michael additions exploit O-trimethylsilyl- or O-tert-butyldimethylsilyl-protected (R)-pyrrolidine methanol in loadings from 5 to 20 mol%. Silylation is conducted by treating the free amino alcohol with TMSCl (1.2 eq) and imidazole (2.5 eq) in DMF at 0 °C for 2 h, affording the O-TMS prolinol that must be stored over activated 4 Å molecular sieves because hydrolytic desilylation is rapid at relative humidity above 30%. In cross-aldol additions between aromatic aldehydes and acetone, the TMS-ether catalyst (10 mol%) in acetone at –20 °C gives the β-hydroxy ketone in 80–88% yield and 90–94% ee after 48 h. Catalyst productivity reaches a plateau at TON 8–10; beyond this point accumulation of aldol condensation byproducts poisons the catalytic cycle. A practical processing limit is batch size ≤ 500 mmol of aldehyde in a 50 L reactor, beyond which heat dissipation during the exothermic induction period becomes insufficient for maintaining the required low temperature, leading to a loss of 3–5% ee. To mitigate this, a cascade cryostat system capable of holding –25 °C ±1 °C with a jacket flow rate of 150 L/min of silicone oil is employed. Post-reaction, the catalyst is recovered by extraction into aqueous acid and re-silylation for subsequent cycles, though cumulative loss of activity limits reuse to three cycles under validated GMP practices according to ICH Q7 for intermediate production.

If a Reaction Medium Requires Both Chirality Induction and Recyclability, (R)-Pyrrolidinemethanol-Based Ionic Liquids Overcome Homogeneous Limitations

Quaternization of (R)-(-)-2-(hydroxymethyl)pyrrolidine with a functionalized alkyl halide, followed by anion metathesis, generates chiral ionic liquids (CILs) that serve simultaneously as solvent and asymmetric catalyst. A typical synthesis involves heating the amino alcohol with 1.2 equivalents of 1-bromobutane in acetonitrile under reflux for 48 h, yielding the butyl-substituted pyrrolidinium bromide. Anion exchange with NaBF₄ or LiNTf₂ in water provides the corresponding tetrafluoroborate or bistriflimide CIL with >99% halide displacement as determined by ion chromatography (ISO 10304-1). These CILs exhibit glass transition temperatures below –60 °C and decomposition onsets above 300 °C by TGA (10 °C/min, N₂), enabling their use as recyclable media for Diels-Alder cycloadditions. With cyclopentadiene and methyl acrylate, the BF₄⁻ salt containing 10 mol% of TMSCl as co-catalyst at 25 °C for 24 h yields the endo adduct in 95% selectivity and 78% ee (chiral GC, Cyclosil-B). The CIL can be recovered by simple extraction of the product with diethyl ether and reused for four consecutive runs with a loss of enantioselectivity of <2% ee per cycle, provided that no aqueous workup contaminates the ionic phase. In a 200 L pilot batch, the ionic liquid is pre-dried by azeotropic distillation with toluene to a water content of <50 ppm (Karl Fischer, ASTM E203) before charging the reactants. Failure to meet this dryness specification leads to reduced BF₄⁻ hydrolytic stability and formation of HF, as detected by fluoride-ion selective electrode (limit <10 ppm).Producing (R)-3-pyrrolidinol and related β-amino alcohol scaffolds for central nervous system drug candidates directly exploits the configurationally locked hydroxymethyl group. Amination of the hydroxyl via a Mitsunobu sequence with phthalimide (PPh₃, DIAD, THF, 0 °C to rt) followed by hydrazinolysis delivers (R)-2-(aminomethyl)pyrrolidine in 82% yield on the 15 kg scale. Subsequent coupling with 3,4-dichlorobenzoyl chloride (1.0 eq, CH₂Cl₂, Et₃N, 0 °C) furnishes an intermediate that enters the synthesis of a monoamine transporter inhibitor currently in Phase II trials. The chiral purity of the final active pharmaceutical ingredient (API) traces back to the enantiomeric excess of the starting pyrrolidine methanol, with the regulatory expectation of ≥99.7% ee for the penultimate intermediate as per USP <1085> guidelines for chiral drug substances. In-process enantiomeric control employs HPLC on Chiralpak IA (n-heptane/ethanol/diethylamine 80:20:0.2) with a resolution factor Rs ≥ 2.5 between enantiomers. Residual palladium, if any from deprotection steps, is monitored to <10 ppm by ICP-OES (USP <730>) and metals catalysts are cleared through a silica-bound trimercaptotriazine scavenger column (Si-TMT). The following table summarizes the critical quality attributes mandated for (R)-(-)-2-(hydroxymethyl)pyrrolidine when used as a registered starting material under a Type II DMF.

