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Anhydrous Solvents
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High Purity
Scharlau Anhydrous Solvents
Scharlau anhydrous solvents are engineered to meet the demanding requirements of laboratories performing moisture-sensitive chemical reactions. These solvents undergo a multi-step purification process in reactors ranging from 300 Lto 5000 L, involving high-efficiency vacuum distillation and chemical treatments to eliminate trace impurities. The resulting products exhibit extremely low water content, often measured as low as 10 ppm to 30 ppm, which is critical for the success of reactions such as Grignard synthesis, oligonucleotide production, and combinatorial chemistry.
To preserve this high degree of dryness, Scharlab utilizes a sophisticated packaging system that includes specialized amber glass bottles and an innovative septum-sealing technology. Each bottle is conditioned prior to filling to remove any residual moisture from the glass surface and then filled under a dry nitrogen atmosphere. For added protection, the bottles are vacuum-sealed in non-permeable aluminum bags, guaranteeing a shelf life of up to three years.
Precision Moisture Quantification via Karl Fischer Titration
The cornerstone of anhydrous solvent quality is the rigorous quantification of residual water. Scharlab employs coulometric Karl Fischer titration to verify that moisture levels remain within the defined ppm limits. This electrochemical method provides the high sensitivity required to detect trace amounts of H2O that would otherwise interfere with catalytic or organometallic processes. Each batch is accompanied by a certificate of analysis detailing the actual water content measured, ensuring transparency and reliability for the end-user.
Multi-Layer Septum and PTFE Sealing Technology
To enable repeated access to the solvent without contamination, a specialized multi-layer septum cap is utilized. This closure features a PTFE/elastomer/PTFE sandwich structure. The inert PTFE layers protect the solvent from contact with the elastomer and prevent the migration of plastic phthalates, while the inner elastomer layer provides self-sealing properties. When a syringe needle is withdrawn, the elastomer effectively closes the puncture site, maintaining a tight seal against the external environment.
Inert Gas Atmosphere and Vacuum Processing
Maintaining an anhydrous state requires a completely controlled environment during the manufacturing process. The solvents are distilled and transferred under an inert nitrogen gas blanket to prevent the absorption of atmospheric O2 and H2O. This inert gas processing extends from the initial purification in large-scale reactors to the final bottling stage, ensuring that the solvent never comes into contact with ambient air before it reaches the laboratory.
Molecular Sieves for In-Situ Drying and Maintenance
Certain grades of anhydrous solvents are supplied with molecular sieves directly integrated into the bottle. These crystalline aluminosilicates act as a drying agent, actively trapping any moisture traces that might enter the container during use or through repeated piercings of the septum. By utilizing 3A or 4A sieves, the system ensures that the solvent remains within the specified ppm range, typically below 50ppm, even after multiple openings in a laboratory setting.
Advanced Purification and Vacuum Distillation
The manufacturing of anhydrous solvents involves sophisticated distillation columns designed to achieve high separation efficiency. High-purity starting materials are subjected to vacuum distillation to lower the boiling point and minimize thermal degradation of the solvent. This process effectively removes non-volatile residues and cross-contaminants, resulting in an assay (purity) that typically exceeds 99.9\%. The removal of alkali metals and other ionic impurities further enhances the suitability of these solvents for electronic and mass spectrometry applications.
Microfiltration and Particle Control Standards
Beyond chemical purity, physical cleanliness is vital for modern analytical techniques.This process removes sub-micron particulates that could clog HPLC columns or interfere with sensitive mass spectrometry (LC-MS) signals. Controlling the particle count ensures batch-to-batch consistency and protects the integrity of delicate laboratory instrumentation.
Applications in Sensitive Organometallic Synthesis
The use of anhydrous solvents is indispensable in organometallic chemistry, where reagents like Grignard compounds or alkyl-lithiums react violently with water. The presence of H2O leads to the exothermic decomposition of these reagents, resulting in poor yields or hazardous conditions. Scharlau solvents provide the necessary "dry" environment for these syntheses, as well as for peptide and oligonucleotide production, where moisture can prevent the formation of critical covalent bonds in the polymer chain.
Protective Aluminum Vacuum Packaging and Shelf Life
To provide a long-term barrier against moisture ingress, the primary glass containers are vacuum-packed in specialized aluminum bags. These bags are non-permeable to water vapor and provide a secondary layer of protection during shipping and storage. This over-packaging is a technical safeguard that guarantees the product will retain its specified anhydrous quality for up to three years from the date of manufacture, provided the vacuum seal remains intact.
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