Functional+groups

Once a hydrogen is removed from an alkane, it changes into an alkyl group. This alkyl group can’t exist on its own and therefore has to bond to another group of atoms called a //functional group//.
 * Functional groups **

Compounds with different functional groups form their own homologous series and have different physical and chemical properties.

Examples of different compounds with different functional groups: //General formula:// R-OH (R represents an alkyl group) //Naming:// The ‘e’ at the end of alkane is replaced by ‘ol’. Eg:  CH 3 OH (methanol) ||  C 2 H 5 OH (ethanol) ||
 * ALCOHOLS **
 * [[image:Methanol.png]]

//General formula:// R-X (where X stands for any halogen i.e. F, Cl, Br, I) //Naming:// ‘Fluoro-‘, ‘Chloro-‘ , ‘Bromo-‘ , ‘iodo-‘ placed in front of the alkane. Eg: 2-chloropropane (CH 2 <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">CHClCH 3 <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">) <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">
 * HALOGENOALKANES **

<span style="font-family: Tahoma,sans-serif; font-size: 14pt;">//General formula:// R-CHO <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">or <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">//Naming:// The ‘e’ at the end of the longest chain alkane is replaced by ‘-al’ <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">Eg: ethanal CH 3 <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">CHO <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">
 * Aldehydes **

<span style="font-family: Tahoma,sans-serif; font-size: 14pt;">//General formula:// R-COR’ <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">or <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">(where R’ represents the same alkyl group as R or a different one) <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">//Naming:// the ‘e’ at the end of the longest chain alkane is replaced by ‘-one’ <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">Eg: Propanone CH 3 <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">COCH 3
 * KETONES **

<span style="font-family: Tahoma,sans-serif; font-size: 14pt;">//General formula:// R-COOH <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">or <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">//Naming:// The ‘e’ on the end o the longest chain alkane is replaced by ‘-oic acid’ <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">Eg: Ethanoic acid CH 3 <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">COOH <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">
 * CARBOXYLIC ACIDS **

<span style="font-family: Tahoma,sans-serif; font-size: 14pt;">General formula: R-COOR’ <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">Eg: Propyl ethanoate (CH 3 <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">COOC 3 <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">H 7 <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">) <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">
 * ESTERS **

AMINES <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">//General formula:// R-NH 2 <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">Eg: Propyl amine (C 3 <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">H 7 <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">NH 2 <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">)

//** Physical properties of compounds with different functional groups **// <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">Alkanes are non-polar and thus have low m.p and b.p and are insoluble in water. <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">However if they are bonded to a functional group that is polar, their physical properties change. <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">The greater the polarity of a functional group the higher the m.p and b.p of the compound and the more soluble it is in water (however the effect of having a polar functional group decreases as the number of carbon atoms in the hydrocarbon chain increases). <span style="font-family: Tahoma,sans-serif; font-size: 14pt;">Volatility is another property of liquid organic compounds. Volatility refers to how readily the liquid evaporates. A volatile liquid has a high vapour pressure and therefore evaporates readily at low temperatures. The longer the carbon chain, the less volatile the liquid is.

By the end of this lesson you should be able to: __**<span style="color: #0000ff; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif;">Next up- Alkenes **__
 * use the IUPAC naming system to name any compound containing upto 6 carbon atoms and one of the functional groups above.
 * deduce the structural formulas of compounds containing upto 6 carbon atoms and one of the functional groups above.
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