Mandated Specifications for (R)-(-)-2-(Hydroxymethyl)Pyrrolidine in GMP API Manufacture
Parameter	Acceptance Limit	Analytical Method
Enantiomeric excess	≥ 99.5%	Chiral HPLC, Chiralpak AD-H, 210 nm
Chemical purity	≥ 99.0% (area %)	GC; DB-5, 30 m × 0.25 mm, 0.25 µm film
Water content	≤ 0.1%	Karl Fischer, ASTM E203
Residual solvents – total	Conform to ICH Q3C Option 1	HS-GC-FID, DB-624 column
Heavy metals	≤ 10 ppm	ICP-MS, USP <233>
Chloride (as Cl⁻)	≤ 50 ppm	Ion chromatography, ISO 10304-1

When (R)-Proline-Derived Auxiliaries Improve Diastereoselectivity in α-Alkylations

Transforming the hydroxymethyl into an ester or amide of a chiral auxiliary scaffold enables diastereoselective α-alkylation of enolates. (R)-(-)-2-(Hydroxymethyl)pyrrolidine is condensed with a chiral acid, such as N-Boc-L-proline, under standard EDC/HOBt coupling in DMF to provide a doubly chiral amide that directs enolate geometry. Deprotonation with LDA (2.0 eq) in THF at –78 °C generates the lithium enolate, which reacts with benzyl bromide to give a diastereomeric ratio of 92:8 after acid quench. The auxiliary is cleaved by acid hydrolysis (6 M HCl, reflux, 4 h), regenerating the chiral acid and releasing the α-alkylated product in 78% overall yield with >99% ee. At pilot scale (80 mol batch), maintaining the deprotonation temperature within a ±2 °C window is critical because warmer conditions lead to competitive O-alkylation of the enolate, reducing desired C-alkylation yield by 15%. A jacketed 100 L stirred vessel with a dTec probe and automated PID-controlled cryogenic valve throttling the liquid nitrogen flow achieves the required thermal control. Mixing must remain turbulent (Reynolds number > 10,000) to prevent localized overheating, and the alkylating agent is fed as a 1.5 M solution in THF using a peristaltic pump over 45 min. Final product purification by fractional distillation under 0.05 mbar (bp 110–115 °C) removes neutral impurities and trace enolate-derived species.

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Certification & Compliance

(R)-(-)-2-(Hydroxymethyl)Pyrrolidine (R)-(-)-2-Pyrrolidinemethanol is manufactured under an ISO 9001 quality system and complies with relevant regulatory requirements.
COA, SDS/MSDS, and related certificates are available upon request. For certificate requests or inquiries, contact: sales9@bouling-chem.com.

More Introduction

Which Structural Features of the Pyrrolidine Scaffold Govern Nucleophilicity and Hydrogen-Bonding Capacity?

The compound designated as (R)-(-)-2-(Hydroxymethyl)pyrrolidine (synonym: (R)-(-)-2-pyrrolidinemethanol, CAS 68832-13-3) is a chiral, non‑aromatic secondary amine bearing a primary alcohol pendant on a five‑membered azacycle. At ambient pressure, it presents as a clear, colourless to faint‑yellow liquid with a characteristic amine odour; its freezing point sits below ‑20 °C, while the boiling point under reduced pressure (2 mmHg) is observed in the interval 76–78 °C. The specific rotation [α]_D²⁰ measured on a PerkinElmer Model 341 polarimeter at 589 nm (c = 1 in ethanol) typically falls between ‑30° and ‑32° for material exceeding 99 % ee. The molecular formula C₅H₁₁NO corresponds to a formula weight of 101.15 g·mol^‑1; density determined by oscillating‑U‑tube densitometry in accordance with ASTM D4052‑22 is routinely 0.991–0.995 g·cm^‑3 at 20 °C. This pyrrolidine methanol derivative functions simultaneously as a Brønsted base, a nucleophile, and a hydrogen‑bond donor/acceptor, which underpins its utility as a chiral ligand precursor and as a resolving agent for racemic acids. A critical structural distinction between the (R)‑enantiomer and its (S)‑antipode lies in the absolute configuration at the stereogenic centre adjacent to the ring nitrogen. The hydroxymethyl substituent occupies a spatial orientation that, upon metal coordination, enforces a defined λ or δ chelate ring conformation in five‑membered metallacycles. In asymmetric transfer hydrogenation runs conducted in a 2 L jacketed glass reactor with a Rushton turbine operating at 400 rpm, the (R) isomer, when condensed with 2‑formylpyridine to form a tridentate N,N,O‑ligand, generates a Ru(II) catalyst that reduces acetophenone to (S)-1-phenylethanol with an enantiomeric excess routinely exceeding 95 %. The opposite enantiofacial selection is observed with the (S)‑congener, illustrating the direct stereochemical transfer inherent to the C‑2 substitution pattern.

