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HALOALKANES AND HALOARENES in 1 Shot: All Concept & PYQs Covered | Class 12th Boards | NCERT

NCERT Wallah・2 minutes read

The first live organic chemistry class discussed the topic of Halo Alkane and Halo Aris, emphasizing understanding chapters and scoring well in exams. The text explained the basics of organic chemistry, providing examples for different compounds and highlighting the importance of naming conventions and the classification of compounds based on the number of halogen atoms present.

Insights

  • Understanding the chapters and scoring well in exams are key emphases of the class on organic chemistry.
  • The process of replacing hydrogen atoms in alkane and aromatic hydrocarbons with halogens to form hello alkane and hello arin compounds is explained.
  • The text provides detailed instructions on naming conventions for chemical compounds, highlighting the importance of proper numbering and prioritization in naming compounds with double bonds and halogens.
  • Practical examples and exercises are utilized to reinforce the understanding of naming conventions for chemical compounds and the concept of isomerism.
  • Different reactions, such as the Finkelstein and Swarts reactions, are detailed for the synthesis of alkyl iodides from alkyl halides, showcasing practical applications in organic chemistry.
  • Physical properties of alkyl halides and aryl halides, including solubility and boiling points, are discussed, emphasizing the impact of molecular mass and branching on these properties.

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Recent questions

  • What is the importance of understanding organic chemistry?

    Understanding organic chemistry is crucial for students to excel in exams and grasp fundamental concepts. It involves learning about classification, nomenclature, and preparation methods of organic compounds. Knowing the general formula of alkanes and the halogen family in the periodic table is essential. The process of replacing hydrogen atoms with halogens to form haloalkanes and haloarenes is a key concept. Naming conventions for these compounds, such as alkyl halides and aryl halides, are also significant. Active participation in classes and note-taking aids in better comprehension and retention of material.

  • How are haloalkanes and haloarenes classified?

    Haloalkanes and haloarenes are classified based on the number of halogen atoms present in the compound. They can be categorized as mono, di, or poly haloalkanes and haloarenes. Examples like chloroethanol, dibromobenzene, and polyhaloalkanes showcase these classifications. Compounds with more than two halogen atoms are termed trimers or tetramers in the polyhaloalkane category. Similarly, polyhaloarenes are classified based on the number of halogens they contain. Understanding these classifications is essential in organic chemistry.

  • What are gemin dihalides and vicinal dihalides?

    Gemin dihalides have two identical halogens on the same carbon atom, also known as alkyl halides. On the other hand, vicinal dihalides have two identical halogens on adjacent carbon atoms, referred to as alkenes. Examples like neodichloroethane and ethylidene chloride illustrate these concepts. Recognizing the differences between gemin and vicinal dihalides is crucial in understanding the naming and properties of organic compounds.

  • How are alkyl halides classified?

    Alkyl halides are classified as primary, secondary, or allyl based on the number of carbon neighbors they have. The carbon atom is sp3 hybridized with a halogen attached to it. Understanding the classification of alkyl halides based on their carbon structure is essential in organic chemistry. Differentiating between primary, secondary, and allyl alkyl halides aids in predicting their reactivity and properties.

  • What are the key factors affecting the strength of carbon-halogen bonds?

    The strength of carbon-halogen bonds varies depending on the halogen present and the type of compound. For example, the carbon-iodine bond is the weakest, requiring the least energy to break, while the carbon-fluorine bond is the strongest due to its short length. Factors like bond length and bond dissociation energy influence the strength of carbon-halogen bonds. Understanding these factors is crucial in predicting the reactivity and stability of organic compounds.

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Summary

00:00

"Introduction to Organic Chemistry: Halo Compounds"

  • The text is a conversation introducing the first live class on organic chemistry, focusing on the topic of Halo Alkane and Halo Aris.
  • The class emphasizes the importance of understanding the chapters and scoring well in exams.
  • The discussion covers the basics of organic chemistry, including classification, nomenclature, and methods of preparation.
  • Specific examples are provided for mono, di, and poly hello alkane and hello arin compounds.
  • The importance of knowing the general formula of alkanes and the halogen family in the periodic table is highlighted.
  • The process of replacing hydrogen atoms in alkane and aromatic hydrocarbons with halogens to form hello alkane and hello arin compounds is explained.
  • The text delves into the naming conventions for these compounds, such as alkyne halide and aryl halide.
  • Classification of compounds based on the number of halogen atoms present is discussed, leading to mono, di, and poly hello alkane and hello arin categories.
  • Examples are provided for each classification, showcasing compounds like chloroethanol, dibromo benzene, and poly haloalkanes.
  • The text concludes with a call for active participation in the class and encourages note-taking for better understanding and retention of the material.

