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Chemistry · Class 11 Science

Ch 11Organic Chemistry: Some Basic Principles — Class 11 Chemistry, concept-first.

For much of the eighteenth century, chemists believed that compounds obtained from living organisms were governed by a mysterious 'vital force' and could never be prepared from non-living (inorganic) starting materials -- a doctrine called vitalism.

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Classification of Organic Compounds

With millions of known organic compounds, classifying them by two independent lenses -- overall carbon-skeleton structure, and functional group -- is what makes the subject navigable at all.

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11.1

General Introduction to Organic Chemistry

For much of the eighteenth century, chemists believed that compounds obtained from living organisms were governed by a mysterious 'vital force' and could never be prepared from non-living (inorganic)…

11.2

Classification of Organic Compounds

Organic compounds are first classified by the shape of their carbon skeleton. Open-chain (acyclic or aliphatic) compounds have carbon atoms joined in a continuous chain, straight or branched, with no…

11.3

IUPAC Nomenclature — Basic Rules for Hydrocarbons

The IUPAC (International Union of Pure and Applied Chemistry) system gives every organic compound exactly one systematic name, built up in a fixed sequence of steps.

11.4

IUPAC Nomenclature of Compounds Containing a Functional Group

Many organic molecules carry, in addition to a plain carbon skeleton, one or more functional groups -- specific atoms or groups of atoms, such as , , or , that are chiefly responsible for the molecule…

11.5

Electronic Displacement in a Covalent Bond: Inductive Effect

When two atoms of different electronegativity are joined by a covalent bond, the shared electron pair is not shared equally -- it lies closer to the more electronegative atom, which develops a small n…

11.6

Resonance and the Resonance Effect

For some molecules and ions, no single Lewis (electron-dot) structure can correctly represent the real distribution of electrons and bond lengths observed experimentally.

11.7

Hyperconjugation

Hyperconjugation, sometimes called 'no-bond resonance', is a permanent stabilising interaction in which electron density from a filled carbon-hydrogen (or occasionally carbon-carbon) sigma bond deloca…

11.8

Fission of a Covalent Bond: Homolytic and Heterolytic Fission; Free Radicals

A covalent bond can break, or 'fission', in two fundamentally different ways, and which pathway a given bond follows determines what kind of reactive species is produced.

11.9

Carbocations and Carbanions: Structure and Relative Stability

Carbocations are carbon species bearing a positive charge, formed when heterolytic fission leaves a carbon atom with only three bonds and six electrons around it (an 'electron sextet') rather than the…

11.10

Electrophiles and Nucleophiles

Every reagent that attacks an organic substrate during a reaction can be sorted into one of two broad categories, based on whether it is short of electrons or rich in them.

11.11

Types of Organic Reactions: Addition, Elimination and Substitution

With the electronic groundwork of Sections 11.5 to 11.10 in place, most reactions met at this stage of organic chemistry can be sorted into one of three broad patterns.

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  1. Example 1Classify the following as open-chain (acyclic), alicyclic or aromatic compounds: (a) hexane, CH3-CH2-CH2-CH2-CH2-CH3 (b) cyclohexane (c) ben…Free
  2. Example 2What is a homologous series? Using the alkane series (general formula CnH2n+2) as your example, write the molecular formulas of the first fo…Free
  3. Example 3Write the IUPAC name of CH3-CH2-CH(CH3)-CH2-CH3.Free
  4. Example 4Write the IUPAC name of CH2=CH-CH(CH3)-CH3.Preview
  5. Example 5Write the IUPAC name of CH3-CH(OH)-CH2-CH2-CH3.Preview
  6. Example 6Write the IUPAC name of CH3-CO-CH2-CH2-CHO. Explain why the aldehyde group, and not the ketone group, is chosen as the principal characteris…Preview
  7. Example 7Draw the structural formula of the compound named 3-methylpentan-2-ol.Preview
  8. Example 8Chloroacetic acid (CH2ClCOOH) is a stronger acid than acetic acid (CH3COOH). Explain this using the inductive effect.Preview
  9. Example 9Draw the two resonance (canonical) structures of the acetate ion, CH3COO(-), and state what they predict about the two carbon-oxygen bond le…Preview
  10. Example 10Explain how hyperconjugation operates in propene, CH3-CH=CH2, and identify which C-H bonds are involved.Preview
  11. Example 11Distinguish between homolytic and heterolytic fission of a covalent bond, illustrating each with one example: (a) Cl2 splitting under sunlig…Preview
  12. Example 12Arrange the methyl cation, and the primary, secondary and tertiary carbocations in increasing order of stability, and explain the order.Preview
  13. Example 13In the reaction CH3Br + OH(-) -> CH3OH + Br(-), identify the electrophile and the nucleophile and explain your choice.Preview
  14. Example 14Classify the following reaction as addition, elimination or substitution, and name the type of reagent that attacks the substrate: CH2=CH2 +…Preview
  15. Example 15Classify the following reaction as addition, elimination or substitution: CH3-CH2-Br + alc. KOH --heat--> CH2=CH2 + KBr + H2O.Preview
+Show 15 questions15 questions
  1. Q16Classify each of the following into open-chain, alicyclic, aromatic or heterocyclic compounds: (a) CH3-CH2-CH2-CH3 (b) cyclopropane (c) naph…Free
  2. Q17Alkynes follow the general formula CnH2n-2. A certain hydrocarbon has the molecular formula C5H8 and belongs to this homologous series. Name…Free
  3. Q18Write the IUPAC name of (CH3)3C-CH2-CH3.Free
  4. Q19Write the IUPAC name of CH#C-CH2-CH3 (a triple bond between the first two carbons).Preview
  5. Q20Write the IUPAC name of CH2=CH-CH2-OH.Preview
  6. Q21Write the IUPAC name of CH3-NH2.Preview
  7. Q22Write the IUPAC name of CH3-CH(CH3)-CH2-CH(C2H5)-CH2-CH3, and explain (i) why the substituents are numbered 2 and 4 rather than 3 and 5, and…Preview
  8. Q23Arrange acetic acid (CH3COOH), chloroacetic acid (ClCH2COOH), dichloroacetic acid (Cl2CHCOOH) and trichloroacetic acid (Cl3CCOOH) in increas…Preview
  9. Q24The allyl cation, CH2=CH-CH2(+), is more stable than a simple primary carbocation of comparable size. Draw its resonance structures and expl…Preview
  10. Q25Explain, in terms of hyperconjugation, why propene (CH3-CH=CH2) is more stable than ethene (CH2=CH2).Preview
  11. Q26In the free-radical chlorination of methane, the first (initiation) step is Cl2 --sunlight--> 2Cl(dot). Name the type of bond fission occurr…Preview
  12. Q27Arrange the methyl carbanion and the primary, secondary and tertiary carbanions in decreasing order of stability, and explain why this order…Preview
  13. Q28Classify each of the following as an electrophile or a nucleophile, giving a reason in each case: BF3, NH3, Br(+), CN(-).Preview
  14. Q29Classify the following reaction as addition, elimination or substitution: CH3-CH2-OH + HBr -> CH3-CH2-Br + H2O.Preview
  15. Q30Classify the following reaction as addition, elimination or substitution, and name the nucleophile involved: CH3-CH2-Br + NaCN -> CH3-CH2-CN…Preview