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﻿Homologous Series

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Definition: Family of organic compounds containing a particular characteristic group and exhibiting similar chemical properties. Examples: CH3OH methanol CH3CH2CH2OH 1-propanol CH3CH2CH2CH2OH 1-butanol

http://www.tutorvista.com/content/chemistry/chemistry-iii/organic-chemistry/homologous-series.php

 As organic compounds in a homologous series gain more atoms, the boiling and melting points go up because more atoms lead to more Van der Waals forces with other molecules.

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 isomer |ˈīsəmər| noun
 * 1** Chemistry each of two or more compounds with the same formula but a different arrangement of atoms in the molecule and different properties.

Example:   top row from left to right: Hexane, 3-methylpentane, 2,2-dimethylbutane  <span style="font-family: 'Comic Sans MS',cursive;">bottom row from left to right: 4-methylpentane, 2,3-dimethylbutane  <span style="display: block; font-size: 13px; line-height: 17px; margin: 0px; overflow-x: hidden; overflow-y: hidden; padding-bottom: 8px; padding-left: 1px; padding-right: 10px; padding-top: 1px; white-space: normal;"> <span style="display: block; font-size: 13px; line-height: 17px; margin: 0px; overflow-x: hidden; overflow-y: hidden; padding-bottom: 8px; padding-left: 1px; padding-right: 10px; padding-top: 1px; white-space: normal;">

<span style="font-family: 'Comic Sans MS',cursive; font-size: 13px; line-height: 17px;">Straight chain molecules have a higher boiling point than isomers with a branched chain. The reason is that straight chain molecules can line up beside each other more effectively than branched chain molecules and therefore have a higher intermolecular force of attraction.

<span style="font-family: 'Comic Sans MS',cursive; font-size: 13px; line-height: 17px;">[] <span style="display: block; font-size: 13px; line-height: 17px; margin: 0px; overflow-x: hidden; overflow-y: hidden; padding-bottom: 8px; padding-left: 1px; padding-right: 10px; padding-top: 1px; white-space: normal;"> <span style="display: block; font-size: 13px; line-height: 17px; margin: 0px; overflow-x: hidden; overflow-y: hidden; padding-bottom: 8px; padding-left: 1px; padding-right: 10px; padding-top: 1px; white-space: normal;"><span style="font-family: Arial,sans-serif; line-height: normal;">In general, alkanes show a relatively low reactivity, because their C bonds are relatively stable and cannot be easily broken. <span style="display: block; font-family: Arial,sans-serif; font-size: 13px; line-height: normal; margin: 0px; overflow-x: hidden; overflow-y: hidden; padding-bottom: 8px; padding-left: 1px; padding-right: 10px; padding-top: 1px; white-space: normal;">

<span style="display: block ! important; font-family: 'Comic Sans MS',cursive; font-size: 13px; line-height: normal; margin: 0px; overflow: hidden; padding: 1px 10px 8px 1px; white-space: normal;">Complete combustion Complete combustion (given sufficient oxygen) of any hydrocarbon produces carbon dioxide and water. Equations For example, with propane (C3H8), you can balance the carbons and hydrogens as you write the equation down. Your first draft would be:

<span style="display: block; font-family: 'Comic Sans MS',cursive; font-size: 13px; line-height: normal; margin: 0px; overflow-x: hidden; overflow-y: hidden; padding-bottom: 8px; padding-left: 1px; padding-right: 10px; padding-top: 1px; white-space: normal;">Counting the oxygens leads directly to the final version:

<span style="display: block; font-family: 'Comic Sans MS',cursive; font-size: 13px; line-height: normal; margin: 0px; overflow-x: hidden; overflow-y: hidden; padding-bottom: 8px; padding-left: 1px; padding-right: 10px; padding-top: 1px; white-space: normal;">With butane (C4H10), you can again balance the carbons and hydrogens as you write the equation down. <span style="display: block; font-family: 'Comic Sans MS',cursive; font-size: 13px; line-height: normal; margin: 0px; overflow-x: hidden; overflow-y: hidden; padding-bottom: 8px; padding-left: 1px; padding-right: 10px; padding-top: 1px; white-space: normal;">Counting the oxygens leads to a slight problem - with 13 on the right-hand side. The simple trick is to allow yourself to have "six-and-a-half" O2 molecules on the left.

<span style="display: block; font-family: 'Comic Sans MS',cursive; font-size: 13px; line-height: normal; margin: 0px; overflow-x: hidden; overflow-y: hidden; padding-bottom: 8px; padding-left: 1px; padding-right: 10px; padding-top: 1px; white-space: normal;">Incomplete combustion

<span style="display: block; font-family: 'Comic Sans MS',cursive; font-size: 13px; line-height: normal; margin: 0px; overflow-x: hidden; overflow-y: hidden; padding-bottom: 8px; padding-left: 1px; padding-right: 10px; padding-top: 1px; white-space: normal;"> Incomplete combustion (where there isn't enough oxygen present) can lead to the formation of carbon or carbon monoxide. As a simple way of thinking about it, the hydrogen in the hydrocarbon gets the first chance at the oxygen, and the carbon gets whatever is left over! The presence of glowing carbon particles in a flame turns it yellow, and black carbon is often visible in the smoke. Carbon monoxide is produced as a colourless poisonous gas.

