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O/P-Toluenesulfonamide: Isomer Ratios, Quality Specs and Industrial Uses – A Practical Buyer's Guide
If you buy O/P-Toluenesulfonamide (o/p-TSA, mixed toluenesulfonamide), the CAS number and the "99% purity" line are not what decide whether a batch works in your process. The ortho/para ratio, moisture, chloride and color usually matter more.
Key takeaways
- O/P-TSA is a mixture of two isomers (C7H9NO2S) with the same molecular weight, about 171.2 g/mol. The ratio is a performance variable, not a footnote.
- Jinli supplies it as a white crystalline powder, 99% min, in o/p ratios of 40/60, 30/70 or 20/80 (±3%).
- Its main uses are as a plasticizer and softener, as a resin modifier, and as a building block for derivatives such as N-ethyl-o/p-toluenesulfonamide and Chloramine-T.
- Always request a batch-specific Certificate of Analysis (COA) and Safety Data Sheet (SDS). Check the melting range and isomer ratio yourself on the first lot.
1. What is O/P-Toluenesulfonamide?
Toluenesulfonamide has a methyl group and a sulfonamide group (–SO2NH2) on a benzene ring. In the ortho isomer the two groups sit next to each other. In the para isomer they sit on opposite sides of the ring. "O/P-Toluenesulfonamide" is a deliberately blended mixture of the two.
The mixture exists for historical and practical reasons. Chlorosulfonating toluene gives both o- and p-toluenesulfonyl chloride. Reacting these with ammonia gives the two amides. The ortho isomer is the classic intermediate for saccharin, so the para isomer has long been available as the co-product (see the saccharin reference below). A mixed grade is therefore economical, and for many plasticizer jobs a blend actually performs better than a single pure isomer.
Pure isomers and mixtures differ in melting behavior. Pure p-toluenesulfonamide melts at roughly 137 °C and the pure ortho isomer near 157 °C. A blend of the two melts lower than either component alone, and this is why the mixed grade's melting-point specification is lower than a pure isomer's. For the pure para grade, see Jinli's 4-Toluenesulfonamide (CAS 70-55-3) page.
2. Jinli's Specification at a Glance
The figures below are taken from the O/P-Toluenesulfonamide product page. Batch values are always on the COA.
| Check point | Unit | Specification |
|---|---|---|
| Appearance | – | White crystalline powder |
| Purity | % min | 99 |
| Melting point | °C | 107 ± 5 |
| Water | % max | 0.3 |
| Color (APHA) | Pt/Co max | 30 |
| Chloride | ppm max | 100 |
| Ortho / Para ratio | ±3% | 40/60, 30/70 or 20/80 |
| Ash | % max | 0.1 |
| pH | – | 6.5–7.5 |
| Turbidity | max | 10 |
A note on CAS numbers. Mixed-isomer toluenesulfonamide is listed under more than one CAS number across suppliers and databases. Jinli lists 1333-07-9 and 8013-74-9. Because of this, use the CAS number together with the isomer ratio and the specification when you write a purchase specification. Do not rely on the number alone.
3. How to Read the Spec Sheet: What Each Parameter Tells You
| Parameter | What it signals | Where it hurts if out of range |
|---|---|---|
| Ortho/para ratio | Melting behavior, solubility and compatibility in the melt | Batch-to-batch changes in processing temperature and product feel |
| Water (≤0.3%) | Drying and packaging quality | Bubbles or hydrolysis in polyamide and resin melts; caking in storage |
| Chloride (≤100 ppm) | Residual sulfonyl chloride and salt carry-over from synthesis | Corrosion of equipment, side reactions in downstream chemistry |
| APHA color (≤30) | Trace organic impurities and oxidation | Yellowing in light-colored resins, pigments and clear polymers |
| pH (6.5–7.5) | Absence of residual acid or base | Catalyst interference in condensation and polymerization steps |
| Ash (≤0.1%) and turbidity | Inorganic residue and insolubles | Filter blocking, hazy solutions, surface defects |
The most common buying mistake is to compare suppliers on purity alone. Two lots can both read "99%" while differing in ortho/para ratio, water and chloride. Those three are the ones most likely to change how the product behaves in your equipment.
4. Choosing an Ortho/Para Ratio
These are general tendencies, not guarantees. Always confirm with a small trial in your own formulation.
| Grade (o/p) | General tendency | Typical consideration |
|---|---|---|
| 40/60 | More ortho: lower-melting mixture, easier to blend into melts and resin systems | Good when low-temperature processing or fast dissolution matters |
| 30/70 | Balanced | A sensible starting point when you have no history with the material |
| 20/80 | More para: more crystalline, higher-melting, closer to the pure para grade | Useful when handling and storage stability matter more than melt speed |
Jinli quotes a ±3% tolerance on the ratio. If your process is sensitive, ask for the ratio to be reported on every COA and agree an acceptance band in your purchase specification. If you need a ratio that is not listed, ask. A manufacturer that runs its own toluene sulfonation and refining can often adjust it.
