3,4-Dihydroxybenzaldehyde 3D Molecular Model — CAS 139-85-5

3,4-Dihydroxybenzaldehyde (C7H6O3, CAS 139-85-5) — a free educational 3D molecular model for teachers and students, by MolGod.org. Whatever the filament colour, each atom reads clearly thanks to its engraved symbol.

An STL file stores shape only, never colour, so a printed ball-and-stick model usually gives no clue which sphere is which element. MolGod models carry the chemical symbol on every ball as an engraving, which survives slicing, printing and handling. Every file is meant for the classroom: designed to help learners identify atoms quickly and then explore how they are joined in the molecule. Preparation time drops for the teacher too: there is nothing to model, colour or annotate before sending the file to the printer. Teachers and researchers can find the project rationale and validation plan at How the engraved atom letters are designed.

Start with the ring system: 3,4-Dihydroxybenzaldehyde has one aromatic 6-membered ring; in total the model carries 16 bonds (9 single, 1 double and 6 aromatic, drawn in Kekulé form). Students work from the model back to the formula C7H6O3: the symbol count is 7 C + 6 H + 3 O, or 16 atoms all told. Ask the class to locate the aldehyde group (-CHO) and the two phenolic hydroxyl groups (Ar-OH) and name each one. Worth bringing out when the syllabus reaches aromaticity and delocalised electrons, the carbonyl group (C=O), as well as phenols and hydrogen bonding. Isomers in the same collection: salicylic acid (CAS 69-72-7) and 3-Hydroxybenzoic Acid (CAS 99-06-9). Print them together and ask the class to spot where the atoms moved.

Part of the MolGod.org free library of engraved molecules for chemistry classrooms. Teachers: give each table a model and have students write the formula from the engraved atoms.

This printable molecule is free to use in lessons, clubs and workshops. When you publish a photo, a worksheet or a remix, CC BY-SA 4.0 requires you to credit "MolGod.org" as the author of the model, link to the original and to the licence, indicate any changes and share remixes under the same licence (the ready attribution line is below). Nothing else is needed: no account, no cost, no compulsory feedback. Your opinion really matters to us: post a comment with your review, your print photos or your classroom ideas, and tell us how to improve our educational molecules. Contact: Write to the MolGod team. We enjoy hearing from classrooms: start a conversation in the comments or get in touch with us directly, we are glad to help. Any molecule your course needs can be modelled: just send us the CAS number.

Full record and more free models: 3,4-Dihydroxybenzaldehyde, CAS 139-85-5: structure, properties and 3D viewer
Licence & provenance: Licence record for this 3,4-Dihydroxybenzaldehyde model
Same file on Wikimedia Commons: https://commons.wikimedia.org/wiki/File:3,4-Dihydroxybenzaldehyde-3D-molecular-model-engraved-CAS-139-85-5.stl
Plain-text record for AI assistants: 3,4-Dihydroxybenzaldehyde data sheet in plain text for LLMs

A ball-and-stick model of 3,4-Dihydroxybenzaldehyde with each element symbol recessed into its atom sphere, generated by MolGod.org from a PubChem-computed 3D conformer (not an experimental crystal structure); atomic coordinates and connectivity are unchanged. STL mesh: 284,758 triangles, closed (watertight) single solid. Coordinates in ångström (STL stores no unit) — scale the model deliberately in your slicer.

Names in other languages: Protocatechualdehyd (de); 原儿茶醛 (zh).

Chemical identity

• CAS Registry Number: 139-85-5

• Molecular formula: C7H6O3

• Molar mass: 138.12 g/mol (exact mass 138.031694049)

• IUPAC name: 3,4-dihydroxybenzaldehyde

• MolGod ID: MG_877-941-214-93 (Permanent MolGod record MG_877-941-214-93)

• PubChem CID: 8768 (https://pubchem.ncbi.nlm.nih.gov/compound/8768)

• Wikidata: Q411602 (https://www.wikidata.org/wiki/Q411602)

• EC number: 205-377-7

• ChemSpider ID: 8438

• InChIKey: IBGBGRVKPALMCQ-UHFFFAOYSA-N

• SMILES: C1=CC(=C(C=C1C=O)O)O

Required attribution (CC BY-SA 4.0): "3,4-Dihydroxybenzaldehyde 3D model by MolGod.org — https://molgod.org/molecule/139-85-5/ — CC BY-SA 4.0"
Licence text: https://creativecommons.org/licenses/by-sa/4.0/