what is the valence of carbon in organic compounds;
how saturated hydrocarbons are built;
how to draw a structural formula of a given hydrocarbon;
how to create hydrocarbon’ names.
You will learn
what alcohols are;
to write down molecular and structural formulas of simple alcohols;
to recognize formulas of alcohols based on the functional group.
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Hydrocarbon derivatives
Alcohols are derivatives of hydrocarbon where carbon atom (or atoms) was (were) replaced with hydroxyl functional group , so‑called hydroxyl group (hydrogenium is the Latin name of hydrogen, oksygenium – of oxygen). If one hydrogen atom in an alkane molecule is replaced with one hydroxyl group, then a compound consisting of a hydrocarbon chain () and alcohol functional group is formed.
Task 1
Watch presentation. Memorize how alcohol formulas are created.
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Formula of monohydric alcohol is:
Alcohol names can consist of one or two parts.
Alcohols containing one hydroxyl group in the molecule, like hydrocarbons, form a homologous series. The name of an alcohol derived from an alkane is formed from the name of an alkane with the same number of carbon atoms in the molecule, adding to it the ending -ol and removing the ending -e, e.g. methanol is a methane derivative, ethanol – an ethane derivative. Names of alcohols consisting of two parts are formed by adding the name derived from particular hydrocarbon to the ‘alcohol’, changing the ending -ane into -yl, e.g. methyl alcohol.
General formula of monohydric alcohol is formed by replacing one hydrogen atom by hydroxyl functional group in alkanes.
The table contains alcohols ranked according to the increasing number of carbon atoms. Each of the following compounds differs from the previous one by group . This series is called the homologous seriesalcohol homologous serieshomologous series.
Name of alcohol
Formulas
methanol (methyl alcohol)
etahnol (ethyl alcohol)
propan–1–ol (propyl alcohol)
butan–1–ol (butyl alcohol)
Exercise 1
The hydroxyl group may be attached to different carbon atoms. Determine butanol formulas on the basis of a general formula of monohydric alcohols derived from alkanes.
In monohydric alcohol molecules the hydroxyl group can be attached to various atoms of carbon. This phenomenon is called position isomerism. The number contained in the alcohol name indicates the number of the carbon atom where the group is located.
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Methyl alcohol
Alcohol with the simplest structure derives from methane, which means that its molecule contains only one carbon atom. One hydrogen atom in methane is replaced by functional groupfunctional groupfunctional group. Due to the number of groups, it is a monohydric alcohol. Methanol is a methane derivative.
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Ethyl alcohol
The process of alcohol fermentation occurs under the influence of a special yeast species found in the peels of ripe grapes (or other fruits). Glucose – sugar contained in fruit juice – under favourable conditions, undergoes a chemical reaction where ethyl alcoholalcoholsalcohol is produced.
Reaction equation – in words:
Reaction equation – molecular form:
The reaction equation shows that alcohol fermentationalcohol fermentationalcohol fermentation is a process that takes place under the influence of yeast. Its products are ethyl alcohol and carbon dioxide.
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Ethyl alcohol contains as many carbon and hydrogen atoms as ethane. Due to this similarity of composition, ethanol is one of ethane derivatives.
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Based on the position of carbon in the periodic table, we can conclude that the atom of this element has four valence electrons. Thus, it can create up to four bonds in organic compounds. In the ethyl alcohol molecule, the carbon atoms are connected with each other by a single bond. The oxygen atom forms two bonds: one with a hydrogen atom and one with a carbon atom. Each of the hydrogen atoms is monovalent, i.e. it creates only one bond.
Molecular formula of alcohol does not inform how the molecule is build. Thus, to determine differences in structure of various of alcohols, structural forms are used.
Ethanol formula:
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Exercise 2
Assign appropriate names to formulas of alcohol methanol,
butyl alcohol, propanol, ethyl alcohol, pentanol. Możliwe odpowiedzi: ce ha trzy o ha, ce cztery ha dziesięć o, ce trzy ha osiem o, ce dwa ha sześć o, ce pięć ha dwanaście o.
Assign appropriate names to formulas of alcohol methanol,
butyl alcohol, propanol, ethyl alcohol, pentanol. Możliwe odpowiedzi: ce ha trzy o ha, ce cztery ha dziesięć o, ce trzy ha osiem o, ce dwa ha sześć o, ce pięć ha dwanaście o.
alkohole – pochodne węglowodorów, w których co najmniej jeden atom wodoru zastąpiono grupą hydroksylową
alcohol fermentation
alcohol fermentation
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fermentacja alkoholowa – przemiana glukozy pod wpływem enzymów wytwarzanych przez drożdże; jej produktami są alkohol etylowy i tlenek węgla(IV)
functional group
functional group
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grupa funkcyjna – grupa atomów (lub atom) połączona z łańcuchem węglowym w węglowodorach; jej obecność decyduje o przynależności do danej grupy związków organicznych
alcohol homologous series
alcohol homologous series
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szereg homologiczny alkoholi – szereg alkoholi uporządkowanych według wzrastającej liczby atomów węgla w cząsteczce; dwa kolejne związki różnią się od siebie o grupę atomów