Sourcing 4-difluoromethoxy-3-hydroxybenzaldehyde (CAS 151103-08-1) reliably is a recurring task for procurement teams supporting pharmaceutical synthesis programs, because this small benzaldehyde derivative sits at an early but critical position in several fluorinated API routes. Written more formally as 4-(difluoromethoxy)-3-hydroxybenzaldehyde, the compound combines a phenolic hydroxyl, an aromatic aldehyde and a difluoromethoxy group on a single ring, which makes it a versatile building block but also places specific demands on purity, isomer control and handling. This article summarizes what the intermediate is, where it is used, how it is typically made, and which quality and sourcing points buyers can focus on when qualifying a supplier.
What Is 4-(Difluoromethoxy)-3-hydroxybenzaldehyde?
4-(Difluoromethoxy)-3-hydroxybenzaldehyde is a substituted benzaldehyde with the molecular formula C8H6F2O3 and a molecular weight of approximately 188.13 g/mol. The molecule carries three reactive or functionalizable positions: the aldehyde group, which can undergo condensations, reductive aminations and oxidations; the free phenolic hydroxyl at the 3-position, which is available for alkylation or acylation; and the difluoromethoxy group at the 4-position, which is generally carried through subsequent steps unchanged and contributes the metabolic stability and lipophilicity profile that medicinal chemists often seek from OCHF2 substitution.
Commercially, the material is usually offered as an off-white to light-colored crystalline solid. Because the phenol and aldehyde are both present, the compound can be sensitive to prolonged exposure to air, light and elevated temperature, so suppliers and buyers alike normally treat it as a product to be stored cool, dry and well sealed.
Where the Intermediate Is Used
The best-known application of this compound is as an early intermediate in synthesis routes described in the literature for roflumilast, a PDE4 inhibitor class API, where the free phenol is alkylated with a cyclopropylmethyl group and the aldehyde is subsequently elaborated toward the final molecule. Beyond that well-documented route, the combination of a difluoromethoxy group with an ortho-positioned phenol and an aldehyde makes the compound a candidate building block that may be evaluated in other fluorinated drug discovery programs, agrochemical research and specialty materials work. As with any pharmaceutical intermediate, the exact role and the required specification depend on the customer’s own route, and downstream suitability is always confirmed by the buyer’s process development team.
For sourcing purposes, the practical consequence is that most demand comes from API manufacturers and CDMOs that need consistent multi-kilogram to hundred-kilogram quantities, with an emphasis on lot-to-lot reproducibility rather than one-off availability. AXIA CHEM supplies 4-(difluoromethoxy)-3-hydroxybenzaldehyde as part of its specialty fine chemicals range, alongside related aromatic and heterocyclic intermediates.
How It Is Typically Made: The Difluoromethylation Step
Published routes to this intermediate commonly start from 3,4-dihydroxybenzaldehyde (protocatechuic aldehyde) and install the difluoromethyl ether by O-difluoromethylation. Classical procedures use chlorodifluoromethane or newer difluorocarbene reagents under basic conditions, and the reaction is frequently run in two-phase or polar aprotic systems where selectivity between the two phenolic hydroxyls must be managed. Because the 3-OH and 4-OH positions compete, the crude product can contain the regioisomeric 3-(difluoromethoxy)-4-hydroxybenzaldehyde as well as the bis-difluoromethylated by-product, and separating these efficiently is one of the main process challenges.
Where two-phase alkylation conditions are used, quaternary ammonium phase transfer catalysts such as tetrabutylammonium bromide (TBAB, CAS 1643-19-2) can be considered to move the phenolate into the organic phase and improve conversion at moderate temperature. For buyers, the takeaway is less about the chemistry itself and more about its fingerprints in the product: the choice of difluoromethylation method influences which isomers, residual solvents and inorganic residues need to be controlled in the final specification.
Quality Points Buyers Should Check
When qualifying a lot of CAS 151103-08-1, procurement and QC teams typically review the following points on the certificate of analysis and, for critical applications, verify them in-house:
- Assay and chromatographic purity: HPLC purity is the headline number, but the impurity profile matters more than the single figure. Ask the supplier to identify the main individual impurities rather than reporting only a total.
- Regioisomer content: because the synthesis can produce the 3-OCHF2 / 4-OH isomer, a specific limit or test for regioisomers is worth requesting; isomeric impurities are difficult to purge downstream.
- Identity: confirmation by NMR, IR or MS against a reference, since closely related difluoromethoxy benzaldehydes look similar on paper.
- Residual solvents and moisture: aligned with the solvents actually used in the process; water content matters for downstream steps that are moisture sensitive.
- Appearance and stability: color drift on storage can signal oxidation of the aldehyde or phenol, so agreed retest intervals and storage conditions are useful contract points.
For pharmaceutical end use, buyers usually also ask whether the manufacturer can support change control notification and consistent starting material sourcing, even when the intermediate itself is purchased outside a GMP scope.
Practical Sourcing and Logistics Notes
4-(Difluoromethoxy)-3-hydroxybenzaldehyde is normally shipped as a solid in fiber drums or cartons with double PE liners, with pack sizes from 1 kg sample quantities up to 25 kg production packs. It is not classified as dangerous goods in typical commercial presentations, which simplifies air and sea freight, though buyers should always confirm the current SDS classification for their shipping lane. Lead times depend on whether the supplier holds stock or produces to order; for campaign-based API production, locking a rolling forecast with the supplier is usually more economical than spot buying. Sample evaluation, followed by a pilot lot and then commercial supply, remains the standard qualification path for this kind of intermediate.
Why AXIA CHEM
AXIA CHEM supplies quaternary ammonium salts, phase transfer catalysts and specialty fine chemical intermediates from audited manufacturing partners in China to customers in the Middle East and worldwide. For intermediates like CAS 151103-08-1, we provide pre-shipment COA review, retained samples, consistent single-source manufacturing where required, and responsive technical communication in English within one business day. Flexible pack sizes, export documentation support and experience with Gulf-region ports help keep qualification and repeat supply predictable. To request a quotation, current lead time or a sample of this intermediate, contact the AXIA CHEM team.
Regulatory disclaimer: These products are supplied for research, formulation development, industrial and non-regulated applications. Final suitability for pharmaceutical, oral care, cosmetic, food-contact or biocidal applications shall be verified by the buyer according to local regulations. AXIA CHEM does not claim that any product is FDA approved, USP/EP certified, GMP grade or approved for any specific regulated end use unless otherwise confirmed in writing with supporting documentation.
