Naming organic compounds
Introduced| English | Meaning |
|---|---|
| prefix/ˈpriːfɪks/ | A letter group or naming element added at the beginning of a word or name. |
| suffix/ˈsʌfɪks/ | A letter group or naming element added at the end of a word or name. |
| alkane/ˈælkeɪn/ | The saturated, open-chain hydrocarbons studied here, with only single carbon–carbon bonds and general formula CₙH₂ₙ₊₂. |
| alkene/ˈælkiːn/ | The open-chain hydrocarbons with one carbon–carbon double bond studied here, with general formula CₙH₂ₙ. |
| alcohol/ˈælkəhɒl/ | An organic compound with a hydroxyl group bonded to a saturated carbon atom. |
Cracking the code of a name
- With millions of carbon compounds, chemists need a systematic way to name them.
- The name tells you the chain length and the family.
Organic naming route
Follow the route from structure to systematic name.
How many carbon atoms does the prefix "prop-" indicate?
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meth-(1), eth-(2), prop-(3), but-(4).
How many carbon atoms are in butane?
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but- means 4 carbons.
The prefix 前缀 = chain length
- The first part of the name shows how many carbon atoms: meth- (1), eth- (2), prop- (3), but- (4).
- So "propane" has 3 carbons, "butene" has 4.
A saturated compound has single C-C bonds; an unsaturated one has a C=C double bond
The suffix "-ol" tells you the compound is a(n):
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-ol means alcohol.
The suffix "-ene" tells you the compound is an ______.
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-ene means alkene.
The suffix 后缀 = family
- The ending shows the family: -ane (alkane 烷烃), -ene (alkene 烯烃), -ol (alcohol 醇), -oic acid (carboxylic acid).
- So "ethanol" is a 2-carbon alcohol.
Ethanol contains how many carbon atoms?
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eth- = 2 carbons; -ol = alcohol.
Putting it together
- Combine the prefix and suffix: prop + ene = propene (3-carbon alkene).
- meth + anol = methanol (1-carbon alcohol).
Worked example. What is "butanol"? But- means 4 carbons; -ol means an alcohol. So butanol is a 4-carbon alcohol. The name decodes the structure.
You've got it
- the prefix gives the carbon count: meth-(1), eth-(2), prop-(3), but-(4)
- the suffix gives the family: -ane, -ene, -ol, -oic acid
- combine them to name (and decode) any compound (e.g. propene = 3-carbon alkene)
Write from pentane having 5 carbons
- The name pentane is given.
- Butane, the lesson example, has 4 carbons. The suffix ene would mean an alkene.
How many carbon atoms are in one pentane molecule?
Pent means five carbon atoms.
How many carbons are in pentane?
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The prefix fixes the carbon count.