Sodium hypophosphite contains phosphorus with a +1 oxidation state and its chemical formula includes phosphorus, oxygen, hydrogen, and sodium. It is generally neutral in aqueous solution, with a pH of 6-8, making it neither an acidic nor alkaline inorganic salt. It ionizes in water to release sodium and hypophosphite ions. Currently, it is mainly used as a chain transfer agent in polycarboxylate superplasticizers. So, what are the decomposition products of sodium hypophosphite at high temperatures?

Because it contains low-valence phosphorus, it has relatively strong reducing properties and its thermal stability is lower than that of ordinary orthophosphate and hydrochloric acid. Therefore, it may decompose when the temperature rises. Generally, above 200℃, sodium hypophosphite undergoes a thermal decomposition reaction, and the decomposition products typically include harmful gases such as PH3 and sodium phosphate. Of course, we rarely use it at such high temperatures. However, in special circumstances, such as a fire, thermal decomposition may still occur, producing harmful gases. In such cases, we must follow the operating instructions specified in the MSDS and take the correct emergency response measures.

Sodium hypophosphite, mercaptopropionic acid, and mercaptoacetic acid are all chain transfer agents in polycarboxylate superplasticizers, characterized by good water solubility, odorlessness, greenness, environmental friendliness, and safety. Each of these products has its advantages and disadvantages in concrete additives; sodium hypophosphite is more environmentally friendly and easier to use, while the latter two are cheaper but have poorer handling and safety. NaH2PO2.H2O contains a non-hydroxyl hydrogen atom in its molecular formula, making it non-ionizable; therefore, it is a normal salt, not an acid salt.