18:35

"Polyhaloalkanes and Polyhaloarenes Classification"

  • Chloroform is CHBr3, bromoform is CCl4, and carbon tetrachloride is CCl4.
  • Polyhaloalkanes can have more than two halogen atoms, classified as trimers or tetramers.
  • Polyhaloarenes are based on the number of halogens present.
  • Gemin dihalides have two identical halogens on the same carbon atom.
  • Vicinal dihalides have two identical halogens on adjacent carbon atoms.
  • Gemin dihalides are also known as alkyne halides, while vicinal dihalides are known as alkenes.
  • Neo dichloroethane is the IUPAC name for a compound with two chlorine atoms on the same carbon.
  • Ethylidene chloride is the common name for a compound with two carbons and a chlorine atom.
  • Neo dichloroethane is an example of a gemin dihalide, while ethene dichloride is an example of a vicinal dihalide.
  • Alkyl halides are classified as primary, secondary, or allyl based on the number of carbon neighbors.

40:10

"Hybridized Carbon Bonds in Organic Compounds"

  • Carbon is sp3 hybridized with a halogen on it.
  • Discussion on the similarity between c double bond c and benzylic.
  • Classification of beta compounds with sp2 sp2 carbon halogen bond.
  • Differentiation between vinyl halide and aryl halides.
  • Explanation of vinylic carbon being sp2 hybridized.
  • Clarification on halogen presence on vinyl carbon.
  • Distinction between halogen directly on benzene ring and aryl halide.
  • Detailed explanation of nomenclature rules in organic compounds.
  • Clarification on the naming process for compounds with halogens.
  • Importance of correct numbering and prioritization of double bonds over halogens in naming compounds.

01:01:05

Naming Compounds: Double Bonds and Halogens

  • Double bond formation and numbering errors were discussed, emphasizing the importance of correct prioritization.
  • The naming process for compounds with double bonds and halogens was detailed, highlighting the significance of proper numbering.
  • Instructions were given on how to name compounds based on the positioning of double bonds and halogens.
  • The relationship between bromine positions in compounds and the naming conventions for such compounds was explained.
  • The process of determining the positions of bromine in relation to each other in compounds was outlined.
  • The significance of correct numbering and prioritization in naming compounds with double bonds and halogens was reiterated.
  • Practical examples and exercises were provided to reinforce the understanding of naming conventions for chemical compounds.
  • Detailed instructions were given on how to structure and name compounds based on the positions of functional groups and substituents.
  • The concept of isomerism in chemical compounds, specifically focusing on structural isomerism, was introduced.
  • Practical examples and exercises were used to illustrate the concept of isomerism and the importance of correct naming and structural understanding in chemistry.

01:25:15

"Eight C5H11Br Isomers: IUPAC Names Revealed"

  • Eight isomers of C5H11Br are formed in the question.
  • The structure of the eight isomers is created, and their IUPAC names are written.
  • The carbon chain is kept once, with bromine placed on the first, second, and third carbons.
  • The IUPAC names of the three isomers are given, classified into two degrees.
  • The carbon chain of five is maintained, with three possibilities for bromine placement.
  • Isomers are created with bromine on the first, second, and third carbons, classified into first and second degrees.
  • A chain of four is used, with methyl placed on the first, second, and third carbons.
  • The names of the isomers with bromine and methyl are given alphabetically and classified into beta degrees.
  • The eighth isomer has a chain of three with two methyl branches.
  • The names and degrees of the last isomer are provided, with primary carbon neighbors indicated.

