P-toluenesulfonyl hydrazide (TSH, also called tosylhydrazide or 4-methylbenzenesulfonohydrazide, CAS 1576-35-8) does two jobs that rarely appear in the same sentence. In a plastics or rubber plant it is a chemical blowing agent that releases nitrogen when heated. In a research lab it is the standard reagent for making tosylhydrazones.

Identity and Core Properties

TSH has the molecular formula C₇H₁₀N₂O₂S (structure CH₃C₆H₄SO₂NHNH₂) and a molar mass of 186.23 g/mol. It is a white solid, industrially prepared from p-toluenesulfonyl chloride and hydrazine. Our own sulfonyl chloride is listed as P-Toluene sulfonyl chloride (PTSC).

One point worth stating plainly, because supplier data sheets are not always consistent: the melting point and the decomposition temperature of TSH are two different numbers. Reference suppliers report melting at roughly 108–111 °C, while the temperature at which gas evolution proceeds in a heating test is higher. Our specification measures that at 143–147 °C (5 °C/min, in air). Mixing them up is a common cause of poor foam trials.

Solubility: our data indicates it is slightly soluble in water and dissolves in ethanol, acetone and ether. Public references agree that it dissolves in many organic solvents but is poorly soluble in water and alkanes; at least one catalog lists it as water-soluble, so confirm solvent behavior on your own sample before scaling a recrystallization or reaction.

TSH as a Blowing Agent: Where It Sits

A chemical blowing agent works by staying inert during mixing and then decomposing, at a known temperature, into gas that expands the polymer. That is why decomposition temperature matters more than almost any other line on the data sheet. Sulfonyl hydrazides are attractive because the family offers a range of decomposition temperatures, which lets a converter match the agent to the processing temperature.

Within that family, TSH occupies a middle position. Its 143–147 °C decomposition range sits below the roughly 161 °C reported for a polymer-bound OBSH grade, and its 120–130 ml/g gas yield is higher than that grade's roughly 98 ml/g. Two cautions apply. The OBSH figure is for a formulated product (about 75% active ingredient plus binder), and the tests were not run under identical conditions, so treat the comparison as a guide to selection, not a guarantee. The practical conclusion still holds: TSH suits compounds that cure or process in the mid-140 °C region, where a lower-temperature agent would decompose too early and a higher-temperature one would barely activate.

If your process runs cooler than the decomposition range, activators (often called kickers) can lower the decomposition temperature of sulfonyl hydrazide agents. If it runs hotter, a higher-temperature agent is the better starting point. Our guide to choosing a forming agent by decomposition temperature walks through that matching step, and the full range is on our Forming agent & Blowing agent page.

Where TSH is used in practice. Commercial TSH-based blowing agents are marketed for EPDM, NBR and CR rubber foams, including EPDM weather strips, wire coverings, thermal insulation and rubber sponges. Patent literature also describes tosyl-group foaming agents for foamed polyolefin insulation on high-frequency telecom cable.

Related Jinli blowing agents for comparison when you are specifying a grade:

• Benzene sulfonyl hydrazide (BSH), CAS 80-17-1: a lower-temperature option (see our BSH practical guide).
• P-Toluenesulfonyl Semicarbazide (RA/TSSC), CAS 10396-10-8.
• 4,4'-Oxybis(benzenesulfonyl hydrazide) (OBSH), with a detailed OBSH guide.
• Zinc P-Toluenesulfinate Salt (ZTS/TM).

TSH in Organic Synthesis

The laboratory use is the better known one. TSH condenses with aldehydes and ketones to give tosylhydrazones (general structure RR'C=N–NH–Ts). Those intermediates then feed several named transformations:

• Bamford–Stevens reaction: base-induced decomposition of tosylhydrazones to alkenes, first reported in 1952, with nitrogen and p-toluenesulfinate as by-products.
• Shapiro reaction: the alkyllithium variant, introduced in 1967, which generally gives the less substituted alkene and has been used in complex natural-product synthesis.
• Diazo surrogates: tosylhydrazone salts serve as a safer way to handle diazo chemistry, for example in metal-carbene cyclopropanation.

Our product page also notes use as an intermediate in chemical synthesis, in corrosion inhibition and in pharmaceutical intermediates. A byproduct worth noting from the reactions above is p-toluenesulfinate, which is a commercial chemical in its own right: see Sodium p-Toluenesulfinate (CAS 824-79-3).

Handling, Storage, and Safety

Because TSH is a decomposing, nitrogen-releasing solid, handle it as a heat-sensitive material, not as an ordinary inert powder.

• Hazard classification: published hazard statements include H242 (heating may cause a fire) and H301 (toxic if swallowed), and the compound is shipped under UN 3226, Class 4.1. Always work from the current safety data sheet for the grade you buy.
• Storage: keep it dry, cool and well ventilated, away from ignition sources and oxidizing agents. One reagent supplier recommends below 15 °C in a cool, dark place.
• Exposure: avoid inhalation, ingestion, and skin or eye contact, and follow standard laboratory and plant safety procedures.
• Process practice: never let dust accumulate near heated equipment, and run small-scale foam trials before changing the loading or activator in production.

Choosing a Supplier: What to Ask For

For a blowing agent, the specification lines that predict foam quality are decomposition temperature, gas volume, moisture and particle consistency from batch to batch. Ask any supplier for a certificate of analysis that reports decomposition temperature with its test method and heating rate, because values measured under different conditions are not comparable. Request a sample for your own foam trial rather than relying on the data sheet alone.

About Jinli Chemical. Jiaxing Jinli Chemical Co., Ltd. was established in 2002 and has operated from its current site in the Jiaxing Port Area chemical park since 2011. The site covers 22,000 square meters with an annual output of 19,000 tons. The company holds ISO 9001, ISO 14001 and ISO 45001 certification, is recognized as a national high-tech enterprise, and supplies customers in the USA, EU, Korea, Japan and Southeast Asia. It collaborates with Zhejiang University of Technology and Jiaxing University; see our Technology page for R&D details.

To discuss TSH specifications, samples or quotations, visit the TSH product page or our Contact page, or call 0086-573-85580888. For more technical articles, browse our Industry News.