1-Bromo-5-chloropentane Pharma Grade API for Tablet / Capsule / Granule / Injection, Oral & Injectable is specified as a pharmaceutical intermediate for active pharmaceutical ingredient synthesis rather than as a directly compressible, encapsulated, or injectable drug substance. The product, CAS 54512-75-3, molecular formula C5H10BrCl, molecular weight 185.49 g/mol, is a liquid halogenated compound in which the terminal bromine and chlorine sites provide sequential reactivity for constructing drug molecules before final dosage-form development. In tablet, capsule, and granule manufacturing, the material is consumed in upstream synthesis of the final API; it does not enter the final blend, wet granulation, capsule fill, or tablet matrix. In injectable processing, the free halide is not lyophilized or filled into vials; it is converted into a purified, isolated drug substance that later meets injectable monograph requirements. Published direct oral or parenteral administration data for the unreacted compound are limited.

How Does Terminal Bromide Versus Terminal Chloride Alter SN2 Selectivity in Route Design?

The five-carbon spacer places a bromine at C1 and a chlorine at C5, creating two electrophilic termini with distinguishable leaving-group reactivity. In polar aprotic solvents such as dimethylformamide, dimethyl sulfoxide, or acetonitrile, the terminal bromide undergoes SN2 displacement more rapidly than the terminal chloride. This difference is exploited to introduce a protected amine, thiol, or carboxylate at the bromide terminus while retaining the chloride for a later heterocycle alkylation or chain extension. Relative reactivity follows the standard halogen leaving-group order in SN2 chemistry, with bromide more labile than chloride; published kinetic data for this exact substrate in commercial reactors are limited. Compared with 1,5-dibromopentane, the hetero-dihalide reduces the probability of bis-substituted by-products because the second chloride site is less active under mild conditions. Compared with 1,5-dichloropentane, the presence of the bromide lowers the activation energy for the first displacement and allows shorter reaction times or lower temperatures. The difference does not eliminate side reactions: elimination to pentenyl chloride isomers can occur if strong base is added too rapidly, if the reaction temperature exceeds the qualified setpoint, or if the amine nucleophile is insufficiently soluble. Process development therefore fixes stoichiometry, addition rate, and internal temperature within narrow limits. The reaction mass is typically maintained under nitrogen, and the vessel is equipped with a jacket capable of removing the exotherm from the first displacement step.

For oral solid dosage development, the downstream drug substance—not 1-bromo-5-chloropentane—is the component that enters formulation. Tablet development uses the final API for compatibility studies with microcrystalline cellulose, lactose monohydrate, croscarmellose sodium, colloidal silicon dioxide, and magnesium stearate under ICH Q1A conditions. Granulation may be performed in a high-shear mixer with impeller tip speed of 5 m/s to 10 m/s and a granulation end-point controlled by power consumption or torque rather than by fixed time. Drying in a fluid-bed dryer with inlet air temperature of 60 °C to 70 °C must be qualified for the final API’s thermal sensitivity. Capsule filling may use a dosator or tamping-pin machine with fill weight variability below ±3% relative standard deviation. These unit operations are applicable only after the bromo-chloro intermediate has been chemically consumed, the final drug substance has been isolated, and residual starting material has been controlled below the permitted limit. For a molecule such as 1-bromo-5-chloropentane that may be considered a potential alkylating impurity, the residual level in the final oral API should be derived from ICH M7 toxicological assessment or a default threshold of toxicological concern of 1.5 µg/day unless otherwise justified.

When Injectable Routes Are Considered, Endotoxin and Particulate Control Precede Final Fill-Finish

Injectable development does not use the free bromo-chloro compound as a formulation component. The intermediate is converted into a final drug substance that is subsequently crystallized, converted to a pharmaceutically acceptable salt if required, and purified to reduce residual starting material, related substances, and elemental impurities. The sterile liquid or lyophilized product is tested for bacterial endotoxin per USP <85>, sterility per USP <71>, particulate matter per USP <788>, and residual solvents per USP <467>. The final injectable API must meet the stringent elemental impurity limits of ICH Q3D through the parenteral route, which requires lower daily exposure values than many oral products. Residual 1-bromo-5-chloropentane in the final injectable drug substance is controlled by a validated liquid chromatography–mass spectrometry or gas chromatography–mass spectrometry method. The free halide is not a sterile API, has no endotoxin release specification, and is not included in finished injectable monographs as an active ingredient or excipient. The pharma grade classification therefore supports upstream chemical synthesis, not direct parenteral administration.

