Organic Chemistry Hydrocarbon

1-In 1806, the scientist Berzelius divided all compounds into two categories: a- Organic compounds: They are compounds that extracted from animal or plant origin. b- Inorganic compounds: They are compounds originate from mineral sources in earth. 2-Vital Force theory: Brezelius considered that organic compounds are formed by vital force which is found in living cells of the body and it is impossible to synthesized them in laboratories. 3-In 1828, The German scientistWohler destroyed the vital force theory, when he prepared urea by heating an aqueous solution of two inorganic compounds, ammonium chloride and silver cyanate. 4-Organic chemistry focused on the study of carbon element with exception of carbon oxides, carbonate and cyanides salt. 5- The number of organic compounds are more than the organic ones. The ratio between the organic and inorganic compounds is approximately 20 : 1 . 6-The abundance of organic compounds is due to the ability of carbon atom to combine with itself or with others atoms by different kinds of bond, it might connect through single, double, triple bonds. 7-Carbon atoms can join together with different methods, either straight chains, branched chains, homocyclic or heterocyclic. 9- Molecular Formula: It is the formula which indicates the number and kind of the elements which form the chemical compound, and doesn't show the kind of the linkage between the atoms in the molecule. 10-Structural Formula: It's the formula which indicates the number and kind of each element in the molecule, and the kind of linkage between the atoms by the covalent bonds. 11-The number of covalent bonds around the atom indicates its valancy .Each single covalent bond represents one pair of valency. 12-Isomerism: many organic compounds are different in the physical and chemical properties and also in structural formula but they have the same molecular formula. 13- The structural formula show that the molecule has a stereostructure shape i.e. its atoms are directed in the three dimensions. 14- Detection of carbon and hydrogen in organic compounds: 1-The white colour of anhydrous copper sulphate turns into blue which indicates the absorption of (CuSO4) to water vapour which is formed from combination of oxygen of CuO with the hydrogen of organic compound. 2-Lime water turns turbid due to the evolution of carbon dioxide (CO₂), which is formed from combination of oxygen of (CuO) with the carbon of the organic compound. Conclusion:The organic compound contains carbon and hydrogen. 15- Hydrocarbons are organic compounds consist of carbon and hydrogen only. 16- Alkanes (C_nH_2n+2)saturated aliphatic open chain hydrocarbons .The carbon atoms are combined together by a single bond called sigma bond which is strong and difficult to be broken therefore they are relatively chemically inactive. 17- Each alkane compound exceeds the previous one by (-CH₂) group. 18-Members of alkanes are ended by the suffix (ane) which indicates that the compound is belonging to (alkanes chain) , The prefix of the name indicates the number of carbon atoms in the molecule . For example the prefix Meth = 1 , Eth = 2 , Prop = 3 , But = 4 , Pent =5 and so on . Alkanes form a homologous series. 19-Homologous series: It is a group of compounds that having the same molecular formula , chemical properties and graduated physical properties. 20-Alkanes have a very important role as a fuel, as natural gas which is used now as fuel in homes. 21- The Alkyl Radical (R -) :It is an organic atomic group which does not found alone. It is derived from the corresponding alkane by removing one hydrogen atom .Alkyl radicals are given the symbol "R".Their general formula is (C_nH_2n+1).Its name is derived from the corresponding alkane by replacing the suffix (ane) by (yl). 22- The nomenclature of alkanes: (IUPAC system) International Union of Pure and Applied Chemistry. 23-The nomenclature of alkanes by the IUPAC system may be summarized as follows: 1-The name of the hydrocarbon is determined according to the longest continuous carbon chain . 2-The carbon atoms are given numbers in the longest chain. 3- If the longest hydrocarbon chain free from any branches or side chain the carbon atoms are given numbers from any side (left or right side). 4-If the longest hydrocarbon chain attached to an alkyl group or any other atoms. The numbering of carbon atoms in the hydrocarbon chain begins from the side which is nearer to the branch. The nomenclature begins by the number of the carbon atom from which the chain arises, then the name of the branch, and ending by the name of the alkane. If the side group is repeated in the hydrocarbon chain we use prefix Di - or Tri - or Tetra - to indicate the number of repetition. 1-If the branch is a (-ve) group such as. Cl ^- , Br ^- or NO₂ ^- , the name of this group is ended by the letter (O) so we say chloro , bromo or nitro. 2-If the side groups are different (alkyl group and halogens). the groups are arranged according to their alphabetical Latin names. 24-Methane can be prepared in lab. by dry distillation of anhydrous sodium acetate with soda lime 25- Soda lime is a mixture of Na OH and quick lime CaO which doesn't take part in the reaction but it helps in reducing the melting points of the reaction mixture . 26-The first four members of alkanes are gases in normal temperature. Alkanes ,which contain from [5-17] carbon atoms are liquids e.g gasoline and kerosine which are used as liquid fuel .The compounds which contain more than 17 carbon atoms are solids e.g. paraffin wax. 27-Alkanes are non polar compounds insoluble in water, so the metals are covered by heavy alkanes to protect them against rust and corrosion. 28-The carbon atoms in alkanes are combined together by the strong sigma bonds , These bonds cannot be broken easily except under certain conditions, Therefore, alkanes are comparatively, inactive compounds. 29 -All alkanes burn giving water vapour and carbon dioxide, these reactions are highly exothermic, that is 30-The reactions with Halogens: a. In direct sunlight : If methane reacts with chlorine or fluorine in the direct sun light, the halogen eliminates hydrogen from methane and black carbon is remained . The reaction is accompanied by explosion ( this reaction is called elimination reaction 31-In indirect sunlight : Alkanes react with halogens in indirect sun light in a series of substitution reactions these are : 32- Chloroform was used for a long time as anesthetic substance but its uses stopped because the inaccurate estimation of the dose for each patient causes the death. Halothane is used now as anesthetic substance with safety and its formula CHBrCl - CF₃ 33-The compound 1,1,1 trichloro ethane is used in the dry cleaning. 34-Freons were used in air conditions and fridges, also as a rushed substance to liquid and perfumes and as a cleaner of electronic sets. 35-Freons are consider as halogenated derivative of alkanes as CF₄ tetra flouro methane but the famous one is dichloro, diflouromethane CF₂ Cl₂ or1-bromo 1-chloro-2,2,2 triflouroethane . Freons are used by large quantities due to its sheep price, easily to be liquefied, non poisonous and non corrosive for metals, however Freon's cause the decay of the ozone layer which protect the earth against harmful effect of ultra violet rays . 36.Thermal catalytic cracking: heating the heavy petroleum products under high pressure and temperature in the presence of a catalyst to produce two kind of products. This process usually takes place during the refining of petroleum oil to convert the heavy long petroleum chains to the daily used lighter short chain products . 37-Methane is used to obtain finely divided carbon, (black carbon ).The black carbon is produced by heating methane to 1000?C in the absence of air. Black carbon is used in the manufacture of car tiers, black painting, polishes, and printing ink . 38- Methane is used to obtain to obtain " water gas".water gas is a mixture of hydrogen and carbon monoxide which is used as reducing agent or as a flammable fuel.