5. Where O/P-Toluenesulfonamide Is Used
| Application | Role of o/p-TSA | Related Jinli product |
|---|---|---|
| Plasticizer and softener for engineering plastics and adhesives | Improves moldability and flexibility | Plasticizer Series |
| Resin modification (for example, amino-resin systems) | Reactive modifier that adjusts hardness and melt behavior | Plasticizer Series |
| Intermediate for N-alkyl derivatives | Starting material for liquid plasticizers | N-ethyl-o,p-toluenesulfonamide, N-ethyl-p-toluenesulfonamide |
| Intermediate for disinfectants | The para isomer is the usual precursor to Chloramine-T | Chloramine-T (CAS 7080-50-4) |
| Fine chemical and pharmaceutical intermediate chemistry | Sulfonamide building block for dyes, aroma chemicals and drug intermediates | P-Toluenesulfonyl chloride |
Plasticizer and polymer use
As a plasticizer, o/p-TSA sits between the polymer chains and lets them slide past each other more easily. This is why it is associated with polyamide, hot-melt and resin systems where processing temperature and flexibility have to be balanced. Jinli also lists enhanced solubility and thermal stability on its product page. For liquid plasticizer needs, the N-ethyl derivatives are easier to meter and mix. Your choice depends on whether you prefer a solid you can dry-blend or a liquid you can pump.
Intermediate chemistry
The sulfonamide nitrogen can be alkylated, chlorinated or condensed with aldehydes. That makes the compound a flexible starting point. Jinli's own range reflects this, with N-ethyl derivatives and Chloramine-T made from toluenesulfonamide feedstocks. Jinli's patent list includes a refining device for p-toluenesulfonamide and a synthesis device for N-ethyl o- and p-toluenesulfonamide (see Technology).
A word of caution on pharmaceutical claims
Sulfonamide chemistry is important in medicinal chemistry, and toluenesulfonamides are used as reagents and intermediates. This does not make o/p-TSA a drug or an active ingredient. If you plan to use it in a regulated pharmaceutical process, qualify it as a starting material under your own quality system and ask the supplier for the documentation your regulator expects.
6. Handling, Storage and Safety
- Read the SDS first. Hazard classification can differ by region and grade. Use the SDS for your lot rather than a generic summary.
- Control dust. Fine organic powders can irritate the eyes and respiratory tract, and dust clouds are a combustion hazard. Use local exhaust, avoid creating airborne dust, and wear gloves, safety glasses and a suitable dust mask or respirator.
- Keep it dry. The product is specified at 0.3% water max. Store in sealed, original packaging in a cool, dry, ventilated place, away from strong oxidizers, and reseal opened bags promptly.
- Know the end-use exposure. Toluenesulfonamide-formaldehyde resins are a recognized contact allergen in some cosmetic products. If your finished product touches skin, review the regulations that apply in your market.
7. Incoming Inspection Checklist for a First Order
- Check the COA against your purchase specification, and confirm the ortho/para ratio is stated.
- Observe appearance: it should be white, free-flowing and free of visible lumps or dark specks.
- Measure the melting range on a retained sample and compare it with the supplier's figure.
- Measure moisture by Karl Fischer titration.
- Verify the isomer ratio and purity by HPLC if your process is ratio-sensitive.
- Keep a retained sample from each lot so you can trace any later processing change.
8. Frequently Asked Questions
Is O/P-Toluenesulfonamide the same as p-toluenesulfonamide?
No. O/P-TSA is a mixture of ortho and para isomers, while p-toluenesulfonamide is the single para isomer (CAS 70-55-3). The mixture melts lower and is often preferred as a plasticizer.
Which ratio should I start with?
If you have no history with the material, a 30/70 blend is a reasonable starting point. Trial a more ortho-rich or more para-rich grade only if you need to adjust melt behavior or handling.
Why does the same material show different melting points in different documents?
Pure isomers and mixed grades melt at different temperatures, and the ratio shifts the range. Quote the melting point together with the ortho/para ratio, and check it on your own lot.
Can I get a sample, a COA and an SDS?
Yes. Contact Jinli through the details below and state your application and the ratio you need.
9. About Jiaxing Jinli Chemical Co., Ltd.
Jiaxing Jinli Chemical Co., Ltd. is a sulfonyl-chemistry manufacturer located in the Jiaxing Port Area Chemical Park, Zhejiang, China. Its range covers plasticizers, blowing agents, chemical intermediates, disinfectants and related products. The company's Technology page states the following:
- ISO 9001 (quality), ISO 14001 (environment) and ISO 45001 (occupational health and safety) management-system certifications.
- Recognition as a national high-tech enterprise, with research cooperation with Zhejiang University of Technology and Jiaxing University.
- Utility-model patents covering production and refining equipment for toluenesulfonamide products, and process-control software registrations for sulfonation and related reactions.
Learn more on the About page, or browse technical updates in Industry News.
