2-Amino-3,5-dibromobenzaldehyde (CAS 50910-55-9): Applications, Synthesis and Selection Guide
September 30, 2026 · Sourcing Guide
Summary. 2-Amino-3,5-dibromobenzaldehyde (CAS 50910-55-9, C7H5Br2NO, MW 278.93) is a brominated ortho-amino aromatic aldehyde supplied as an off-white to pale yellow crystalline powder. It is used primarily as a pharmaceutical intermediate for ambroxol hydrochloride and bromhexine hydrochloride, and as a key building block for 6,8-dibromoquinolines, 6,8-dibromoquinazolines, brominated indole/benzimidazole scaffolds, Schiff base ligands and brominated dye or probe intermediates. Its value comes from three reactive handles in one molecule: an aldehyde group, a primary aromatic amine in the ortho position, and two aryl bromides at the 3- and 5-positions. This combination enables reductive amination, intramolecular cyclocondensation and cross-coupling (Suzuki–Miyaura, Buchwald–Hartwig, Ullmann) without a separate bromination step.
Basic information
| Item | Value |
|---|---|
| Product name | 2-Amino-3,5-dibromobenzaldehyde |
| Synonyms | 3,5-Dibromo-2-aminobenzaldehyde; 2-amino-3,5-dibromobenzaldehyde |
| CAS number | 50910-55-9 |
| Molecular formula | C7H5Br2NO |
| Molecular weight | 278.93 g/mol |
| Appearance | Off-white to pale yellow crystalline powder |
| Assay (HPLC) | ≥98.0% (typical commercial grade; higher grades on request) |
| Functional groups | Aromatic aldehyde; primary aromatic amine (ortho to aldehyde); two aryl bromides (3,5) |
| Solubility | Soluble in dichloromethane, DMF, DMSO, THF, ethyl acetate; slightly soluble in water |
| Storage | Sealed, dry and dark; long-term storage recommended at 2–8 °C under inert gas |
| Packaging | 25 kg fibre drum with inner liner; 1–5 kg foil bag on request |
| HS code | 2922.29 (aromatic amino-aldehydes; confirm classification with local customs) |
| Main uses | Pharmaceutical intermediate; heterocycle building block; ligand and dye intermediate |
| Downstream products | Ambroxol hydrochloride (CAS 23828-92-4); bromhexine hydrochloride (CAS 611-75-6) |
| Documents | COA, MSDS, HPLC and NMR data available |
1. Product overview
2-Amino-3,5-dibromobenzaldehyde is a trifunctional aromatic building block. The aldehyde is electrophilic and reacts with amines, hydrazides and active methylene compounds. The amino group is both a nucleophile and an internal directing group, and it sits ortho to the aldehyde, which is the structural requirement for direct ring closure to nitrogen heterocycles. The 3,5-dibromo substitution is pre-installed, so downstream chemistry does not need to handle bromine on an oxidation-sensitive aldehyde.
2. Industrial synthesis (brief)
The main commercial route is selective bromination of 2-aminobenzaldehyde in acetic acid or in an HBr/hydrogen peroxide system. The amino group is strongly activating and ortho/para directing, so bromine enters the 3- and 5-positions; equivalents, temperature and solvent are controlled to suppress over-bromination and oxidation of the aldehyde. A second route starts from 3,5-dibromoanthranilic acid, where the carboxyl group is converted to the aldehyde through the acid chloride or the ester (selective reduction), giving the same product. Crude material is washed to remove residual halogen and acid, decolourised, and recrystallised from ethanol or an ethyl acetate/hexane system. Quality control covers assay (HPLC), identity (NMR/IR), water content (Karl Fischer) and residual solvents.
3. Why it works: application principles
- Reductive amination. The aldehyde condenses with a primary or secondary amine to an imine, which is reduced to a benzylamine. This one step builds the C–N bond that defines both ambroxol and bromhexine, and it is why this aldehyde is the standard starting material for those APIs.
