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Chemical Synthesis

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The reagents and intermediates a route consumes rather than produces. Most are ordinary compounds bought repeatedly, which is exactly why the purchase turns on the lot rather than the molecule: a reagent that behaved one way in development and differently in the first production batch is the commonest cause of a route that will not reproduce.

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Listed on the TSS storefront and searchable there by name or CAS number. Every enquiry is contracted and invoiced by Taitil Global Inc. in the United States or Europe.

Specifying it

What decides the purchase

The compound is usually fixed by the route. These are the things that vary between suppliers and between lots.

  1. Specify purity against the next step, not against the catalogue

    A reagent consumed early and purified away by two subsequent steps rarely needs the highest grade offered. One entering late, or carrying an impurity that survives the workup, does. Decide which case you are in before paying for a grade the chemistry does not use — the cost difference between technical and AR on a bulk reagent is often several fold.

  2. Water is the impurity that is not on the certificate

    Many reagents are hygroscopic, and a Karl Fischer figure measured at manufacture says nothing about a drum that has been opened, part-used and resealed. For moisture-sensitive chemistry, state the water limit you need and ask whether it is re-tested at despatch rather than reported from the original batch record.

  3. Stabilisers and inhibitors come with the material

    Ethers carry BHT, chlorinated solvents carry amylene or methanol, and monomeric reagents carry polymerisation inhibitors. These are deliberate and usually harmless, but they appear in your reaction and occasionally in your product. Ask what the stabiliser is and at what level — an unstabilised grade exists for most of them, at a shorter shelf life.

  4. Lot-to-lot consistency is the thing you are really buying

    For a route being validated, the useful question is not what this lot assays at but how tightly the supplier holds the specification across lots. Ask for certificates from two or three recent batches and compare the impurity profiles rather than the headline assay. A supplier who cannot produce them is telling you something.

Questions

What is the difference between technical, AR and USP grade?
Technical grade has no compendial standard behind it and the specification is whatever the supplier states. AR (analytical reagent) is a purity grade with declared limits on named impurities, suitable for laboratory and most synthetic work. USP and the other pharmacopoeial grades certify against a published monograph with defined test methods, which is what a regulated product requires. Higher is not automatically better: pharmacopoeial grade on a reagent purified away three steps later adds cost without adding control.
Why does the same reagent behave differently between lots?
Usually water, a stabiliser at a different level, or a trace impurity that the assay does not resolve. A 99% assay leaves 1% unaccounted for, and the composition of that 1% is not constant between manufacturing campaigns. If a route is sensitive to it, specify limits on the specific impurities rather than relying on the assay figure alone.
Can you supply a reagent that is not in the catalogue?
Often, yes. The catalogue is what is listed, not the limit of what can be sourced — send the compound or CAS number and the quantity and we will come back on availability and lead time.