Organic Chemistry Halogenation and Reactivity Quiz

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Questions and Answers

What is the product formed when methane (CH4) reacts with chlorine (Cl2) in the presence of sunlight?

Methylene chloride (CH2Cl2)

Chloroform (CHCl3)

Carbon tetrachloride (CCl4)

Methyl chloride (CH3Cl) (correct)

Which of the following statements is TRUE about the reactivity of halogens towards alkane halogenation?

The reactivity decreases down the group. (correct)

The reactivity increases down the group.

The reactivity is independent of the position of the halogen in the periodic table.

The reactivity remains constant down the group.

What is the main product formed when propane (CH3CH2CH3) undergoes nitration?

2-nitropropane (CH3CH(NO2)CH3)

A mixture of 1-nitropropane and 2-nitropropane. (correct)

1-nitropropane (CH3CH2CH2NO2)

Nitroethane (CH3CH2NO2)

Which of the following alkanes undergoes sulfonation when treated with fuming H2SO4?

Hexane (C6H14) (C) Signup and view all the answers

What are the products formed when ethane (C2H6) undergoes complete combustion in the presence of oxygen?

Carbon dioxide (CO2) and water (H2O) (D) Signup and view all the answers

Which of the following statements is TRUE about the reactivity of alkanes towards halogenation?

Tertiary carbons are the most reactive. (B) Signup and view all the answers

What is the main reason for the decreasing reactivity of halogens down a group in the periodic table?

Decreasing electronegativity of the halogen atoms. (C) Signup and view all the answers

Which of the following reactions is NOT a characteristic reaction of alkanes?

Addition (C) Signup and view all the answers

What is the main product formed from the dehydrohalogenation of vicinal dihalides in the presence of zinc dust and an alcoholic solution?

Alkenes (D) Signup and view all the answers

Which method produces alkenes at the anode through electrolysis of sodium or potassium salts of dicarboxylic acid?

Kolbe's electrolysis (C) Signup and view all the answers

What is the main difference in melting point between cis and trans isomers of alkenes?

Trans isomers generally have a higher melting point due to their greater symmetry and ability to form more stable crystal lattices. (D) Signup and view all the answers

Which reaction condition favors the formation of trans alkenes?

Reaction with Li in liquid ammonia (D) Signup and view all the answers

What is the main characteristic that makes alkenes reactive?

The presence of a double bond (B) Signup and view all the answers

What is the product formed when tributyl borane is oxidized with hydrogen peroxide and hydroxide ions?

Alcohol (C) Signup and view all the answers

What is the most reactive hydrogen halide in alkene addition reactions?

HI (D) Signup and view all the answers

Which of the following reactions occurs with a trans addition?

Oxidation by peracids (RCO3H) (E) Signup and view all the answers

Which rule predicts the regioselectivity of the addition of hydrogen halides to unsymmetrical alkenes?

Markovnikov's Rule (B) Signup and view all the answers

Which condition leads to the anti-Markovnikov addition of HBr to unsymmetrical alkenes?

Presence of light or peroxides (D) Signup and view all the answers

Which of the following is a test used to detect double bonds in alkenes?

Oxidation by cold alkaline KMnO4 (C) Signup and view all the answers

Which of the following reactions gives an alcohol as a product?

Addition of water (B), Hydroboration followed by oxidation (D) Signup and view all the answers

What is the product formed when a trans alkene is oxidized by a peracid?

Meso compound (B) Signup and view all the answers

What is the main difference between the addition of water and the hydroboration reaction?

Hydroboration follows the Anti-Markovnikov rule, while the addition of water follows Markovnikov's rule. (A) Signup and view all the answers

What is the name of the process of adding an alkane to an alkene?

Alkylation (B) Signup and view all the answers

What is the product formed when a cis alkene is oxidized by cold alkaline KMnO4?

Meso compound (C) Signup and view all the answers

What is the product formed when propene reacts with HOCl?

CH3CH2CH(OH)Cl (B) Signup and view all the answers

Which of the following is NOT a characteristic of alkynes?

They are typically more stable than alkanes. (B) Signup and view all the answers

What is the product formed when an alkene undergoes allylic bromination using NBS?

An alkene with a bromine atom at the allylic carbon. (C) Signup and view all the answers

What is the best method to achieve chlorination of alkenes?

Reaction with chlorine gas in liquid phase. (A) Signup and view all the answers

Based on the given information, which of the following explains why alkene with the lowest heat of hydrogenation is the most stable?

Higher heat of hydrogenation usually means that the alkene is less stable. (C) Signup and view all the answers

What is the main product (A) formed when cis-but-2-ene reacts with alkaline KMnO4?

Meso-1, 2-butan-di-ol (A) Signup and view all the answers

Consider the reaction of an alkene with ozone followed by a reductive workup. What are the expected products X and Y for the alkene CH3-CH=CH-CH3?

