Prop- prefix

Names.—The names of the different hydrocarbons are similar and are in harmony with the idea of an homologous series. The common termination ane is given to all and, above the fourth member, a Greek numerical prefix indicates the number of carbon atoms in the molecule. The five-carbon compound is pent-ane, the six carbon hex-ane, etc. The first four members have special non-numerical prefixes as methane, eth-ane, prop-ane and but-ane. Similarly the radicals of each hydrocarbon simply take the termination yl in place of ane, thus, but-yl, pent-yl, hex-yl, etc. 

The first thing that you want to do is determine the molecular formula for the compound. The prefix prop- tells us (see Figure 4 fh) that we are dealing with a compound that contains three carbon atoms. The suffix -ene tells us that we are dealing with an alkene. Alkenes contain twice as many hydrogen atoms as carbon atoms, so propene must have six hydrogen atoms (2x3 = 6). 

There are other alkyne compounds, but they do not have much commercial value, and will not be commonly encountered. A three-carbon compound with one triple bond has prop as a prefix for three carbons and is called propyne, with a molecular formula of C3H4 It is listed in the Condensed Chemical Dictionary as propyne, but you are referred to methylacetylene for information. It is listed as a dangerous fire risk, and it is toxic by inhalation. Propyne is used as a specialty fuel and as a chemical intermediate. A four-carbon alkyne has the prefix but, and the compound is called butyne, with the molecular formula of C4H6. The chemical listing is under the name ethylacetylene, and it is designated as a dangerous fire risk. It is also used as a specialty fuel and as a chemical intermediate. The following shows the structures for ethyne, propyne, and butyne ... 

The name of each of the members of the hydrocarbon classes has two parts. The first part, the prefix—meth-, eth-, prop-, but-, and so on—reflects the number of carbon atoms. When more than four carbons are present, the Greek or Latin number prefixes are used penP, hex-, kept-, oct-, non-, and dec-. The second part of the name, or the suffix, teUs the class of hydrocarbon. Alkanes have carbon-carbon single bonds, alkenes have carbon-carbon double bonds, and alkynes have carbon-carbon triple bonds and are indicated by the suffixes -ane, -ene, and -yne, respectively. 

First look at the first few letters of the name (meth, eth, prop, but, etc.). This is the prefix that tells the number of carbons in the parent chain. Next look at "an," "en," or "yn." These infixes indicate the nature of the carbon-carbon bonds in the parent chain.The letters that follow the infix are part of the suffix, which determines the class of compound to which the molecule belongs. 

The International Union of Pure and Applied Chemistry (lUPAC) method of naming alkanes is fairly simple. The names of all alkanes end in one. The prefixes, based on the number of carbons in the molecule, make naming a lot like counting. Meth- (1 carbon), eth- (2), prop- (3), but- (4), pent- (5), hex-(6), hep- (7), oct- (8), non- (9), and dec- (10) are the basic prefixes. If you know these, you will be able to breeze through naming. 

Latin word for a given number, but there are exceptions. A one-carbon unit has the prefix meth, two carbons are eth, three carbons are prop, four carbons are but, and five, six, seven, eight, nine, and ten carbons are derived from the Latin terms pent, hex, hept, oct, non, and dec, respectively. 

Indicate the prefix that is used for the molecule (CH3)2CH(CH2)2CH20H meth, eth, prop, but, pent, or hex. 

As mentioned already, alcohols are compounds that have a hydroxyl group (-OH) attached to a carbon atom. The most common alcohols are alkanes that have an oxygen atom inserted between one of the carbon atoms and a hydrogen atom. There are thousands, if not milUons, of alcohols. However, the alcohols people encounter most frequently are methanol, or methyl alcohol (CH3OH) ethanol, or ethyl alcohol (CHjCHjOH) and isopropyl alcohol (CjH OH). In fact, most people just use the word alcohol for any alcoholic beverage instead of the correct name, ethyl alcohol, but everyone knows what they mean. By the way, be sure to note the continued use of the prefixes meth, or methyl, for one carbon eth, or ethyl, for two carbons and prop, or propyl, for three carbons. 

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