The commercial product is supplied as a clear, colorless to pale-yellow liquid. Because it is a liquid at ambient temperature, the product has no tablet-grade particle-size distribution, bulk density, or compressibility specification. Model designations in distribution documents often appear as BR-C5-Cl-PG or equivalent; these are supplier-specific and should be verified against the certificate of analysis. Packaging may include 500 g, 1 kg, and 5 kg amber borosilicate glass bottles, with larger quantities in 25 kg fluorinated high-density polyethylene drums. Storage is typically at 2 °C to 8 °C under inert gas, protected from light, with limited headspace moisture. Repeated sampling from a single container should be minimized because moisture ingress promotes hydrolysis of the terminal bromide to 5-chloropentan-1-ol. The material is incompatible with strong bases, strong oxidizing agents, and reactive metal surfaces; glass-lined or passivated stainless steel equipment with fluoropolymer gaskets is recommended for process-scale handling.

Release Specification, Documentation, and Container-Closure Architecture

A pharma grade lot differs from technical grade primarily in the controlled release specification and the quality system surrounding the lot. The certificate of analysis should include identity, assay, water, residual solvents, elemental impurities, and residue on ignition. A typical release specification may include assay by GC-FID not less than 98.0% area, water by Karl Fischer not more than 0.10%, total impurities not more than 2.0%, single impurity not more than 0.5%, and residual solvents per USP <467> and ICH Q3C. Elemental impurities are controlled per USP <232>/<233> and ICH Q3D. Documentation includes the batch record, packaging statement, and change control under ICH Q7. For injectable-track synthesis, the receiving unit may also request bioburden or endotoxin data on the incoming intermediate if the downstream process does not have a later destruction or removal step.

Process-scale handling of 1-bromo-5-chloropentane is dominated by the need to exclude moisture and control the first exothermic displacement. In a 500 L glass-lined reactor equipped with a retreat-curve impeller operating at 80 rpm to 120 rpm, the bromide-bearing substrate is typically added slowly to a solution of the nucleophile and a suitable acid acceptor. The jacket temperature is held at 0 °C to 10 °C during the addition; if the internal temperature exceeds the upper setpoint, the addition is stopped and the reaction is recirculated through an external heat exchanger or the jacket is switched to chilled brine. The vessel is blanketed with nitrogen at a slight positive pressure of 0.02 bar to 0.05 bar. When phase-transfer catalysis is needed, tetrabutylammonium bromide or a similar quaternary ammonium salt is used at 0.5 mol% to 2 mol%. Published batch-to-batch variance data in public equipment bulletins for this exact substrate are limited, so the qualified operating range must be established during process characterization on the intended manufacturing line. After the reaction, the organic phase is washed with water or dilute brine, dried over magnesium sulfate or molecular sieves, and concentrated under reduced pressure at a bath temperature not exceeding 40 °C to minimize distillation losses.

Direct Dosage-Form Use Is Not Supported by Pharmacopoeial Monographs or Toxicological Data

The designation “pharma grade” should not be interpreted as a finished pharmaceutical or direct active ingredient for tablet, capsule, granule, injection, oral, or injectable administration. 1-Bromo-5-chloropentane functions as a starting material or intermediate for API synthesis under ICH Q7. Current pharmacopoeial monographs, including USP and Ph. Eur., do not list the unreacted compound as an active pharmaceutical ingredient for direct oral or parenteral use. A formulation scientist should not add the liquid intermediate to a final blend, granulating solvent, capsule fill, or sterile solution. If the compound is present in the final drug substance, it is treated as a residual starting material or potential mutagenic impurity under ICH M7 and controlled to a justified limit. The relevant product differences are therefore: technical grade is suitable for non-pharmaceutical synthesis; pharma grade is suitable for controlled API manufacture; and only the isolated, purified downstream drug substance is suitable for finished tablet, capsule, granule, or injectable product.

Cleaning validation for equipment exposed to 1-bromo-5-chloropentane requires an analytical method capable of detecting residual halide at the equipment surface. Swab or rinse samples are collected from the reactor manway, baffle, agitator, and discharge valve after a campaign. The acceptance limit is derived from the maximum allowable carryover of the intermediate into the next product, often based on the threshold of toxicological concern of 1.5 µg/day divided by the maximum daily dose of the next API. Solvent rinses such as dichloromethane or acetonitrile are suitable only if subsequent drying and residual solvent checks are performed per USP <467>. Product-contact elastomers should be replaced or dedicated because halogenated liquids can swell natural rubber and some silicone gaskets. These cleaning and containment controls complete the route-specific quality boundary.