Ch. 3 - Acids and BasesWorksheetSee all chapters
All Chapters
Ch. 1 - A Review of General Chemistry
Ch. 2 - Molecular Representations
Ch. 3 - Acids and Bases
Ch. 4 - Alkanes and Cycloalkanes
Ch. 5 - Chirality
Ch. 6 - Thermodynamics and Kinetics
Ch. 7 - Substitution Reactions
Ch. 8 - Elimination Reactions
Ch. 9 - Alkenes and Alkynes
Ch. 10 - Addition Reactions
Ch. 11 - Radical Reactions
Ch. 12 - Alcohols, Ethers, Epoxides and Thiols
Ch. 13 - Alcohols and Carbonyl Compounds
Ch. 14 - Synthetic Techniques
Ch. 15 - Analytical Techniques: IR, NMR, Mass Spect
Ch. 16 - Conjugated Systems
Ch. 17 - Aromaticity
Ch. 18 - Reactions of Aromatics: EAS and Beyond
Ch. 19 - Aldehydes and Ketones: Nucleophilic Addition
Ch. 20 - Carboxylic Acid Derivatives: NAS
Ch. 21 - Enolate Chemistry: Reactions at the Alpha-Carbon
Ch. 22 - Condensation Chemistry
Ch. 23 - Amines
Ch. 24 - Carbohydrates
Ch. 25 - Phenols
Ch. 26 - Amino Acids, Peptides, and Proteins
Reactivity

Did you know that not all molecules are reactive? Only certain types of molecules will want to react in a mechanism. Let’s dig a little deeper into this...

Stability and reactivity generally have an inverse relationship. If a molecule is unstable in some way, it will want to react! Here are the 4 signs we can look for that determine reactivity:

Concept #1: How to tell if a molecule will be reactive or not.  

These reactive trends ARE in order of strength (i.e. a formal charge will typically be more reactive than a dipole).  

Using those indicators, let's see if the following molecules are reactive:

Example #1: Are any of the following 4 molecules reactive?  

Example #2: Are any of the following 4 molecules reactive?  

Again, we are literally just matching these molecules to the 4 patterns discussed above. 

Nucleophiles vs. Electrophiles

Concept #2: How to tell if charged molecules will react as nucleophiles or electrophiles.

Now that we know how to determine if molecules are reactive, we still don’t know HOW they will react! There are two major subtypes of reactivity that we’ll often use in Orgo 1 and 2: 

Note that a molecule doesn’t require a negative charge to be a nucleophile, but it needs to have similar properties (i.e. a source of electrons).

That said, try to identify if the following three molecules are nucleophilic or electrophilic. 

Example #3: Are the following 3 reactive molecules nucleophiles or electrophiles?    

Concept #3: How to tell if uncharged molecules will react as nucleophiles or electrophiles.

So that wasn’t so hard, but those were the easy cases. What if you have nucleophilic AND electrophilic regions on the same molecule? Is it possible to determine how it will react? Yes it is!

Rule: The side of the dipole with the highest bonding preference (the atom that wants to make the most bonds) will determine how the molecule reacts. 

Example #4: Are the following 3 reactive molecules nucleophiles or electrophiles?    

Bond Making

Now we understand which molecules will want to react, and we are getting better at determining If they are nucleophiles or electrophiles, but how to they actually attack other molecules?

Reactive molecules share electrons to become more stable. Arrows are used to show which direction they are going.

  • Arrows always move from regions of high electron density to low electron density
  • By that logic, nucleophiles must always attack electrophiles.
  • Each attacking arrow represents two electrons being shared.
    • After the reaction is complete, replace that arrow with a new σ -bond

Summary: Molecules with lots of electrons will attack (draw an arrow to) molecules with a positive charge. Let’s get drawing!

Concept #4: Learning the rules of electron movement 

Using those rules, let's draw the mechanisms for the following reactions

Example #5: Draw the first arrow of the following mechanism. 

Example #6: Draw the first arrow of the following mechanism 

Example #7: Draw the first arrow of the following mechanism 

Bond Breaking

So now we know how to make bonds. Do we ever have to break bonds? How do we know if we do or we don’t?

Concept #5: Why we need to break bonds sometimes.

Bond breaking is sometimes required in mechanisms, but only when it is necessary to preserve octets.

