Haloalkanes
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In nucleophilic substitution, what type of bond is polar?
C-X bond The electrons in the C-X bond are attracted towards the halogen atom, resulting in a slight negative charge on the halogen and a slight positive charge on the carbon.
What charge does the carbon atom have in a polar C-X bond?
Slight positive charge This occurs because the electrons are attracted towards the halogen atom.
What type of species attacks the electron deficient carbon atom in nucleophilic substitution?
Nucleophile A nucleophile contains a lone pair of electrons that it donates to the carbon atom.
What happens to the carbon-halogen bond during nucleophilic substitution?
It breaks by heterolytic fission This results in the release of a halide ion.
In nucleophilic substitution, what is substituted for a nucleophile?
Halide ion The halide ion is replaced by the nucleophile in the reaction.
Fill in the blank: The reaction type where a halide ion is substituted for a nucleophile is known as ________.
nucleophilic substitution This reaction involves the attack of a nucleophile on an electron deficient carbon atom.
What’s the general formula for haloalkanes?
CnH2n+1X
What is a nucleophile?
A lone pair donor Nucleophiles are species that donate an electron pair to form a covalent bond.
In nucleophilic substitution, what does the lone pair on the nucleophile form with the carbon atom?
A covalent bond This process is illustrated using a curly arrow.
What happens to the two electrons in the C-X bond during nucleophilic substitution?
They move onto the halogen atom, breaking the C-X bond This process is known as heterolytic fission and is shown using a curly arrow.
What is formed when the halogen atom gains electrons from the bond?
A halide ion This occurs as a result of the breaking of the C-X bond.
What is the reagent used in the hydrolysis reaction with hydroxide ions?
NaOH(aq) This reaction forms alcohols when haloalkanes are warmed with aqueous sodium hydroxide.
What are the conditions for the hydrolysis reaction with hydroxide ions?
Warm, aqueous This is necessary for the reaction to occur effectively.
What is the overall reaction when CH3CH2Br reacts with NaOH?
CH3CH2Br + NaOH → CH3CH2OH + NaBr This reaction illustrates the formation of alcohols from haloalkanes.
What is the mechanism of the reaction when haloalkanes react with hydroxide ions?
Nucleophilic substitution This mechanism describes how the nucleophile replaces the halogen in the haloalkane.
What is the experiment used to show the rate of hydrolysis of haloalkanes?
Warm separate samples of 1-chloropropane, 1-bromopropane, and 1-iodopropane in ethanol, add aqueous silver nitrate, and time the precipitate formation Do not use NaOH or KOH for this reaction.
What is the slowest haloalkane in the hydrolysis experiment?
1-chloropropane It produces a white precipitate.
What is the fastest haloalkane in the hydrolysis experiment?
1-iodopropane It produces a yellow precipitate.
What color of precipitate does 1-bromopropane produce?
Cream This indicates its intermediate reaction rate compared to the other haloalkanes.
What happens to the rate of hydrolysis as we go down the group of haloalkanes?
Increases This trend is due to the strength of the C-X bond decreasing down the group.
What is the ionic equation for precipitation in the hydrolysis experiment?
Ag^+ + X^- → AgX Where X represents the halide ion from the haloalkane.
What is the reagent used to form nitriles from haloalkanes?
KCN dissolved in ethanol (ethanolic KCN) This reagent facilitates the nucleophilic substitution reaction to form nitriles.
What type of reaction occurs when haloalkanes are warmed with ethanolic KCN?
Nucleophilic substitution This reaction results in the formation of nitriles.
What is the nucleophile in the reaction involving KCN?
:CN (cyanide ion) The cyanide ion acts as a nucleophile in the formation of nitriles.