Chlorosulfonyl Isocyanate (CSI)

Name: Chlorosulfonyl Isocyanate (CSI)
Brand: Royalchem
Rating: 5.0 (47 reviews)

Model: Industrial Grade ≥99.0%
Brand: Royalchem
Code: 1189-71-5

Product Description

Product Name	Chlorosulfonyl Isocyanate (CSI) (Synonyms: N-Carbonylsulfamyl Chloride; Sulfuryl Chloride Isocyanate; N-(Oxomethylidene)sulfamoyl Chloride)
CAS NO.	1189-71-5
Formula & Molecular Weight	CClNO₃S (Linear Formula: ClSO₂NCO) \| MW: 141.53 \| EC: 214-715-2
Chemical Structure
Product Type	Reactive Synthetic Reagent / LiFSI Precursor / Pharmaceutical Intermediate Chlorosulfonyl Isocyanate contains both chlorosulfonyl and isocyanate groups. This combination makes CSI useful in carbamoylation, sulfonylation, addition, substitution and cyclization reactions.
Typical Specification	Appearance: Clear, colorless to pale yellow liquid Assay (GC): ≥99.0%
Reference Properties	Physical State: Liquid at 20°C Boiling Point: Approx. 106–108°C Density: Approx. 1.63 g/mL at 20°C Refractive Index: Approx. 1.445–1.449 at 20°C Moisture Sensitivity: Highly moisture sensitive Water Reactivity: Reacts violently and decomposes on contact with water, potentially releasing corrosive or toxic gases Reference-property values are provided for product identification and process evaluation only. They are not fixed Royalchem batch-release specifications.
Key Applications	CSI is a highly reactive bifunctional reagent used in LiFSI precursor production, pharmaceutical carbamoylation and advanced fine-chemical synthesis. LiFSI Precursor Route: CSI can react with chlorosulfonic acid to produce bis(chlorosulfonyl)imide (HCSI). HCSI is subsequently fluorinated to bis(fluorosulfonyl)imide (HFSI) and then lithiated to produce LiFSI. Cefuroxime Synthesis: Used as a carbamoylation reagent in selected cefuroxime processes to introduce the carbamoyloxymethyl functionality. Cefoxitin and Beta-Lactam Chemistry: Used in selected cefoxitin and other beta-lactam synthesis routes, including specific carbamoylation and ring-forming transformations. Carbamoylation and Sulfonylation: Used to introduce carbamoyl or sulfonyl functionality into suitable pharmaceutical, agrochemical and specialty-chemical intermediates. Fine-Chemical Process Development: Applied in addition, substitution and cyclization reactions for preparation of nitrogen- and sulfur-containing intermediates.
Packaging, Storage & Shipping	Packaging: Stainless-steel drums or other compatible special packaging may be provided according to product grade, quantity and dangerous-goods requirements. Final package material and net weight are confirmed with the commercial order. Storage: Keep strictly dry and protect from heat and moisture. Store in tightly closed, compatible containers in a cool, dry and well-ventilated area under suitable inert gas. A storage range of 2–8°C may be used where specified by the applicable supplier TDS or SDS. Shipping: IMDG, IATA and ADR documents commonly classify CSI as UN3265, Class 8, Packing Group II. U.S. DOT documentation may classify it as UN3129, Class 4.3 with subsidiary Class 8, Packing Group II. Final shipping classification is subject to the actual SDS, route, carrier acceptance and destination-country regulations.

Sourcing Chlorosulfonyl Isocyanate for LiFSI or Cephalosporin Synthesis?

Royalchem supplies Chlorosulfonyl Isocyanate (CSI, CAS 1189-71-5) for bis(chlorosulfonyl)imide and LiFSI precursor routes, cephalosporin carbamoylation and other advanced fine-chemical synthesis applications.

Batch-specific COA, SDS, specification confirmation and route-specific logistics support are available for commercial inquiries. Please provide the target application, assay and impurity requirements, quantity, package requirements and destination country.

Role of CSI in the LiFSI Production Route

Step 1: HCSI Production	Chlorosulfonyl Isocyanate reacts with chlorosulfonic acid to produce bis(chlorosulfonyl)imide, commonly abbreviated as HCSI.
Step 2: Fluorination	HCSI is converted through a suitable fluorination process into bis(fluorosulfonyl)imide, commonly abbreviated as HFSI.
Step 3: Lithiation	HFSI is reacted with a suitable lithium-containing compound to produce lithium bis(fluorosulfonyl)imide (LiFSI).
Quality Considerations	Purity, moisture and metal-ion control at the CSI and HCSI stages can affect water, free-acid, metal and other critical impurity levels in downstream LiFSI. Customers should provide process-specific quality requirements with the inquiry.

Pharmaceutical and Synthetic Roles of CSI

Cefuroxime	CSI is used as a carbamoylation reagent in selected cefuroxime routes to construct the carbamoyloxymethyl functionality.
Cefoxitin	CSI is used in selected cefoxitin processes for carbamoylation of the corresponding cephalosporin intermediate.
Beta-Lactam and Heterocycle Synthesis	CSI can participate in selected addition and cyclization reactions used to construct beta-lactam and other nitrogen-containing ring systems.
Sulfonylation and Carbamoylation	Its chlorosulfonyl and isocyanate functionalities make CSI useful for introducing sulfonyl and carbamoyl groups into suitable organic intermediates.

Frequently Asked Questions

What is CAS 1189-71-5?	CAS 1189-71-5 is Chlorosulfonyl Isocyanate, commonly abbreviated as CSI. Its molecular formula is CClNO₃S.
Does CSI directly produce LiFSI?	Not in a single direct step. CSI is first used to prepare bis(chlorosulfonyl)imide, which is then fluorinated and lithiated through subsequent process stages to produce LiFSI.
How is CSI used in cephalosporin synthesis?	CSI acts mainly as a carbamoylation reagent in selected cefuroxime, cefoxitin and related cephalosporin synthesis routes.
Why must CSI be protected from moisture?	CSI reacts violently and decomposes on contact with water, potentially releasing corrosive or toxic gases. Storage, sampling and processing must therefore follow the applicable SDS and dry-handling requirements.
Why can the CSI shipping classification differ?	Different regulations may classify CSI according to its corrosive or water-reactive hazards. IMDG, IATA and ADR documents commonly use UN3265, while U.S. DOT documentation may use UN3129. The actual batch SDS and route-specific carrier review control the shipment.
Can Royalchem provide COA and SDS?	Batch-specific COA, SDS and specification information can be provided. Please include the target application, assay and impurity requirements, quantity, packaging and destination country with the inquiry.

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