Vinyl sulphone ester is the common trade name for 4-(beta-sulphatoethylsulphonyl)aniline, often called para base ester or PBE. It is the intermediate that gives vinyl sulphone reactive dyes their reactive group. To buy it well, specify the assay and method, moisture and impurity limits, and plan for dry storage.
Many buyers search for the vinyl sulphone price. This article gives no price. It covers what to specify and what decides what a supplier will quote.
Specify the assay and how it is measured
The key figure is the content of the main compound. For an aromatic amine like this, assay is usually run by diazotisation titration or by HPLC. Write the method into the specification, because different methods can give different numbers on the same lot.
State whether the percentage refers to dry material. Our guide on intermediate purity and HPLC versus titration explains the options.
Other points for the specification
- Moisture content, since the material can take up water and lose assay during storage.
- Appearance and colour, as a darker lot can point to impurities or ageing.
- Insoluble matter and, if relevant to your process, the level of inorganic salts.
- Related compounds such as isomers and unreacted starting materials. See impurities in intermediates.
- The pH of a solution at a stated concentration.
Storage and handling
Keep vinyl sulphone ester dry, sealed and away from heat and strong alkali. Ask for the storage conditions and shelf life on the supplier's technical data sheet, and follow the safety data sheet for handling. Check the SDS for hazard classification and for the transport classification of your grade, because it decides the packaging and freight route. Read whether dye intermediates are hazardous cargo before you book.
Where it is used
The ester becomes the reactive group on dyes that bond to cotton and other cellulosic fibres. Reactive Black 5 is a well-known example. For the dye side, see vinyl sulphone dyes.
What decides the price
A supplier's quote moves with these factors:
- The cost of the aromatic raw materials and the sulphonating and esterifying chemicals used in the synthesis.
- The assay and impurity limits you demand, which affect yield and purification work.
- Effluent treatment, since this chemistry produces waste that must be handled legally.
- Order size, pack and delivery terms.
- General market demand from reactive dye makers. See why intermediate prices change.
Checking a lot on arrival
Test the assay on arrival with the method written in the specification, and compare it with the certificate of analysis. Check the moisture and the appearance, and keep a sealed retention sample from every lot.
The final test is the dye you make from it. If your yield or shade changes after a new lot, compare the intermediate with a retained sample of a good lot before you blame the process. Our guide on intermediate purchase complaints lists common problems and how to raise them.
Next step
Send the same specification to several makers, ask for a sample from current production and test it before you order. We find and audit intermediate plants, check samples and documents, and have lots tested. For a real quote, book a free sourcing review.