The resonance structure for the anion of acetonitrile, which is more acidic than ethane, is to be written and step-by-step mechanism for the condensation of benzaldehyde with acetonitrile is to be given. Concept introduction: 舧 Electrophiles are electron-deficient species, which has positive or partially positive charge. Lewis acids are electrophiles, which accept electron pair. 舧 Nucleophiles are electron-rich species, which has negative or partially negative charge. Lewis bases are nucleophiles, which donate electron pair. 舧 Free radical is an atom, molecule, or ion that has an unpaired electron, which makes it highly chemically reactive. 舧 Substitution reaction: A reaction in which one of the hydrogen atoms of a hydrocarbon or a functional group is substituted by any other functional group is called substitution reaction. 舧 Elimination reaction: A reaction in which two substituent groups are detached and a double bond is formed is called elimination reaction. 舧 Addition reaction: It is the reaction in which unsaturated bonds are converted to saturated molecules by the addition of molecules. 舧 In nitrile, alpha hydrogen is weakly acidic, so the nitrile undergoes aldol-type condensation. 舧 A carbon-carbon bond formation occurs by aldol addition and aldol condensation reaction. 舧 An aldol reaction takes place by acid catalysis, and direct dehydration of β − hydroxy aldol intermediate forms α , β − unsaturated product. 舧 A chemical reaction that is catalyzed by an acid is called acid-catalyzed reaction. 舧 A chemical reaction that is catalyzed by a base is called base-catalyzed reaction. 舧 Aldol reaction is preferred in basic condition over acidic condition as after the aldol condensation, acid catalysis promotes the reaction further. 舧 An aldol reaction takes place in a protic solvent with a base. 舧 Dehydration of aldol addition product leads to the formation of conjugated α , β − unsaturated carbonyl compound and the overall reaction is aldol condensation. The rules for drawing resonance structures are as follows: 舧 Only nonbonding electron pairs and pi electrons can participate in conjugation in the formation of various resonating structures. 舧 The single bonds present in the molecule do not break or form in the resonance structures. 舧 The placement of atoms present in the molecule remains fixed. 舧 The octet of all atoms is completely filled. 舧 More the number of resonance structures indicate higher stability of a compound.

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Chapter 19, Problem 14PP

Interpretation Introduction

Interpretation:

The resonance structure for the anion of acetonitrile, which is more acidic than ethane, is to be written and step-by-step mechanism for the condensation of benzaldehyde with acetonitrile is to be given.

Concept introduction:

舧 Electrophiles are electron-deficient species, which has positive or partially positive charge. Lewis acids are electrophiles, which accept electron pair.

舧 Nucleophiles are electron-rich species, which has negative or partially negative charge. Lewis bases are nucleophiles, which donate electron pair.

舧 Free radical is an atom, molecule, or ion that has an unpaired electron, which makes it highly chemically reactive.

舧 Substitution reaction: A reaction in which one of the hydrogen atoms of a hydrocarbon or a functional group is substituted by any other functional group is called substitution reaction.

舧 Elimination reaction: A reaction in which two substituent groups are detached and a double bond is formed is called elimination reaction.

舧 Addition reaction: It is the reaction in which unsaturated bonds are converted to saturated molecules by the addition of molecules.

舧 In nitrile, alpha hydrogen is weakly acidic, so the nitrile undergoes aldol-type condensation.

舧 A carbon-carbon bond formation occurs by aldol addition and aldol condensation reaction.

舧 An aldol reaction takes place by acid catalysis, and direct dehydration of β− hydroxy aldol intermediate forms α,β− unsaturated product.

舧 A chemical reaction that is catalyzed by an acid is called acid-catalyzed reaction.

舧 A chemical reaction that is catalyzed by a base is called base-catalyzed reaction.

舧 Aldol reaction is preferred in basic condition over acidic condition as after the aldol condensation, acid catalysis promotes the reaction further.

舧 An aldol reaction takes place in a protic solvent with a base.

舧 Dehydration of aldol addition product leads to the formation of conjugated α,β− unsaturated carbonyl compound and the overall reaction is aldol condensation.

The rules for drawing resonance structures are as follows:

舧 Only nonbonding electron pairs and pi electrons can participate in conjugation in the formation of various resonating structures.

舧 The single bonds present in the molecule do not break or form in the resonance structures.

舧 The placement of atoms present in the molecule remains fixed.

舧 The octet of all atoms is completely filled.

舧 More the number of resonance structures indicate higher stability of a compound.

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