- Intramolecular cyclocondensation. Because the amine is ortho to the aldehyde, reaction with ketones, amidines, ureas, nitriles or formamide closes a second ring directly, giving quinoline (Friedländer-type) or quinazoline systems with the two bromines already in place at the 6- and 8-positions.
- The two bromine atoms. They increase lipophilicity and membrane permeability, block oxidative metabolism on the aromatic ring, participate in halogen bonding with protein pockets, and act as clean handles for cross-coupling or halogen–metal exchange. The heavy-atom effect of bromine is also used in phosphorescent and fluorescent probe design.
- The aniline nitrogen. It is a hydrogen-bond donor and a salt-forming site; downstream products are usually isolated as hydrochlorides to improve solubility and crystallinity.
4. Application areas in detail
4.1 Expectorant and mucolytic APIs (main application)
Reductive amination of the aldehyde gives the benzylamine core of two widely prescribed respiratory drugs:
- Ambroxol hydrochloride (CAS 23828-92-4) — formed with trans-4-aminocyclohexanol; increases surfactant synthesis by type II pneumocytes, stimulates serous bronchial secretion, improves mucociliary clearance and shows antioxidant and local anaesthetic activity.
- Bromhexine hydrochloride (CAS 611-75-6) — formed with methylamine followed by N-alkylation with cyclohexyl halide; a mucolytic that reduces mucus viscosity and improves secretion transport.
Downstream finished products built on these APIs include tablets, capsules, syrups and oral solutions, injections, inhalation (nebuliser) solutions, effervescent tablets and sustained-release capsules, plus fixed-dose combinations with antibiotics (amoxicillin, cefixime, azithromycin, levofloxacin) and with bronchodilators. Veterinary respiratory products for swine, poultry and horses use the same intermediates.
4.2 Brominated nitrogen heterocycles for drug discovery
The ortho-aminoaldehyde motif is a classic annulation partner. Cyclocondensation gives 6,8-dibromoquinolines, 6,8-dibromoquinazolin-4(3H)-ones, brominated indoles, benzimidazoles and benzoxazoles, which serve as scaffolds for kinase inhibitors, antimicrobials, antimalarials, anti-inflammatory and anticancer leads. The bromine positions then allow parallel decoration by cross-coupling to build compound libraries.
4.3 Agrochemical intermediates
Brominated benzoxazinone, quinazolinone and quinoline cores derived from this aldehyde are used in fungicide, insecticide and herbicide discovery programmes and in plant growth regulator chemistry, where the bromine substituents improve lipophilicity and field persistence of the active ingredient.
4.4 Cross-coupling feedstock
The two aryl bromides undergo Suzuki–Miyaura, Buchwald–Hartwig, Ullmann, cyanation and carbonylation reactions. This makes the compound a convenient difunctional building block for introducing aryl, vinyl, amine, nitrile or ester groups onto a pre-formed aldehyde/amine skeleton, widely used in medicinal chemistry and in the synthesis of functional dyes.
4.5 Schiff base ligands and metal complexes
Condensation with amino acids, diamines, hydrazides or thiosemicarbazide gives polydentate Schiff base ligands. Their copper, zinc, nickel, cobalt or iron complexes are studied and used as catalysts, and as antimicrobial, antioxidant and DNA-binding agents; related imine derivatives are applied as colorimetric and fluorescent sensors for metal ions.
4.6 Dye, probe and optical material intermediates
The compound is used to prepare brominated quinoline, coumarin and azo dye intermediates, and as a precursor in organic electroluminescent and phosphorescent material research, where the heavy bromine atom promotes intersystem crossing.
4.7 Reference standards and impurity studies
Because it is a process-related substance in ambroxol and bromhexine manufacture, it is also used as a reference standard for impurity profiling, method validation and stability studies in pharmaceutical quality control.