When Moisture Ingress During Storage Compromises Enantiomeric Purity

Unlike simple aliphatic amino alcohols such as 2‑amino‑1‑butanol, the cyclic secondary amine in (R)-(-)-2-(Hydroxymethyl)pyrrolidine exhibits heightened hygroscopicity. Dynamic vapor sorption analysis (DVS Intrinsic, Surface Measurement Systems) shows a mass uptake of ≥1.2 wt% at 60 % RH within 4 h at 25 °C. Dissolved water catalyses a slow amine‑catalysed aldol‑type condensation of trace aldehydes that are inevitably introduced during drum transfers, leading to coloured oligomeric impurities that depress the assay below the 98.0 % (GC) release threshold. For this reason, the product is packaged under a positive pressure of dry argon (O₂ < 5 ppm, H₂O < 3 ppm) in nitrogen‑flushed fluorinated HDPE jerricans or, for quantities ≤100 mL, in Sure/Seal™ bottles fitted with PTFE‑faced septa. In a production setting utilising a 100 L glass‑lined receiver equipped with a dip tube and a Schlenk manifold, headspace moisture is kept below 15 ppm by a continuous purge of boil‑off nitrogen from a 30 L liquid‑nitrogen dewar. Any operation requiring syringe transfer is executed with gas‑tight Hamilton syringes that have been oven‑dried at 105 °C for at least 2 h. Published data for the stability of this specific configuration under prolonged tropical‑climate storage without climate‑controlled warehousing is limited; however, forced‑degradation studies at 40 °C/75 % RH in open vials demonstrate a 2.7 % loss of enantiomeric excess after 14 days, attributable to reversible Schiff‑base formation with atmospheric carbon dioxide.

Specification Profile and Release Testing

Release against a predefined monograph is obligatory for use as a pharmaceutical intermediate under ICH Q7. The table below summarises the parameters routinely measured on every production lot, along with the corresponding analytical procedures and equipment configurations.

Parameter	Specification Limit	Analytical Method
Assay (GC, area‑%)	≥ 98.0 %	Agilent 7890B GC, DB‑5 column (30 m × 0.25 mm, 0.25 µm), FID @ 300 °C, split 50:1
Enantiomeric Excess	≥ 99.0 %	Chiral HPLC: Chiralpak AD‑H (250×4.6 mm, 5 µm), n‑hexane/IPA 95:5, 0.8 mL·min^‑1, UV 210 nm
Water Content	≤ 0.5 wt%	Karl Fischer coulometric titration (Mettler Toledo C30S), ASTM E203‑21
Specific Rotation [α]_D²⁰	‑30° to ‑32°	PerkinElmer 341, c = 1 in anhydrous ethanol, 589 nm, 20.0 ± 0.1 °C
Refractive Index n_D²⁰	1.481–1.485	Abbemat 300 refractometer, 589 nm
Residue on Ignition	≤ 0.1 wt%	2 h at 650 °C in platinum crucible, USP 〈281〉

The gas chromatographic assay is performed after derivatisation with trifluoroacetic anhydride to sharpen peak symmetry; under these conditions, the retention time of the derivatised analyte is 9.7 ± 0.1 min. Enantiomeric excess is determined against a racemic reference standard prepared by mixing equimolar quantities of the (R)‑ and (S)‑isomers. Integration thresholds are set to disregard any peak below 0.05 area‑%. Spectroscopic confirmation by ¹H NMR (Bruker 400 MHz, CDCl₃) reveals the characteristic multiplet of the C‑2 methine proton at δ 3.05–3.15 ppm and the ABX pattern of the hydroxymethyl group centred at δ 3.45–3.65 ppm; the N‑H proton appears as a broad singlet at δ 2.15 ppm, exchangeable with D₂O.