Concept #6: The two ways to break bonds.

Out of these two different ways, we will stick to heterolytic cleavage for the foreseeable future (we won’t discuss radicals for a few more chapters). 

Identify if the following reactions require bonds to be broken. Draw the products.

Example #8: Identify if the following reaction requires a bond to be broken. Draw the products.

Example #9: Identify if the following reaction requires a bond to be broken. Draw the products.

Example #10: Identify if the following reaction requires a bond to be broken. Draw the products. 

Additional Problems
Draw curved arrows on the reactant side of the reaction arrow to show how electron pairs move in the formation of the indicated products.
Provide the product(s) for the following mechanistic steps based on the curved arrows show. 
Which one represents a bond heterolysis? 
Draw the curved arrow mechanism and products for the following reaction. 
Supply curved arrows for the following reactions.
Predict the product(s) of the following reactions:
For each of the following one step transformations show the movement of electrons by using the standard curved arrow notation. Show all formal charges for each structure on the left and right of the reaction arrows.
For the following mechanism, identify the sequence of arrow-pushing patterns:
Compound 1 undergoes a thermal elimination of nitrogen at C to form nitrile  4 (Org. Lett. 1999, 1, 537–539). One proposed subsequently refuted) mechanism for this transformation involves intermediates 2 and 3:  (a) Draw curved arrows that show the conversion of  2 to 3.
The following is a generic depiction of a reaction using the curved arrow formalism. Which of these statements is not correct for this reaction? a. Electrons move from C to B. b. In the products, A would have a positive charge. c. In the products, a bond forms between C and B. d. Electrons move from B to A.  
For the following mechanism, identify the sequence of arrow-pushing patterns:  
For the following mechanism, identify the sequence of arrow-pushing patterns:
For the following mechanism, identify the sequence of arrow-pushing patterns:
For the following mechanism, identify the sequence of arrow-pushing patterns:
For the following mechanism, identify the sequence of arrow-pushing patterns:
For the following mechanism, identify the sequence of arrow-pushing patterns:  
For the following mechanism, identify the sequence of arrow-pushing patterns:   
Draw curved arrows for each step of the following mechanism:  
Draw the curved arrow that shows the  electron flow and indicate the pattern (proton transfer, nucleophilic attack, carbocation rearragement, or loss of leaving group), for each of the following reaction steps. 
Write an equation for the proton transfer reaction that occurs when each of the following acids reacts with water. In each case, draw curved arrows that show the mechanism of the proton transfer: (a) HBr
The following sequence was utilized in a biosynthetically inspired synthesis of preussomerin, an antifungal agent isolated from a coprophilous (dung-loving) fungus (Org. Lett. 1999, 1, 3–5):  (a) Draw curved arrows for each step of the mechanism.
Draw curved arrows for each step of the following mechanism:
Write an equation for the proton transfer reaction that occurs when each of the following acids reacts with water. In each case, draw curved arrows that show the mechanism of the proton transfer:
Draw curved arrows for each step of the following mechanism:
Write an equation for the proton transfer reaction that  occurs when each of the following bases reacts with water. In each case, draw curved arrows that show the mechanism of the proton transfer:
Write an equation for the proton transfer reaction that  occurs when each of the following bases reacts with water. In each case, draw curved arrows that show the mechanism of the proton transfer:
Write an equation for the proton transfer reaction that  occurs when each of the following bases reacts with water. In each case, draw curved arrows that show the mechanism of the proton transfer:
The following reaction has three mechanic steps. Draw all curved arrows necessary to complete the mechanism.
Write an equation for the proton transfer reaction that  occurs when each of the following bases reacts with water. In each case, draw curved arrows that show the mechanism of the proton transfer:
Draw curved arrows to represent the flow of electrons in each step, and indicate the missing fragments in the box
Rewrite each of the following reactions using curved arrows and show all nonbonding electron pairs: (a) CH3OH + Hl → CH3OH2+ + l-
 Given the reaction below, please predict the curved arrow mechanism.    
Rewrite each of the following reactions using curved arrows and show all nonbonding electron pairs: (b) CH3NH2 + HCl → CH3NH3+ + Cl-
Rewrite each of the following reactions using curved arrows and show all nonbonding electron pairs:
