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Common Reagents in Organic Synthesis Cheat Sheet
A printable reference covering oxidation, reduction, substitution, elimination, Grignard reagents, organolithium reagents, protecting groups, and reaction conditions for grades 11-12.
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Common reagents in organic synthesis help students predict how functional groups change during reactions. This cheat sheet summarizes the reagents most often used for oxidation, reduction, substitution, elimination, and carbon-carbon bond formation. It is useful because many organic problems depend on recognizing what each reagent does and choosing conditions that favor one pathway over another. The core idea is to connect reagent type, substrate, and product. Oxidizing agents such as and increase bonding to oxygen, while reducing agents such as and add hydrogen or remove oxygen-related bonds. Nucleophiles, bases, acids, and organometallic reagents each have predictable patterns, but solvent, temperature, and steric hindrance can change the major product.
Key Facts
- reduces aldehydes and ketones to alcohols, but it usually does not reduce esters or carboxylic acids under standard conditions.
- is a stronger reducing agent that converts aldehydes, ketones, esters, and carboxylic acids into alcohols after aqueous workup.
- oxidizes a primary alcohol to an aldehyde and a secondary alcohol to a ketone without normally overoxidizing the aldehyde to a carboxylic acid.
- or can oxidize primary alcohols to carboxylic acids and secondary alcohols to ketones under strong oxidative conditions.
- A Grignard reagent has the form and reacts with aldehydes or ketones followed by to form a new carbon-carbon bond and an alcohol.
- reactions are favored by strong nucleophiles, polar aprotic solvents, and unhindered substrates, and they occur with backside attack and inversion of configuration.
- reactions are favored by strong bases and require an anti-periplanar and leaving group arrangement for alkene formation.
- Acid-catalyzed hydration of an alkene adds and across the double bond in Markovnikov orientation, placing on the more substituted carbon.
Vocabulary
- Reagent
- A reagent is a substance added to a reaction to cause a specific chemical transformation.
- Oxidation
- Oxidation in organic chemistry usually means increasing bonds from carbon to electronegative atoms such as oxygen or decreasing bonds from carbon to hydrogen.
- Reduction
- Reduction in organic chemistry usually means increasing bonds from carbon to hydrogen or decreasing bonds from carbon to electronegative atoms.
- Nucleophile
- A nucleophile is an electron-rich species that donates an electron pair to form a new bond with an electrophile.
- Leaving group
- A leaving group is an atom or group that departs with an electron pair during substitution or elimination.
- Grignard reagent
- A Grignard reagent is an organomagnesium compound written as that acts as a strong nucleophile and base.
Common Mistakes to Avoid
- Using to reduce a carboxylic acid is wrong because is usually too mild for carboxylic acids and esters.
- Choosing in water or alcohol solvent is wrong because reacts violently with protic solvents before reducing the intended substrate.
- Expecting to turn a primary alcohol into a carboxylic acid is wrong because is commonly used to stop at the aldehyde stage.
- Ignoring substrate structure in reactions is wrong because tertiary substrates are too hindered for efficient backside attack.
- Treating every strong nucleophile as only a substitution reagent is wrong because many strong nucleophiles are also strong bases and may favor elimination.
Practice Questions
- 1 Predict the major product when is treated with followed by water.
- 2 How many moles of are needed if mole of can deliver hydride equivalents and of ketone requires of hydride?
- 3 A student has of benzaldehyde, , with molar mass . How many moles of benzaldehyde are available for reduction?
- 4 Explain why a bulky strong base such as often favors elimination over substitution in reactions with alkyl halides.