<span style="display: block; font-family: 'Comic Sans MS',cursive; font-size: 13px; line-height: normal; margin: 0px; overflow-x: hidden; overflow-y: hidden; padding-bottom: 8px; padding-left: 1px; padding-right: 10px; padding-top: 1px; white-space: normal;">The reactions between alkanes and chlorine or bromine

<span style="display: block; font-family: 'Comic Sans MS',cursive; font-size: 13px; line-height: normal; margin: 0px; overflow-x: hidden; overflow-y: hidden; padding-bottom: 8px; padding-left: 1px; padding-right: 10px; padding-top: 1px; white-space: normal;"> There is no reaction in the dark. In the presence of a flame, the reactions are rather like the fluorine one - producing a mixture of carbon and the hydrogen halide. The violence of the reaction drops considerably as you go from fluorine to chlorine to bromine. The interesting reactions happen in the presence of ultra-violet light (sunlight will do). These are photochemical reactions, and happen at room temperature. We'll look at the reactions with chlorine. The reactions with bromine are similar, but rather slower.

http://www.chemguide.co.uk/organicprops/alkanes/oxygen.html

FREE RADICAL MECHANISM VIDEO:

media type="youtube" key="VIHtLIb-oZo?fs=1" height="385" width="480" <span style="font-family: 'Comic Sans MS',cursive;">STEP 1: INITIATION <span style="font-family: 'Comic Sans MS',cursive;"> -free radicals (substances with unpaired electrons) are generated <span style="font-family: 'Comic Sans MS',cursive;"> -UV light is required to generate free radicals <span style="font-family: 'Comic Sans MS',cursive;"> -Cl-Cl bond breaks homolytically (one electron from the bond goes to one atom while the other one goes to the other atom, thereby dissociating the two atoms. This produces two free radicals) <span style="font-family: 'Comic Sans MS',cursive;"> -Equal distribution of bond electrons=Homolytic fission <span style="font-family: 'Comic Sans MS',cursive;"> Example: Cl+Cl-->2Cl+ (UV above arrow)

<span style="font-family: 'Comic Sans MS',cursive;">STEP 2: PROPAGATION <span style="font-family: 'Comic Sans MS',cursive;"> -chlorine radical reacts with alkane <span style="font-family: 'Comic Sans MS',cursive;"> -alkyl radical is produced <span style="font-family: 'Comic Sans MS',cursive;"> -chlorine radical attacks the H on the C-H of alkane (C-H bond breaks homolytically) <span style="font-family: 'Comic Sans MS',cursive;"> -electrons come from C-H <span style="font-family: 'Comic Sans MS',cursive;"> -H reacts with radical to form HCl

<span class="font-family-Comic_Sans MS font-size-12" style="font-family: Comic Sans; font-size: 12px;"> Alkenes are unsaturated compounds of carbon with hydrogen which contain one or two double bonds between atoms of carbon. They burn to form carbon soot and carbon dioxide and water. They are more reactive than alkanes because of the fact that they contain double bonds.

You can work out the formula of any of them using: **C** **n** **H** **2n**

__Telling the Difference__ You can tell the difference between an alkane and alkene by adding **bromine water** to the substance and giving the tube a shake. When bromine water is added to an **alkane** the solution will turn red-brown (the colour of bromine water) and stay that way on shaking. **Alkenes** however will turn red-brown, but then the colour disappears on shaking, this is because the bromine has reacted with the alkene.

Reactions of Alkenes

1. Combustion - Like all other hydrocarbons, alkenes burn in oxygen to produce carbon dioxide and water vapor. An example of the combustion of an alkene is: <span style="background-color: transparent; color: #000000; display: block; overflow-x: hidden; overflow-y: hidden; text-align: left; text-decoration: none;">C2H4(g) + 3O2(g) > 2CO2(g) + 2H2O(g) Ethene + Oxygen > Carbon Dioxide + Water

2. Hydrogenation - Like all other hydrocarbons, alkenes burn in oxygen to produce carbon dioxide and water vapor. This reaction occurs in the presence of a palladium, platinum or nickel catalyst. Heat is required for this reaction when a nickel catalyst is used. An example of the hydrogenation of an alkene is:

<span style="background-color: transparent; border: medium none; color: #000000; display: block; overflow: hidden; text-align: left; text-decoration: none;">CH2=CH2(g) + H2(g) > CH3-CH3(g) Ethene + Hydrogen > Ethane

3. Halogenation - Halogens react with alkenes forming halogenoalkanes. This reaction can occur without catalysis. <span style="background-color: transparent; border: medium none initial; color: #000000; display: block; overflow-x: hidden; overflow-y: hidden; text-align: left; text-decoration: none;">An example of this reaction is: CH2=CH2(g) + Br2(l) -> BrCH2CH2Br(l) Ethene + Bromine -> Ethylene dibromide 4. Halogenation - Bromine water also reacts and is decolorised by alkenes. However, different products are formed in this reaction. An example of this reaction is: CH2=CH2(g) + Br2(aq) + H2O(l) > BrCH2CH2OH(aq) + HBr(aq)

