4,5-Diamino-1-(2-hydroxyethyl)pyrazole Sulfate: FAQs

4,5-Diamino-1-(2-hydroxyethyl)pyrazole sulfate is a diaminopyrazole salt widely used as a primary intermediate in oxidative hair-coloring formulations and as a building block in heterocyclic chemistry research.

SKU

D181753

Chemical Class

Diaminopyrazole sulfate salt

Primary Application

Oxidative hair-coloring intermediate; heterocyclic synthesis building block

Functional Groups

Two primary amine groups, hydroxymethyl side chain, pyrazole ring, sulfate counterion

Physical Form

Solid salt (sulfate form provides improved stability vs free base)

Storage Recommendation

Cool, dry, well-ventilated area; protect from light and moisture

What Is 4,5-Diamino-1-(2-hydroxyethyl)pyrazole Sulfate?

4,5-Diamino-1-(2-hydroxyethyl)pyrazole sulfate is the sulfate salt form of a diaminopyrazole compound in which a 2-hydroxyethyl group is attached at the N-1 position of the pyrazole ring, and primary amine groups are present at the 4- and 5-positions. The sulfate salt form is preferred in commercial and research settings because it confers greater stability and improved handling characteristics compared with the free base.

The compound belongs to the broader class of heterocyclic diamines and is closely related to other aminopyrazole intermediates used in dye chemistry. Its bifunctional amine groups enable condensation and coupling reactions that generate chromophoric structures when oxidatively coupled with coupler molecules, making it a key primary intermediate (also called a dye precursor or oxidation base) in permanent hair-coloring chemistry.

Key Properties and Handling

Solubility: As a sulfate salt, the compound typically exhibits good aqueous solubility, which facilitates formulation in aqueous hair-coloring systems and stock solution preparation for laboratory assays. Exact solubility values should be confirmed from the certificate of analysis or by empirical testing.

Stability: The sulfate salt is more stable than the free base toward oxidation and hydrolysis. Nevertheless, solutions should be prepared freshly where possible, and the solid should be stored under cool, dry, and light-protected conditions. Exposure to air and moisture over extended periods may cause gradual degradation.

Reactivity: The two free amine groups are nucleophilic and can react with electrophiles, oxidants, and carbonyl-containing compounds. When handling, avoid contact with strong oxidizing agents under uncontrolled conditions. Standard laboratory PPE (gloves, eye protection, lab coat) is recommended.

Regulatory note: Cosmetic-use diaminopyrazole derivatives are subject to regulatory review in multiple jurisdictions; researchers using this compound in formulation development should consult applicable regulations.

Research and Industrial Applications

Hair-coloring chemistry: The most established application of 4,5-Diamino-1-(2-hydroxyethyl)pyrazole sulfate is as a primary intermediate in permanent oxidative hair dyes. In such formulations, the compound undergoes oxidative coupling with couplers (e.g., resorcinol derivatives, naphthols, or other couplers) in the presence of hydrogen peroxide to produce indamine or azomethine-type chromophores responsible for the final color deposited on the hair fiber. The hydroxyethyl substituent at N-1 modifies substantivity and influences the hue of the resulting dye.

Heterocyclic and medicinal chemistry: The diaminopyrazole scaffold is a versatile building block in synthetic chemistry. Researchers use such intermediates to prepare fused bicyclic systems (e.g., pyrazolo[3,4-d]pyrimidines, pyrazolopyrimidines) that have been explored as kinase inhibitors and other bioactive molecules. The 4,5-diamino substitution pattern allows cyclization with 1,3-biselectrophiles to construct bicyclic heterocycles.

Dye and pigment research: Beyond hair dye, diaminopyrazole compounds serve as precursors to azo and non-azo colorants studied for textile, analytical, and biological staining applications.

Storage, Safety, and Regulatory Guidance

Storage: Store the solid at room temperature or below in a tightly sealed container, protected from light, heat, and moisture. Refrigeration may extend shelf life; consult the product certificate of analysis for the recommended storage condition specific to the supplied lot.

