UV Absorber Intermediate 2-Chlorobenzaldehyde CAS 89-98-5 Benzotriazole Synthesis Liquid

Benzotriazole UV absorbers, the workhorse stabilisers for engineering plastics and coatings, are assembled from an ortho substituted aromatic aldehyde and an azo coupling step before cyclisation. 2-Chlorobenzaldehyde (CAS 89-98-5) supplies both the ortho chlorine that is later displaced by an amine or phenol and the aldehyde carbon that becomes part of the triazole ring, so its purity directly determines the yield of the cyclisation stage.

This grade is distilled to 99.0 percent minimum with a tight isomer limit, because the 3- and 4-chloro isomers condense at different rates and produce triazoles that do not absorb in the required UV window, which shows up as a lower extinction coefficient in the finished stabiliser. Nitrogen blanketing in the drum protects the aldehyde from the oxidation that would otherwise add free acid load to the cyclisation step.

• Assay 99.0% minimum: higher yield in the cyclisation stage and fewer tarry by products in the triazole crude
• Isomer content 0.3% maximum: avoids the isomeric triazoles that would dilute the UV extinction coefficient of the stabiliser
• Low free acid 0.05% maximum: fewer side reactions in the acid catalysed coupling step
• Low water content: no hydrolysis during the azo coupling or the reduction stage
• Nitrogen blanketed drums: limited oxidation during transport and storage, reflected in a low and stable acid value
• Consistent reactivity: the plant does not have to re adjust the charge ratio between campaigns

Used in the synthesis of benzotriazole UV absorbers and in benzophenone type stabiliser routes, as well as in the preparation of intermediates for plastic additives where an ortho chloro aldehyde is required as the coupling partner.

For benzotriazole routes the aldehyde is typically coupled with a diazonium salt at 0 to 5 degrees C, then reduced and cyclised in a single pot; keeping the aldehyde dry and acid free is the main lever on cyclisation yield. Our technical note summarises the effect of acid content on triazole assay, based on laboratory trials.

Packed in 25 kg plastic drums and 250 kg iron drums with phenolic epoxy lining, all nitrogen blanketed. Drums are labelled with lot number, assay, water content, production date and GHS hazard information.

Store below 25 degrees C under nitrogen where possible, away from light and oxidisers. The material is an irritant and a lachrymator; handle under local exhaust ventilation. Shipments leave within 7 to 15 working days with COA, SDS and packing list.

The Certificate of Analysis reports assay, isomer distribution, free acid, water, colour and density, with the chromatogram attached. A retention sample of 200 g is stored for 24 months.

We supply a GHS safety data sheet, an impurity profile statement for registration files, and technical support on coupling conditions. Independent third party analysis can be arranged for customers who require it before qualification.