Follow the curved arrows and write the products.
Follow the curved arrows and write the products.
Follow the curved arrows and write the products.
For each step of the following mechanism: a) Draw curved arrows b) Identify arrow-pushing patterns
Supply the curved arrows necessary for the following reactions:
Supply the curved arrows necessary for the following reactions:
Supply the curved arrows necessary for the following reactions:
Supply the curved arrows necessary for the following reactions:
Supply the curved arrows necessary for the following reactions:
Follow the flow of electron indicated by the curved arrows predict the products of the reaction.
What pattern of curved arrow pushing is the second step of this reaction?  a) Proton transfer b) Rearrangement c) Loss of leaving group d) Nucleophilic attack
For the following transformation, use curved arrow notation (electron-pushing) to show the movement of electrons. Show all formal charges.
For each of the following reactions identify the arrow-pushing pattern that is being utilized:
In the presence of a Lewis acid, compound  1 rearranges, via intermediate 2, to afford compound 3. (a) Draw curved arrows showing how 1 is transformed into 2. Note that the Lewis acid has been left out for simplicity. 
Compound 1 undergoes a thermal elimination of nitrogen at C to form nitrile  4 (Org. Lett. 1999, 1, 537–539). One proposed subsequently refuted) mechanism for this transformation involves intermediates 2 and 3: (b) To determine whether or not the proposed mechanism operates, one of the nitrogen atoms was isotopically labeled as 15N, and its location in the product was determined. The absence of 4b in the product mixture demonstrates that the proposed mechanism is not operating. Using resonance structures, explain why the proposed mechanism predicts that 4b should be formed. 
What are the products of the following reaction based on the electron flow represented by the curved arrows?
Write an equation for the proton transfer reaction that occurs when each of the following acids reacts with water. In each case, draw curved arrows that show the mechanism of the proton transfer:
Indolizomycin is a potent antibiotic agent produced by a microorganism called SK2-52. Of particular interest is the fact that SK2-52 is a mutant microorganism that was created in a laboratory from two different strains, Streptomyces teryimanensis and Streptomyces grisline, neither of which is antibiotic producing. This raises the possibility of using mutant microorganisms as factories for producing novel structures with a variety of medicinal properties. During S. J. Danishefsky’s synthesis of racemic indolizomycin, compound 1 was treated with triphenylphosphine (PPh3) to afford compound 2 (J. Am. Chem. Soc. 1990, 112, 2003–2005). The reaction between 2 and 3 then gave compound 4. These processes are believed to proceed via the following intermediates. Complete the mechanism by drawing all curved arrows and identify the arrow-pushing pattern employed in each step. 
Compound 1 has been prepared and studied to investigate a novel type of intramolecular elimination mechanism (J. Org. Chem. 2007, 72, 793–798). The proposed mechanistic pathway for this transformation is presented below. Complete the mechanism by drawing curved arrows consistent with the change in bonding in each step. 
As noted in Table 3.1, the pKa of acetone, CH3COCH3, is 19.2. (c) Write an equation for a reaction that could be used to synthesize CH3COCH2D.
Deuterium (D) is an isotope of hydrogen, in which the nucleus has one proton and one neutron. This nucleus, called a deuteron, behaves very much like a proton, although there are observed differences in the rates of reactions involving either protons or deuterons (an effect called the kinetic isotope effect). Deuterium can be introduced into a compound via the process below:(a) The C—Mg bond in compound  3 can be drawn as ionic. Redraw 3 as an ionic species, with BrMg + as a counterion, and then draw the mechanism for the conversion of  3 to 4.
Draw the products of the reaction shown. Electron flow is indicated with curved arrows. 
Draw the products of the reaction shown. Electron flow is indicated with curved arrows.
Draw the products of the reaction shown. Electron flow is indicated with curved arrows.  
Noting the curved arrows, draw the produce(s), organic and inorganic, of the following reaction. 
The curved arrows below are showing electron movement to convert the molecule below into which resonance structure? 
Noting the curved arrows, draw all the product(s), organic and inorganic, of the following reaction.
Which of the following reactions show an incorrect arrow pushing?
Draw the products of the reaction shown. Electron flow is indicated with curved arrows.
Draw the products of the reaction shown. Electron flow is indicated with curved arrows.