5. Comparison with alternative building blocks
| Alternative | Structure difference | Practical consequence |
|---|---|---|
| 2-Aminobenzaldehyde (CAS 529-23-7) | No bromine | Requires a separate bromination step: corrosive bromine handling, over-bromination and aldehyde oxidation, extra unit operation |
| 2-Amino-5-bromobenzaldehyde | One bromine only | Lower lipophilicity, only one coupling position, final products need further halogenation |
| 3,5-Dibromo-2-hydroxybenzaldehyde (dibromosalicylaldehyde, CAS 90-59-5) | Phenol instead of aniline | Cannot be used for the reductive amination route to ambroxol/bromhexine; used mainly in fungicide intermediates and Schiff bases |
| 3,5-Dibromoanthranilic acid | Carboxyl instead of aldehyde | Requires acid-chloride or ester reduction to reach the aldehyde; longer route, more steps, lower atom economy |
| 2-Nitro-3,5-dibromobenzaldehyde | Nitro instead of amino | Needs a reduction step before cyclisation and reductive amination |
| 3,5-Dibromobenzaldehyde | No ortho-amino group | Good coupling substrate but cannot close nitrogen heterocycles directly |
Net advantage: one commercially available intermediate already carries the 3,5-dibromo pattern, the aldehyde and the ortho-amine, so downstream users save a hazardous bromination step, improve regioselectivity and overall yield, and obtain more consistent batch quality.
6. Handling and storage
Store sealed in a cool, dry, dark place, preferably 2–8 °C for long-term storage, under nitrogen if available; aromatic aldehydes slowly oxidise to the corresponding acid on exposure to air and light. Keep away from strong oxidisers and strong bases. Use local exhaust ventilation, gloves and eye protection; refer to the MSDS for occupational limits.
FAQ
Q1. What is 2-amino-3,5-dibromobenzaldehyde (CAS 50910-55-9) used for? It is used mainly as a pharmaceutical intermediate for ambroxol hydrochloride and bromhexine hydrochloride, and as a building block for brominated quinolines, quinazolines and Schiff base ligands.
Q2. Is it the key intermediate for ambroxol hydrochloride and bromhexine hydrochloride? Yes. The aldehyde group undergoes reductive amination with trans-4-aminocyclohexanol (ambroxol) or with methylamine followed by N-alkylation (bromhexine), so it supplies the entire 2-amino-3,5-dibromobenzyl fragment of both APIs.
Q3. Why are the bromine atoms at the 3- and 5-positions important? They raise lipophilicity and metabolic stability, support halogen bonding with biological targets, and provide two cross-coupling positions. Pre-installing them avoids a late-stage bromination of a sensitive aldehyde.
Q4. How does it differ from dibromosalicylaldehyde? Dibromosalicylaldehyde carries a phenol group; this product carries a primary aromatic amine. Only the amino version can be converted into the benzylamine pharmacophore of ambroxol and bromhexine.
Q5. What purity and packaging are typical? Standard commercial grade is ≥98.0% by HPLC, packed in 25 kg fibre drums with inner liner; 1–5 kg foil bags and custom purity grades are available on request.
Q6. How should it be stored? Sealed, dry, protected from light and air; 2–8 °C is recommended for long-term storage. Oxidation to the corresponding acid is the main degradation pathway.
Q7. Can it be used directly as an active pharmaceutical ingredient? No. It is a chemical intermediate, not a pharmacopoeial API. Downstream steps (reductive amination, salt formation, purification) are required, and pharmaceutical use is subject to the buyer's own regulatory filings.
Q8. Are COA, MSDS and analytical spectra available? Yes, a COA with HPLC assay, an MSDS, and NMR/IR data are provided with each shipment.
Q9. What is the HS code? HS 2922.29 is the usual classification for aromatic amino-aldehydes; final classification should be confirmed with the importing customs authority.
Keywords: 2-amino-3,5-dibromobenzaldehyde, CAS 50910-55-9, 3,5-dibromo-2-aminobenzaldehyde, ambroxol intermediate, bromhexine intermediate, dibromobenzaldehyde, ortho-aminobenzaldehyde, brominated quinoline building block, pharmaceutical intermediate, Schiff base ligand.