Safety: Handle in accordance with the Safety Data Sheet (SDS) provided with the product. The compound contains reactive amine groups; avoid inhalation of dust and contact with skin and eyes. Work in a well-ventilated area or fume hood. In the event of skin contact, wash thoroughly with soap and water. Consult the SDS for full first-aid measures, disposal guidance, and transport classifications.

Waste disposal: Dispose of waste material in accordance with local, regional, and national regulations. Do not discharge to drain or environment without appropriate treatment.

Ordering and Specifications

4,5-Diamino-1-(2-hydroxyethyl)pyrazole sulfate is available from Aladdin Scientific under SKU D181753. When placing an order, please confirm the required quantity, purity grade, and any specific certificate of analysis requirements with our sales team or through the online portal.

For lot-specific purity, NMR, HPLC, and other analytical data, refer to the certificate of analysis available on the product page or request it from customer service. Bulk quantities and custom packaging may be available upon request; contact Aladdin Scientific technical sales for a quotation.

For research use only (RUO). Not intended for diagnostic, therapeutic, or food use unless otherwise specified.

Frequently asked questions

What is 4,5-Diamino-1-(2-hydroxyethyl)pyrazole sulfate used for?

It is primarily used as a primary oxidative intermediate in permanent hair-coloring formulations, where it undergoes oxidative coupling with color couplers to produce chromophores that deposit color on the hair fiber. In research, it also serves as a versatile diaminopyrazole building block for synthesizing heterocyclic compounds such as pyrazolopyrimidines, which are of interest in medicinal chemistry as potential kinase inhibitors.

Why is the sulfate salt form preferred over the free base?

The sulfate salt offers significantly improved chemical stability compared to the free base, as it is less prone to oxidation and hydrolysis during storage and handling. The salt form also typically has better flowability and handling characteristics as a solid, making it more practical for both laboratory and industrial use.

How should I prepare a stock solution of D181753 for laboratory use?

Because the sulfate salt is generally water-soluble, dissolving it in deionized or distilled water is recommended as a first approach. Prepare the solution freshly before use to minimize oxidative degradation, and if the solution must be stored, keep it protected from light and oxygen (e.g., under inert atmosphere or refrigerated in a sealed vial). Verify complete dissolution visually or by UV-Vis absorbance before use. Exact solubility limits should be confirmed experimentally for your specific conditions.

Is 4,5-Diamino-1-(2-hydroxyethyl)pyrazole sulfate regulated for cosmetic use?

Yes, diaminopyrazole oxidative dye intermediates are subject to cosmetic regulations in many regions, including the EU Cosmetics Regulation and equivalent frameworks in other jurisdictions. Researchers and formulators intending to use this compound in consumer products should consult the relevant regulatory lists and safety assessment requirements applicable in their market. Aladdin Scientific supplies this material for research use only.

What analytical methods are suitable for characterizing this compound?

Common analytical approaches include HPLC (with UV detection, typically monitoring aromatic amine absorbance in the 200–350 nm range), NMR spectroscopy (1H and 13C) to confirm the pyrazole ring substitution pattern and side-chain identity, and elemental analysis or mass spectrometry for molecular formula confirmation. Ion chromatography or titrimetric methods may be used to quantify the sulfate counterion. Lot-specific data are provided in the certificate of analysis supplied with each batch.

What precautions should I take when handling D181753 in the laboratory?

Always consult the product SDS before use. Wear appropriate PPE including chemical-resistant gloves, safety glasses or goggles, and a laboratory coat. Avoid generating dust and work in a well-ventilated area or under a fume hood. Keep away from strong oxidizing agents, acids, and bases unless intentionally reacting with them. In the event of accidental exposure, follow the first-aid instructions in the SDS and seek medical attention if necessary.

References

1. Zviak C. (Ed.) The Science of Hair Care. Marcel Dekker, New York, 1986. (General reference for oxidative hair dye chemistry and diaminopyrazole intermediates.)
2. Bolduc C, Shapiro J. Hair care products: waving, straightening, conditioning, and coloring. Clin Dermatol. 2001;19(4):431-436.
3. Comprehensive Medicinal Chemistry II, Vol. 7. Elsevier, 2006. (Reference for diaminopyrazole heterocyclic scaffolds in drug discovery.)

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.