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Hi guys and welcome to this new video about how to name organic compounds following aupac rules.

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In this video we're going to focus on branched chain alkanes. If we want to name a branched

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alkane we need to know how to name the branches. The branches are radical which are nothing but

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the molecular compound which comes from a regular hydrocarbon without one hydrogen.

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How can we name it? Firstly, we need to take the name of the regular hydrocarbon. For example, for methane, the radical is going to be CH3. It is what? Methyl. The wood, meth, and the engine, yyl.

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From ethane we have acyl, from propane propyl, from butane butyl or butyl.

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Some radicals have special names which are widely used, partly with the prefix iso.

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It is a muscle radical from a radical chain.

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For example, isopropyl if it has three carbons, isobutyl if it has four carbons, and isopentyl with five carbons. Remember, carbon-1 for any radical is the nearest carbon to the end of the chain.

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Another common prefix is sec, secbutyl, tacbutyl, tacpantyl if they have a tinary carbon atom

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and neopantyl if the tinary carbon atom is in between.

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Finally, with double bones we have benyl and allyl radicals and isopropanol.

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just learn them by heart they are very useful let's try to solve some examples

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we need to identify the longest chain in this case it has eight carbon atoms and

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then we need to identify all the substituents in an ethyl and methyl

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We're going to choose numbering the chain from the

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end that provides the lowest possible log count for the substituent in this

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case 3-meryl-5- ethyl then we're gonna put the name in order using the

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alphabet so 5- ethyl-3-methyl-octane. What happens if there are many

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if the same radicals appear many times, we can use Greek prefixes to indicate the number of

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equal substituents. We have here three, three, five, seven, seven, meta, penta, mthil, decade.

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Here we have some examples. Let's identify the longest chain and let's try to identify

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the substituents methyl and ethyl.

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Now we're going to compare the lockends that we have in both directions.

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When we start from left to right, methyl is in 4, ethyl is in 6.

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However, when we start from right to left, ethyl is in 4 and methyl is in 6.

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So, we're going to choose from right to left because of the alphabetical order, simply.

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So, for example, six must feel no name.

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In this case, we have a challenging decision to make.

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What is the longest possible chain?

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If we start from left to right and horizontally, one, two, three, four, five, six, seven.

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There are seven carbon atoms. It will start from the branch on the top. One, two, three, four, five, six, seven. Exactly the same number of carbon atoms. Which chain do I choose? The one that has more branches. If they all have exactly the same number of carbon atoms.

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So, the horizontal one. Now let's identify all the branches. Methyl in 2, methyl in 3 and in 5. And then on apropyl in 4. Let's put them all in alphabetical order using prefixes to indicate the 3 methyl groups.

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2, 3, 5 trimethyls for propyl obtained.

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In this case we need to identify the longest chain as well.

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It is the horizontal one with 7 carbon atoms, so hept.

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are two methyl groups in two and five in an isobutyl one in four let's put them

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in alphabetical order four isobutyl two five dimethyl obtain we're gonna try to

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solve a bit more challenging case the first step is to identify the longest

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chain which coincides with the horizontal case it is there are it has

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10 carbon atoms so it is the chain and we're gonna start numbering by numbering

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the main chain by the nearest substituent so from left to right

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because we have the method group identify all the substituents and name

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them individually. Methyl in 2, Propyl in 3, Isobutyl in 4, Ethyl in 7 and Isopropyl in 7.

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Finally, let's try to examine the alphabetical order. For Isobutyl, why? Because iso,

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the prefix iso is not considered, so we will be alphabetizing butyl.

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Then, 4-isobutyl, 7-acyl, 7-isopropyl, 2-macyl, 3-propyl decay.

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Here you can see the three-dimensional model of the molecule we have just named.

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I hope you have enjoyed this video, see you next time, bye.