<span style="background-color: transparent; border: medium none initial; color: #000000; display: block; overflow-x: hidden; overflow-y: hidden; text-align: left; text-decoration: none;"> Ethene + Bromine + Water > 5. Hydration - Water can add across the double bond of the alkenes to form aliphatic alcohols. This hydration reaction is catalysed under a number of different conditions. When ethylene and steam are heated (i.e. at 300o Centigrade) under high pressure (i.e. at 70 atm.) in the presence of a catalyst (i.e. phosphoric acid,, on a silica support), ethanol is formed. An example of this reaction is: **H2C=CH2 + H2O ==> C2H5OH** **Ethene + Water ==> Ethanol**

<span style="background-color: transparent; border: medium none initial; color: #000000; display: block; overflow-x: hidden; overflow-y: hidden; text-align: left; text-decoration: none;"> 6. Polymerization - Polymerization of alkenes occurs when many alkene molecules add together to form one large molecule called a polymer.<span style="background-color: transparent; border: medium none; color: #000000; display: block; overflow: hidden; text-align: left; text-decoration: none;">An example of a polymerization reaction is: nCH2=CH2(g) > -[-CH2-CH2-]-n(s)

<span style="background-color: transparent; border: medium none initial; color: #000000; display: block; overflow-x: hidden; overflow-y: hidden; text-align: left; text-decoration: none;"> Read more at Suite101: [|Chemical Reactions of Alkenes] []   <span style="background-color: transparent; color: #000000; display: block; overflow-x: hidden; overflow-y: hidden; text-align: left; text-decoration: none;"> <span style="background-color: transparent; color: #000000; display: block; overflow-x: hidden; overflow-y: hidden; text-align: left; text-decoration: none;">

Organic Derivatives
i.e. ethanol, 2-methylpropan-2-ol || Hydroxyl (Hydrogen-Oxygen) || R-OH || || Organic compounds containing the group –CHO || The -e at the end of the longest chain alkane is replaced by **-al.** i.e. ethanal, 2-methylpentanal || Carbonyl (Carbon-Oxygen) || R-CHO || || Organic compounds containing a carbonyl group bonded to two alkyl groups || The -e on the end of the longest chain alkane is replaced by **-one.** i.e. propanone, 3-pentanone || Carbonyl (Carbon-Oxygen) || R(CO)R’ where R and R’ are alkyl groups ||
 * || ** Definition ** || ** Naming ** || ** Functional Group ** || ** Formula ** ||
 * ** Alcohol ** || Organic compounds containing an OH group attached to a hydrocarbon || The -e at the end of the alkane is replaced by **-ol**
 * ** Aldehyde **
 * ** Ketone **
 * ** Carboxylic acid **

|| Organic compounds containing a –COOH group || The -e at the end of the longest chain alkane is replaced by **-oic acid.** i.e. methanoic acid, 2,4-dimethylpentanoic acid || Carboxyl (Carbonyl-Hydroxyl) || R-COOH || i.e. 2-chloropropane, bromoethane || Halo (halogen) || R-X (X represents F, Cl, Br or I) || i.e. methylamine, 2-aminopentane || Amino || R-NH 2 || Primary alcohol: the carbon that carries the -OH group is only attached to **one** alkyl group Secondary alcohol: the carbon that carries the -OH group is attached to **two** alkyl groups Tertiary alcohol: the carbon that carries the -OH group is attached to **three** alkyl groups
 * ** Alkyl halide ** || Organic compounds in which halogen atoms have been substituted for hydrogen atoms in an alkane || fluoro-, chloro-, bromo-, or iodo- is placed before the alkane
 * ** Amine ** || Organic compounds that contain a basic nitrogen atom with a lone pair || Prefix ** (amino-) ** or suffix ** (-amine) **before or after the alkyl group.

Alcohol + Oxygen --> Carbon dioxide + Water R-OH + O2 --> CO2 + H2O
 * Combustion of Alcohols**

Primary: RCH2-OH + O --> RCH-O + H2O Secondary: RCH-OH + O --> RC-O + H2O Tertiary: No reaction
 * Oxidation of Alcohols**

<span style="font-family: Helvetica,Arial; font-size: medium; font-weight: normal; line-height: normal;">In a substitution reaction, the halogen atom is replaced by an -OH group to give an alcohol.
 * Substitution Reactions of Halogenoalkanes with Sodium hydroxide**



[] http://wiki.answers.com/Q/What_is_the_chemical_formula_for_an_aldehyde http://www.chemguide.co.uk/basicorg/conventions/names.html#top http://www.chemguide.co.uk/organicprops/carbonyls/background.html http://www.answers.com/topic/ketone http://www.chemguide.co.uk/organicprops/acids/background.html http://dl.clackamas.cc.or.us/ch106-04/nomencla.htm http://wiki.answers.com/Q/What_is_the_general_formula_for_carboxylic_acid