01:46:06

Bond Length and Energy in Chemical Reactions

  • Bond length is inversely proportional to bond dissociation energy (BD beta bond).
  • The longest carbon-iodine bond is 214 pico meters, requiring the least energy to break.
  • The carbon-iodine bond is the weakest, while the carbon-fluorine bond is the strongest due to its short length.
  • The Dapor moment of CH3Cl is the highest at 1.86d, followed by CH3F, CH3Br, and CH3.
  • The Debye unit is used to measure the moment, similar to length.
  • The carbon-halogen bond strength is highest in CH3F due to its short bond length.
  • The Lucas test is used to distinguish primary, secondary, and tertiary alcohols based on turbidity.
  • Alcohol reacts with concentrated HCl and hydrous zinc chloride to form alkyl halides.
  • Other methods involve reactions with sodium bromide, PCl5, PCl3, and thionyl chloride to produce alkyl halides.
  • Hydrocarbons can be obtained from alkanes through free radical substitution reactions with halogens like fluorine, chlorine, bromine, and iodine.

02:23:51

Alkane Chlorination and Halogen Exchange Reactions

  • Chlorination of methane in the presence of sunlight generates chloromethane (CH3Cl) through substitution of hydrogen with chlorine.
  • Different types of carbon identification are based on the presence of hydrogen on carbon atoms, leading to primary and secondary carbon distinctions.
  • The substitution of hydrogen on primary and secondary carbons in alkane results in the formation of different products, such as chloropropane or n-propyl chloride.
  • The number of products in monochlorination reactions depends on the types of carbon present, with two different carbons yielding two products like one bromobutane and one 2-bromobutane.
  • The mechanism of alkane reactions involves the addition of molecules to unsymmetrical alkenes, following the Marconic rule for the distribution of negative and positive parts.
  • Vicinal dihalides are formed from unsymmetrical alkenes through the addition of molecules like bromine or iodine, adhering to the rule that two same halogens are adjacent to carbon atoms.
  • The reaction of unsymmetrical alkenes with chlorine or bromine at high temperatures leads to substitution reactions where hydrogen is replaced by halogens.
  • Halogen exchange reactions, such as the Finkelstein and Swarts reactions, are utilized to convert alkyl halides into iodides through the exchange of halogens in the presence of specific reagents like sodium iodide and acetone.
  • The Finkelstein reaction involves the halogen exchange of alkyl halides to form iodides, while the Swarts reaction achieves the same result using different conditions.
  • These reactions provide efficient methods for the synthesis of alkyl iodides from alkyl halides, offering practical applications in organic chemistry.

02:45:55

"Reactions and Synthesis of Halogen Derivatives"

  • The text discusses the conversion of ch3f to ch3ch2f and the creation of AC silver chloride.
  • It mentions the use of AA as a fluorinating agent and alternative options like hg2f2, cof2, or sbf3.
  • Different reactions for halogenation of alkynes are explained, including the exchange of agf2 with f2, cof2, or sbf3.
  • The Finkelstein and Swarts reactions are detailed for making alkyl iodides and alkyl fluorides, highlighting the differences in their applications.
  • The text delves into the reactions involving silver salts and carbosynth stickers, emphasizing the formation of alkyl bromides and bromo methane.
  • It discusses the use of sulfuric acid in reactions involving alcohols and potassium, explaining the reasons for choosing specific acids for different reactions.
  • The text explores the formation of halogen derivatives of propane and isomeric alkane c5a1, detailing the process of monochlorination and the creation of different isomers.
  • It explains the concept of electrophilic substitution reactions in benzene, detailing the generation of electrophiles and the ortho-para directing nature of the reactions.
  • The text discusses the electrophilic substitution of toluene or methyl benzene, highlighting the generation of electrophiles and the ortho-para directing nature of the reactions.
  • Lastly, the text introduces the formation of benzene diiso rule salts through the reaction of benzene with concentrated nitric acid and sulfuric acid, explaining the process of creating these salts.

03:09:28

"Chemical Reactions in Organic Chemistry"

  • Nitro benzene undergoes reduction with metal in the presence of acid to produce aniline.
  • Aniline is further reacted with nano2+ hclo2 at 5 degrees celsius to generate benzene dizone chloride.
  • The process involves the generation of nitrous acid and the formation of c2.
  • Benzene dizone chloride reacts with A and water to form benzene.
  • Benzene is then used to create gun amine following Diiso rules for making chloride.
  • Benzene is carcinogenic, causing cancer with prolonged exposure.
  • The journey from benzene to aniline involves nitration, reduction to aniline, and then diazotization.
  • Name reactions like Groves process, Lucas test, Finkle Stein, and Swarts reaction are crucial in organic chemistry.
  • Ulman reaction involves copper in the presence of halide salts to produce aryl halides.
  • Physical properties of alkyl halides and aryl halides make them insoluble in water but soluble in organic solvents due to polar interactions and branching.

