MolDraw › Chemistry tools › Condensed Formula to Structure Converter
Condensed Formula to Structure Converter
In short: Type a condensed formula as you would write it in class, such as CH3CH2OH or (CH3)2CHCOOH. You get the skeletal structure, the SMILES, the molecular formula, the molar mass and the IUPAC name. If the formula fits more than one molecule, all of them are shown.
CH3COOCH2CH3 is ethyl acetate, SMILES CCOC(C)=O, C4H8O2, 88.106 g/mol. (CH3)2CHCOOH is 2-methylpropanoic acid, CC(C)C(=O)O.Use capital letters for elements. Bonds: - = ≡ (or #). Groups such as Ph, Me, Et, iPr, tBu, Ac, OMe, NO2, CN, COOH, CHO and CONH2 are understood.
Examples:
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How to use the condensed formula converter
- Type a condensed formula, for example
CH3CH(NH2)COOH, or press one of the examples. - Press Draw structure (or Enter). The line Read as shows how the formula was split into groups.
- Check the skeletal drawing, SMILES, molecular formula, molar mass and IUPAC name. If the formula is ambiguous, every possible molecule is shown; click the one you mean.
- Press Copy SMILES, Download .mol or Download .svg, or open the structure in the MolDraw editor.
What a condensed formula is
A condensed formula (or semi-structural formula) writes a molecule as a row of groups instead of drawing every bond. Each carbon is followed by its hydrogens and by the atoms bonded to it, and the groups are read left to right. CH3CH2OH means CH3–CH2–OH, ethanol. A molecular formula such as C2H6O only counts atoms and cannot be drawn without guessing.
How the tool reads a formula
| Rule | Example | Read as |
|---|---|---|
| H atoms belong to the atom just before them | CH3CH2OH | CH3–CH2–O–H |
| Each new carbon bonds to an earlier atom that still has a free valence | CH3OCH3 | CH3–O–CH3 |
| Double and triple bonds come from valences (C 4, N 3, O 2, halogens 1) | CH3CHO, CH3CCH | CH3–CH=O, CH3–C≡CH |
| CO, COO, CONH2 after a carbon are carbonyl groups | CH3COOCH2CH3 | CH3–C(=O)–O–CH2CH3 |
| (group)n at the start: n groups on the next atom | (CH3)3COH | three CH3 on C, then OH |
| (group) after an atom: a branch on that atom | CH3CH(NH2)COOH | NH2 on the second carbon |
| (unit)n with two free bonds: a chain | CH3(CH2)4CH3 | hexane |
| Groups written backwards at the start | HOOC-CH2-COOH, Cl2C=CCl2 | malonic acid, tetrachloroethene |
| A charge at the end, or a metal salt | CH3COO-, CH3COONa | acetate; sodium acetate as Na+ and acetate |
Abbreviations
Ph and C6H5 phenyl, C6H4 benzene ring with two groups (add o-, m- or p-), C6H11 cyclohexyl, Me methyl, Et and C2H5 ethyl, Pr propyl, iPr isopropyl, Bu butyl, tBu tert-butyl, Ac acetyl, Bz benzoyl, Bn benzyl, OMe, OEt, OAc, NHAc, NO2 nitro, SO3H, and the groups OH, NH2, CN, CHO, COOH, COCl, CONH2 written atom by atom. C3H7 and C4H9 are flagged as ambiguous because they can be several different groups.
When a formula is ambiguous
The tool tries every way of joining the groups that keeps normal valences. If two different molecules fit, it says so and shows both. It never picks one silently. Readings that only work with an O–O bond (a peroxide) are ignored when a normal reading exists, and the page says how many were ignored.
Worked examples
CH3COOCH2CH3
The C after CH3 carries both O atoms: one C=O and one O that links to CH2CH3.
Ethyl acetate, CCOC(C)=O, C4H8O2, 88.106 g/mol
(CH3)2CHCOOH
Two CH3 groups sit on the CH, which carries the COOH group.
2-Methylpropanoic acid, CC(C)C(=O)O, C4H8O2
CH3(CH2)4CH3
(CH2)4 is four CH2 units in a row.
Hexane, CCCCCC, C6H14, 86.178 g/mol
CH3C≡CH
The middle carbon has only two neighbours, so the bond to CH is triple. CH3CCH gives the same answer.
Propyne, CC#C, C3H4
CH2=CHCH2Cl
The = sign fixes the double bond; Cl sits on the last CH2.
3-Chloroprop-1-ene (allyl chloride), C=CCCl
C3H7OH
C3H7 can be propyl or isopropyl.
Ambiguous: propan-1-ol CCCO or propan-2-ol CC(C)O
Limitations
- Rings are read only through abbreviations (Ph, C6H5, C6H4, C6H11). A ring written atom by atom, such as cyclohexane as (CH2)6, is not closed.
- Stereochemistry is never taken from a condensed formula. R/S and E/Z are left undefined, and the page says when they exist.
- Molecular formulas (C2H6O, C6H12O6) and inorganic formulas such as H2SO4 or CuSO4·5H2O are not drawn.
- Only one charge, written at the end, is read (for example CH3COO- or CH3NH3+), plus Na, K or Li salts.
- The IUPAC name is looked up in PubChem and needs an internet connection. A structure that is not in PubChem gets no name. The drawing, SMILES, formula and masses are worked out in your browser.
Want to edit the structure? Open it in MolDraw, the free online chemical structure editor, to add arrows, labels or stereo bonds.
Open MolDraw editorFrequently asked questions
How do I turn a condensed formula into a structure?
Type it as you would write it, for example CH3COOCH2CH3, and press Draw structure. Each carbon is joined to the group written before it, H atoms and groups such as OH or Cl sit on the atom they follow, and double or triple bonds are added where the valences need them. CH3COOCH2CH3 gives ethyl acetate, CCOC(C)=O.
What is the difference between a condensed formula and a molecular formula?
A molecular formula only counts atoms: C2H6O. A condensed formula also shows how they are joined: CH3CH2OH is ethanol and CH3OCH3 is dimethyl ether, both C2H6O. Only a condensed formula (or a full structure) can be drawn. For a molecular formula, use the molecular formula to structure tool to list possible isomers.
How are brackets read in formulas like (CH3)2CHCOOH or CH3(CH2)4CH3?
A bracket with a number repeats the group. (CH3)2 at the start puts two methyl groups on the next carbon, so (CH3)2CHCOOH is 2-methylpropanoic acid. A group in brackets after an atom, as in CH3CH(NH2)COOH, is a branch on that atom. A unit with two free bonds, such as (CH2)4, is a chain: CH3(CH2)4CH3 is hexane.
Why does the tool say my formula is ambiguous?
Some formulas fit more than one molecule. C3H7OH can be propan-1-ol or propan-2-ol, and CH3C6H4OH can be the ortho, meta or para cresol. The tool shows every reading and does not pick one for you. Write the group out, for example CH3CH2CH2OH or (CH3)2CHOH, or add o-, m- or p- before a C6H4 formula.
Does the condensed formula converter show stereochemistry?
No. A condensed formula does not say which enantiomer or which cis/trans isomer is meant, so the structure is drawn without R/S or E/Z and the page tells you when a stereocentre or a stereogenic double bond is present. CH3CH(NH2)COOH is alanine with an undefined stereocentre.
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