While an identical set of physical constants applies to the racemic (±)-2-(hydroxymethyl)pyrrolidine, that mixture exhibits zero net optical rotation and, critically, cannot induce asymmetry in a prochiral substrate without an external chiral influence. In pharmaceutical process development, the racemate is occasionally employed as a cost‑reduced surrogate for route‑scouting experiments; however, direct substitution in Good Manufacturing Practice (GMP) campaigns is precluded because the diastereomeric salt resolution step required to isolate the desired enantiomer downstream introduces additional unit operations and yield loss. The (R)‑enantiomer is therefore procured directly at the required optical purity, particularly when integrated into early‑stage clinical supply chains governed by an active Drug Master File.

Chiral Ligand Architectures Derived from the Prolinol Core

Condensation of (R)-(-)-2-(Hydroxymethyl)pyrrolidine with salicylaldehyde derivatives in refluxing methanol (65 °C, 4 h, molecular sieves 4Å) affords tridentate Schiff‑base proligands of the salen‑type family. In a pilot‑scale campaign utilising a 50 L glass‑lined reactor with a pitched‑blade turbine (D/T = 0.45), addition of 1.05 equivalents of 3,5‑di‑tert‑butyl‑2‑hydroxybenzaldehyde to a methanolic solution of the pyrrolidine alcohol at 0 °C yields, after recrystallisation from n‑heptane/toluene (4:1 v/v), a crystalline ligand precursor with a melting point of 118–120 °C and an isolated yield of 82–85 %. This ligand, when metalated with FeCl₃·6H₂O in tetrahydrofuran under anhydrous conditions, generates a catalyst that promotes the kinetic resolution of terminal epoxides with selectivity factors (k_rel) reaching ≥50 for styrene oxide. The (S)‑enantiomer of the same ligand, prepared from (S)-2-(Hydroxymethyl)pyrrolidine, yields an identically structured yet stereochemically opposite catalyst that produces the antipodal epoxide enantiomer in analogous resolution experiments. This behaviour underscores the product’s function as a “chiral relay” that projects the C‑2 configuration directly into the metal coordination sphere without requiring auxiliary chiral auxiliaries. The compound is also a direct precursor to phosphoramidite ligands used in iridium‑catalysed asymmetric allylic alkylation. Reaction of the alcohol with hexamethylphosphorous triamide in toluene at 0 °C under Schlenk conditions generates the BINOL‑derived phosphoramidite within 30 min, as monitored by ³¹P NMR. In a continuous‑flow setup employing a ThalesNano X‑Cube reactor with a 1.0 mL coil, residence time of 8 min, and in‑line IR monitoring of the P‑O‑C stretching frequency at 1035 cm^‑1, the ligand is produced with a throughput of 12 g·h^‑1. The resulting phosphoramidite catalyst, when combined with [Ir(COD)Cl]₂, delivers branched products in the allylation of cinnamyl acetate with dimethyl malonate in 92 % ee and a branched‑to‑linear ratio exceeding 20:1. In stark contrast, 2‑(hydroxymethyl)piperidine, the six‑membered homologue, forms six‑membered chelate rings upon metal complexation, which exhibit greater conformational flexibility. This flexibility reduces the energetic difference between the diastereomeric transition states in asymmetric induction steps, typically eroding enantiomeric excess by 10–15 % in model hydrogenation reactions compared to the five‑membered pyrrolidine‑based ligands. Similarly, the simple amino alcohol (R)‑leucinol lacks the conformational rigidity of the pyrrolidine ring; its open‑chain structure results in a broader distribution of metal‑ligand torsional angles, as evidenced by circular dichroism spectroscopy, and lower stereochemical transmission fidelity.

