Hydrocarbons Chemistry PDF

Here is the converted text from the image to a structured markdown format: ```markdown 15M Amit Patil ## + HYDROCARBONS\* Hydrocarbons are organic compounds containing carbon and hydrogen only. **Classification**- On the basis of their structure, hydrocarbons are mainly classified as two types:...

Here is the converted text from the image to a structured markdown format: ```markdown 15M Amit Patil ## + HYDROCARBONS\* Hydrocarbons are organic compounds containing carbon and hydrogen only. **Classification**- On the basis of their structure, hydrocarbons are mainly classified as two types: * Aliphatic Hydrocarbon * Saturated hydrocarbon * Alkanes ($C_nH_{2n+2}$) * $C_2H_6$ - Ethane * $C_3H_8$ - Propane * Unsaturated hydrocarbon * Alkenes ($C_nH_{2n}$) * $C_2H_4$- Ethene * $C_3H_6$ - Propene * Alkynes ($C_nH_{2n-2}$) * $C_2H_2$ - Ethyne * $C_3H_4$ - Propyne * Alicyclic or Carpocyclic Hydrocarbons * Cycloalkanes ($C_nH_{2n}$) * Aromatic Hydrocarbons ($C_nH_{2n-6}$) *Aliphatic Hydrocarbons* - (acyclic or open chain hydrocarbons) In this type of compounds, the carbon atoms are arranged in a straight or branched chain. *Saturated hydrocarbons* - The Carbon atoms are linked by single sigma (𝛔) bonds- are called saturated hydrocarbons/paraffins. All the Carbon atoms in these molecules are tetrahedral and are $sp^3$ hybridized. Q.NO.I - 2,14,2015 ⇒ 1M 2. NO:- 2.20 ⇒ 1M Q.29 ⇒ IM Q.NO: Q.43.43 = SM --- *Alkanes* Alkanes are saturated open chain hydrocarbons. These are called paraffins because of their least toward chemical reactions. They contain two types of covalent bonds i.e. C–C and C–H In alkanes, each carbon atom is $sp^3$ hybridized and consists of four strong 𝜎 bonds. Petroleum and natural gas are the main source of alkanes Methods of preparation of alkanes ⇒ *From unsaturated hydrocarbons* When alkenes or alkynes are heated with hydrogen in the presence of nickel, platinum, or palladium catalysts, at 500k alkanes are formed. The process of addition of hydrogen to an unsaturated hydrocarbon in the presence of catalyst is called catalytic hydrogenation. $CH_2=CH_2 + H_2 \xrightarrow{Ni} CH_3-CH_3$ Ethyne Ethane $CH_3-CH=CH_2 + H_2 \xrightarrow{Ni} CH_3-CH_2-CH_3$ Propene Propane --- *From Alkyl Halides* When haloalkanes (except fluorides) are reduced with hydrogen in the presence of heated nickel or palladium at 528k, alkanes are formed. Zinc catalyst. $R-X +2(H) -> RH + HX$ $CH_3-Cl+2(H) \xrightarrow{Zn+HCl} CH_3 + HBr$ Chloromethane Methane $C_2H_5 Cl + 2(H) \xrightarrow{Zn+HCl} C_2H_6$ Ethyl chloride Ethane *Wurtz Reaction* - When two molecules of alkyl halides react with sodium in dry ether, higher alkanes are formed. $R-X + 2Na + X-R \xrightarrow{Dry Ether} R-R + 2NaX$ * When methyl bromide is heated with sodium in dry ether medium, then ethane is formed. $2CH_3 Br + 2Na \xrightarrow{Dry Ether} CH_3-CH_3 + 2NaBr$ * When a mixture of two different alkyl halides is heated with sodium metal in dry ether, three alkanes are preformed (this reaction follows a radical path). * $CH_3-Br+2Na+BrCH_2CH_3-> CH+2NaBr$ Bromo ethane + $CH_3CH_2CH_3$ *From Carboxylic acid* Sodium salt of carboxylic acids on heating with Soda-Lime. (mix. of $NaOH$ and $CaO$) gives alkanes containing one carbon atom less than carboxylic acid. $CH_3COONa +NaOH \xrightarrow{CaO} CH_4+ Na_2CO_3$ Sodium acetate- Methane $C_3CH_3 COONG +NaOH Cao C_2H_5 + Na_2CO_3$ *Physical properties* * Alkanes are nonpolar molecules insoluble in water but are soluble in nonpolar solvents. * First four members are gases, next $C_5-C_{17}$ are liquids and $C_{18}$ onwards are solids. * B.P. of alkanes increases with an increase in the number of carbon atoms (Increase of 20-30 with addition of each $-CH_2$ unit) * B.P. of alkanes decreases with an increase in branching. * *Chemical reactions* - Alkanes are the saturated compounds and can undergo substitution reactions. One or more hydrogen atoms of alkanes can be replaced by halogen, nitro group, sulfonic acid. These reactions, in which hydrogen atoms of alkanes are substituted, and are therefore reaction. --- *Substitution of halogen atom in the place of hydrogem in call halogenation* E.g. chlorination of methane When methan react with chlorine is the presence of diffused sunlight. replacement of hydrogen atoms of methane takes place, forming methyl chloride, methylene chloride. Chloro form and carbon tetrachloride. $ CH_4 + cl_2 \text{sun light} CH_2+HCl$ methyl chloride +$CH_2 + Cl_3 CH Cl_5+HCl$ $CH_{cl3}+cl_2 + CH_4+Hcl$ $Cal₄ + Hcl$ 4 . Reactions with steam methaueo react with an steam at 1272K the presence of nichel Catalyst to form carbone monixide aud di hydragen. $CH_4H_2D$ &controlled oxidation. 4. alhaues on hating with limited supply of direygen or ais anhigh pressure in the prescu $ 2CH_4+2+42778484 Methanol Com bus tion: - Alkanes on healing of diraygon, aire completely goxidized de carbon dionde A- and wate with the evaluation og Lange amount at head. 9M64120,5)-43-20 DH -470kgmot" The general Comportion op ay olcane is" Entranter (3일)어일-60371277340. --- Mechanism 7 Chlorination de methame chanism - Chlorinationy methane lake place 47 fee radical the mechaism involves 46 following. 1 step- chain initiationy- Chlorine molecule abronte energy - sun light and undergo homoly" firsion giving chlorin the radical. " step = chain propagation." Chlorine from radical outtacks methane nolecule gives giving Hel and methyl foe radicals CH3 +442H CI+Cy 449 mee-radical famd atlacks are morele chlorune giving methyl chloride and chlorine feee --- methyl towe & radicial repeats 449, and hence the chain This step. @aud step.5 propagato. 8224 the chain. step I Termination -wken highly readive free radicalsreact and themsleves forming Stable molecules. **Akeny: 14/1** Akenes are 48 path and, Carbon contains at Least one Cartion- Carbon doubtebonde Alkane have general pomular cufhan Methode I preb" deation des Albene: **p-l** prom alkynt - The poudral reduction - Allumes - With Amm hydrogen .7" -e - ---