Reaction types, nucleophiles and electrophiles, and Curly Arrows Flashcards
What is an acid/base reaction?
What is a substitution reaction?
- It’s a reaction where one functional group in a chemical compound is replaced by another functional group.
What is an addition reaction?
- A reaction in which one molecule combines with another to form a larger molecule with no other products.
- From double to single bonds
Name the 5 main types of reactions that a molecule can go through.
- Acid-base reaction
- Substitution
- Addition
- Elimination
- Oxidation and reduction
What is an elemination reaction?
- Two substituents are removed from a molecule in either a one or two-step mechanism
- Opposite to addition
What is an oxidation reaction?
- Oxidation is loss of electrons
- Decrease in CH bonds and increase in OH bonds
- Oxygen content percentage goes up as we loss hydrogen.
- It’s the loss of hydrogen as hydrogen takes two electrons with it, making the compound lose electrons.
What is a reduction reaction?
- Gain of electrons
- Oxygen content of the molecule as a function of mass has gone down
- Reduction is the gain of H
Which compounds have the largest acidity?
Compounds that have an OH group attached
What does a curly arrow represent?
It represents electron pair movement
Describe the movement of a curly arrow
- A curly arrow starts at the electron pair that moves and ends at the atom to which the electron pair has moved
What does a curly arrow pointing away from a bond mean?
- An arrow from a bond indicates breaking of that bond
What does an arrow between two species mean?
- An arrow between two species indicates a bond is formed between the species
How do curly arrows help explain acidity?
- Difference in acidity results from resonance stabilisation of the anion
What is resonance?
- The two extremes of a structure
- The real structure is in the middle
What is an electrophile?
- An electrophile seeks lone pairs
- It’s electron deficient (are positively charged)
- The curly arrows end at the electrophile
- eg. H+, HCl, NO2+
What is a nucleophile?
- Nucleophiles (donate electron pairs) eg OH¯, Br¯, :NH3
- Negatively charged
- electron rich
- The curly arrow starts at the nucleophile
Are electrophiles or nucleophiles attracted to the pi bond?
Electrophiles are attracted to the pi bond
Name the 4 alkene reactions
- Halogenation
- Hydration
- Hydrohalogenation
- Hydrogenation
What is Hydrogenation?
- The addition of hydrogen in a reaction
- Catalyst is required to break the H-H bond
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What is halogenation?
- The addition of a halogen in a reaction
What is hydrohalogenation?
- The addition of hydrogen and halogen (hydrogen halide)
What is hydration?
- Addition of water to a reaction
What is a triple bond composed of?
- A triple bond is composed of a sigma bond and two pi bonds
- electrophilic reacts occur to both pi bonds.