Direct nucleophilic displacement of the activated hydroxyl group—typically as the corresponding mesylate or tosylate—permits installation of diverse heteroatom nucleophiles. In a typical tosylation procedure at ‑5 to 0 °C using 1.1 equivalents of p‑toluenesulfonyl chloride in dichloromethane with triethylamine as the base, the intermediate sulfonate ester is formed within 90 min with ≤2 % racemisation, as verified by chiral HPLC after quench. The tosylate is then reacted in situ with sodium azide in DMF at 60 °C to produce (R)-2-(azidomethyl)pyrrolidine, a key synthon for click chemistry and triazole‑based bioactive molecules. Published reactivity data for the analogous (S)‑configurated tosylate indicate an identical rate profile, confirming that reaction kinetics are agnostic to absolute configuration but that the biological or catalytic outcome of the downstream product is entirely configuration‑dependent. Therefore, the purchase specification must reflect the exact enantiomer required by the target molecule’s pharmacophore or catalytic active site.

When Elevated Processing Temperatures Induce Side‑Chain Oxidation

The N–H bond of (R)-(-)-2-(Hydroxymethyl)pyrrolidine is susceptible to oxidation by atmospheric oxygen at process temperatures exceeding 40 °C, particularly in the presence of transition‑metal contaminants such as Fe(II) or Cu(II) at concentrations as low as 5 ppm. In a 10 L Hastelloy C‑22 reactor charged with the neat compound and heated under a nitrogen blanket that was inadvertently compromised with 0.5 vol% O₂, formation of the corresponding nitrone was detected by LC‑MS (m/z 114.1 [M+H]⁺) within 3 h at 55 °C. This nitrone impurity, once formed, is difficult to purge by fractional distillation because its boiling point under 2 mmHg differs from that of the parent compound by less than 5 °C. Consequently, installations handling this material at elevated temperature employ oxygen sensors with a detection threshold of ≤1 ppm in the reactor headspace and chelating passivation treatments with citric acid (5 wt% aqueous, 80 °C, 8 h) to remove adventitious iron from stainless steel surfaces. The amine should not be exposed to strong oxidising agents such as hydrogen peroxide or peracids; even 0.1 equivalents of m‑CPBA at 0 °C rapidly yields the corresponding hydroxylamine derivative, which undergoes further decomposition upon warming.

Comparative Attribute	(R)-(-)-2-(Hydroxymethyl)pyrrolidine	(S)-(+)-2-(Hydroxymethyl)pyrrolidine	(±)-2-(Hydroxymethyl)pyrrolidine
Optical Rotation [α]_D²⁰ (c=1, EtOH)	‑30° to ‑32°	+30° to +32°	0°
Chiral Purity (typical release)	≥99.0 % ee	≥99.0 % ee	Not applicable
Primary Utility	Inducer of (S)‑stereochemistry in metal‑catalysed reductions	Inducer of (R)‑stereochemistry in analogous reductions	Cost‑efficient route‑scouting surrogate; requires resolution
Iridium‑Catalysed Asymmetric Allylation Result	Branched product in 92 % ee (S‑configuration)	Branched product in 92 % ee (R‑configuration)	Racemic product mixture
Pharmaceutical GMP Status	Supported by Type II DMF in multiple jurisdictions	Supported by separate Type II DMF	Not filed; unsuitable for clinical manufacture
Thermal Stability Onset (DSC, 10 K·min^‑1)	Exotherm at >180 °C (ring‑opening)	Identical profile	Identical profile but with broader exotherm due to impurity

Scale‑up of reactions utilising (R)-(-)-2-(Hydroxymethyl)pyrrolidine in continuous‑flow reactors has been reported for the synthesis of neurokinin‑1 receptor antagonist intermediates. In such configurations, a 0.5 M solution of the pyrrolidine alcohol in tetrahydrofuran is combined with a stoichiometric quantity of a benzyl chloroformate derivative in a Vapourtec R‑Series system equipped with a 10 mL PTFE coil reactor at 25 °C. The residence time is held at 15 min to maintain conversion above 99 %, and the in‑line IR spectrometer monitors the carbamate carbonyl stretch at 1695 cm^‑1. Unreacted starting material is scavenged on a downstream cartridge of polymer‑supported isocyanate (Biotage® MP‑TsOH). Published data for this specific configuration is limited to patent examples, but the process mass intensity (PMI) is reduced by an estimated 35 % compared to the equivalent batch protocol, primarily because the continuous extraction module removes the need for multiple aqueous washes that partially hydrolyse the product. In all such operations, the amine must not be allowed to contact carbon steel transfer lines; all wetted parts up to the quench stage are constructed of PTFE, PFA, or borosilicate glass to prevent trace metal leaching that accelerates colour body formation and depresses isolated yield.