03:30:36

Molecular Mass and Boiling Points in Isomers

  • Boiling points are directly proportional to molecular mass and inversely proportional to branching.
  • Molecular mass determines the order of boiling points for alkyne groups.
  • Alkyl groups with higher molecular mass have higher boiling points.
  • As molecular mass increases, the boiling point increases.
  • Isomers with the same molecular formula have the same molecular mass.
  • Branching decreases boiling points in isomers.
  • The order of melting points for isomeric dichlorobenzene is meta, para, and ortho.
  • Symmetry in solid form affects melting points.
  • Density increases with higher molecular mass.
  • Nucleophilic substitution reactions involve the replacement of halogens with nucleophiles.

04:09:06

Understanding Organic Chemistry Reactions and Isomerism

  • Becoming RSH together involves understanding the concept of ether in organic compounds.
  • Nitrogen in ammonia reacts with loan pair on nitrogen to form R-NH2.
  • Further reactions with ammonia can lead to the formation of NH4PX.
  • The primary, secondary, and tertiary Amines are formed based on the presence of nitrogen in compounds.
  • Finklestein reaction involves the reaction of alkyl halide with sodium iodide.
  • The reaction with Gilman reagent (Copper Lithium) results in the formation of alkane.
  • Optical isomerism is crucial in understanding optically active compounds.
  • Optically active compounds rotate plane polarized light either clockwise (dextro) or counterclockwise (levo).
  • To determine optical activity, compounds must satisfy two conditions: non-superimposable mirror images and absence of symmetry elements.
  • Two-chlorobutane is an example of an optically active compound due to its chiral carbon structure.

04:31:11

Chiral Carbon and Optical Activity in Compounds

  • Chiral carbon in a compound makes it optically active
  • Presence of chiral carbon and asymmetric carbon in a compound
  • Compound is optically active if it has more than one chiral carbon
  • Stereoisomerism involves geometric and optical isomers
  • Chiral carbon must be sp3 hybridized with four different valencies
  • Chiral carbon with all four groups different is optically active
  • Mercs are non-superimposable mirror images with same properties
  • Diastereomeric compounds are mirror images with different properties
  • Racemic mixture is a 1:1 equimolar mix of dextro and levo forms
  • Nucleophilic substitution reactions classified as SN1 and SN2, favored in polar protic solvents

04:53:24

Nucleo file and S 2 mechanisms compared.

  • Nucleo file attacks from behind in the Nucleo file mechanism.
  • Inversion occurs when the Nucleo file attacks from behind, leading to Volden inversion.
  • Retention and inversion products are formed in the Nucleo file mechanism.
  • The rate of the reaction in the Nucleo file mechanism depends on the concentration of reactants.
  • The reactivity order of alkyl halides in the Nucleo file mechanism is 3 degrees, then 2 degrees, and finally no degrees.
  • In the Nucleo file mechanism, steric hindrance affects the reactivity order, with smaller groups being more reactive.
  • The S and 2 mechanism occurs in a single step, with the nucleophile attacking from the back.
  • In the S and 2 mechanism, inversion occurs, known as Volden inversion.
  • The rate of reaction in the S and 2 mechanism depends on the concentration of both reactants.
  • The reactivity order of alkyl halides in the S and 2 mechanism is methyl, then primary, then secondary, and finally tertiary.

05:14:18

Steric hindrance impacts reaction speed and products.

  • The carbon with less steric hindrance will lead to a faster reaction due to lower steric crowding.
  • In primary alkynes, the one with less steric hindrance will react faster, with tertiary being the fastest followed by secondary and then primary.
  • Elimination reactions involve the removal of hydrogen and halogen from the alpha and beta carbons, resulting in the formation of alkenes.
  • Beta elimination occurs when hydrogen and halogen are removed from the beta carbon, leading to the formation of alkene products.
  • The major product in elimination reactions is determined by the Set Jaffe rule, where the more substituted alkene is favored as the major product.
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