CH3-COOH (2 moles) (C) Signup and view all the answers

What is the most likely intermediate formed in the reaction of propene with HOCl?

CH3-CHCl-CH2+ (B) Signup and view all the answers

What is the general formula for alkenes?

C_nH_2n (A) Signup and view all the answers

Which of the following is NOT a structural isomer of butene?

CH_3 - CH_2 - CH_2 - CH_3 (A) Signup and view all the answers

What is the main product formed when 2-bromobutane undergoes dehydrohalogenation in the presence of alcoholic KOH?

But-2-ene (C) Signup and view all the answers

Which of the following is NOT an example of an elimination reaction?

Wurtz reaction (D) Signup and view all the answers

Why is cis-but-2-ene considered a stereoisomer of trans-but-2-ene?

They have the same molecular formula but different spatial arrangements. (A) Signup and view all the answers

What is the order of reactivity of alkyl halides in dehydrohalogenation?

Tertiary > secondary > primary (D) Signup and view all the answers

Which of the following statements regarding alkene preparation is TRUE?

Dehydrohalogenation of an alkyl halide with alcoholic KOH can produce multiple alkene isomers. (D) Signup and view all the answers

In the reaction of a free radical with an alkane, the major product is formed by attack at the

tertiary carbon. (A) Signup and view all the answers

What is the product formed when acetylene is oxidized with acidic KMnO4?

Oxalic acid (D) Signup and view all the answers

What is the name of the compound that forms when acetylene reacts with sodium in liquid ammonia?

Sodium acetylide (C) Signup and view all the answers

What type of reaction is the reaction of acetylene with ammonical cuprous chloride?

Substitution (D) Signup and view all the answers

Which of the following is NOT a product of the oxymercuration reaction of 1-butyne?

Butane (B) Signup and view all the answers

Which reagent can be used to distinguish between acetylene and ethane?

Ammonical cuprous chloride (A) Signup and view all the answers

What is the main characteristic that makes the hydrogen atom in alkynes acidic?

The hybridization of the carbon atom in the triple bond (A) Signup and view all the answers

Which of the following statements is true about the oxidation of alkynes with K2Cr2O7 in acidic medium?

It always forms carboxylic acids. (D) Signup and view all the answers

Which of the following statements is true about the reaction of acetylene with sodium amide (NaNH2)?

It forms a disodium acetylide. (B) Signup and view all the answers

Study Notes

Alkanes

Alkanes are the simplest saturated hydrocarbons, also called paraffins.
Their general formula is CnH2n+2.
Carbon atoms in alkanes are sp³ hybridized.
They have a tetrahedral shape.
The bond length between C-H is 1.124 Å.
The bond length between C-C is 1.544 Å.
Methane (CH₄) is the simplest alkane.

Conformation

Alkanes have various conformers due to free rotation around C-C single bonds.
Different spatial arrangements of atoms lead to conformers or rotamers.
Ethane has two types of conformations: staggered and eclipsed.
Staggered conformation is more stable than eclipsed due to less steric hindrance.

Methods of Preparation

Catalytic hydrogenation of unsaturated hydrocarbons: Adding hydrogen to unsaturated hydrocarbons in the presence of a catalyst (e.g., nickel, 200-300°C, or Raney Ni) for reduction.
Reduction of alkyl halides: Using a reducing agent in the presence of a catalyst such as Zn + CH3COOH, Zn + HCl, Zn + NaOH, Zn + Cu along with an alcohol (C₂H₅OH) or aluminum amalgam, or LiAlH₄, to reduce alkyl halides.
Reduction of alcohols, aldehydes, and ketones: Reducing these compounds with hot hydroiodic acid (HI) and red phosphorus (P) at 150°C in a sealed tube to produce alkanes.

Physical Properties

Alkanes are colorless and odorless gases, liquids, or solids depending on molecular mass.
Density increases with increasing molecular mass.
They are insoluble in polar solvents (like water) but soluble in nonpolar solvents (like ether, CCl₄, benzene).
Boiling and melting points increase with increasing molecular mass but this isn't always smooth for alkanes.

Chemical Properties

Alkanes are relatively unreactive due to strong C-C and C-H bonds under normal conditions.
Halogenation (free radical substitution): Alkanes react with halogens (Cl₂, Br₂) in the presence of light or high temperatures to form halogenated alkanes.
Other reactions (at high temperatures): Alkanes can undergo nitration, sulphonation, oxidation, etc

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Description

Test your knowledge on the reactions and properties of alkanes and halogens. This quiz covers topics such as alkane halogenation, nitration of propane, and the effects of sunlight on these reactions. Answer questions related to the reactivity of halogens and the outcomes of various reactions involving alkanes.