---
title: "Nucleophilic Addition | Inorganic Chemistry II"
description: "Nucleophilic addition is a reaction where a nucleophile attacks an electrophilic carbon, often in carbonyls or organometallic chemistry in Inorganic Chemistry II."
canonical: "https://fiveable.me/inorganic-chemistry-ii/key-terms/nucleophilic-addition"
type: "key-term"
subject: "Inorganic Chemistry II"
unit: "Unit 3"
---

# Nucleophilic Addition | Inorganic Chemistry II

## Definition

Nucleophilic addition is a reaction where a nucleophile bonds to an electrophilic carbon, most often a carbonyl carbon. In Inorganic Chemistry II, it shows up in organometallic reactions like Grignard additions.

## What It Is

Nucleophilic addition is the step where a nucleophile donates an electron pair to an electrophilic carbon and makes a new sigma bond. In Inorganic Chemistry II, you usually see it when an organometallic reagent adds to a polarized functional group such as a carbonyl, or when a carbon-centered nucleophile reacts with an electron-poor center in a coordination or synthetic pathway.

The reason this works is the same idea you see throughout organometallic chemistry: bond polarity creates reactivity. A carbonyl group has a partially positive carbon because oxygen pulls electron density toward itself. That makes the carbon a target for nucleophiles, especially strong ones like Grignard reagents or organolithium compounds, which behave as if the carbon attached to the metal is highly nucleophilic.

When the nucleophile attacks, the pi bond of the electrophile usually shifts to an atom that can handle the extra electron density, often oxygen in a carbonyl. That gives a tetrahedral intermediate or a closely related adduct. This is a big deal because it changes a flat, trigonal planar carbonyl carbon into a four-coordinate center, which is why nucleophilic addition is often discussed with 3D geometry and stereochemistry.

What happens next depends on the system. For a carbonyl plus a Grignard reagent, the first product is usually an alkoxide bound to magnesium, not the neutral alcohol yet. A later protonation or hydrolysis step gives the alcohol. That means the addition step and the workup step are separate, and if you miss that distinction, the mechanism looks more complete than it really is.

In organometallic chemistry, nucleophilic addition is one of the cleanest ways to form new carbon-carbon or carbon-heteroatom bonds. It is also a useful contrast with oxidative addition, because nucleophilic addition does not usually increase the metal’s oxidation state in the same way. Instead, the emphasis is on the nucleophile attacking an electrophilic atom and building up a new framework through electron-pair movement.

## Why It Matters

Nucleophilic addition is one of the main bond-making moves in organometallic chemistry, so it shows up whenever a reagent is being used to build a larger molecule from a reactive starting material. In a course like Inorganic Chemistry II, this is the kind of mechanism that connects metal-carbon bonding to real synthetic outcomes.

It also gives you a way to predict products instead of memorizing them. If you recognize a strong nucleophile such as a Grignard reagent and an electrophilic carbonyl, you can usually sketch the first addition product, identify the tetrahedral intermediate, and then finish the mechanism with protonation or workup. That skill transfers directly to reaction problems, mechanism questions, and lab writeups.

This term also sits at the intersection of structure and reactivity. Carbonyl polarity, nucleophile strength, and steric hindrance all affect whether the addition happens quickly and where the nucleophile can approach. So nucleophilic addition becomes a small but useful test of whether you can read 3D structure, electron distribution, and reaction conditions at the same time.

You will also run into it when comparing reaction types. It is a good checkpoint for telling apart addition at a carbonyl from substitution at a metal center, or from oxidative addition at a transition metal. Those differences matter a lot in organometallic mechanisms and catalysis problems.

## Connections

### Nucleophile

A nucleophile is the electron-rich species that does the attacking in nucleophilic addition. In organometallic chemistry, the nucleophile is often a carbon attached to a metal, which is why reagents like Grignard compounds can add to carbonyls so effectively. If you can spot the nucleophile, you can usually predict the bond that forms first.

### Electrophile

The electrophile is the electron-poor partner, and in nucleophilic addition the electrophilic atom is usually the carbonyl carbon. Its partial positive charge comes from the polarized C=O bond. Recognizing the electrophile helps you see why the nucleophile attacks there instead of at a less reactive site.

### Carbonyl Group

Carbonyl groups are one of the most common places where nucleophilic addition happens. The C=O bond is strongly polarized, so the carbon is easy for nucleophiles to attack. In your mechanism work, the carbonyl oxygen often ends up as an alkoxide after addition, which is why protonation matters in the final step.

### [Grignard Reagents](/inorganic-chemistry-ii/key-terms/grignard-reagents)

Grignard reagents are a classic example of strong nucleophiles used in nucleophilic addition. They add to carbonyl compounds and often give alcohols after acidic workup. In Inorganic Chemistry II, they are a good example of how a metal-carbon bond can behave like a carbon nucleophile.

## On the AP Exam

A mechanism question may give you a carbonyl compound and a Grignard reagent, then ask for the product after workup. Your job is to show the nucleophile attacking the carbonyl carbon, draw the tetrahedral alkoxide intermediate, and then add protonation to get the alcohol. If the question asks for reaction type, you should identify the step as nucleophilic addition, not substitution. On short-answer problems, you may also need to explain why the carbonyl carbon is electrophilic or why a certain organometallic reagent is reactive enough to add. In lab-based questions, this term often shows up when you interpret a synthesis step or justify why moisture-sensitive reagents have to be handled carefully.

## nucleophilic addition vs oxidative addition

Nucleophilic addition and oxidative addition both make new bonds, but they are not the same process. Nucleophilic addition is about an electron-rich nucleophile attacking an electrophilic atom, often a carbonyl carbon. Oxidative addition happens at a metal center and usually increases the metal’s oxidation state while adding two new ligands or fragments to the metal.

## Key Takeaways

- Nucleophilic addition is the attack of an electron-rich species on an electrophilic atom, usually a carbonyl carbon in this course.
- The first product is often a tetrahedral intermediate or alkoxide, not the final neutral molecule.
- Grignard reagents and organolithium compounds are classic nucleophiles because their carbon behaves as a strong electron donor.
- Protonation or hydrolysis often comes after the addition step and turns the intermediate into an alcohol or related product.
- If you can identify the nucleophile, the electrophile, and the workup step, you can usually predict the product correctly.

## FAQs

### What is nucleophilic addition in Inorganic Chemistry II?

It is a mechanism where a nucleophile attacks an electrophilic carbon and forms a new sigma bond. In this course, the most common example is addition to a carbonyl group by an organometallic reagent. The immediate product is often an alkoxide or tetrahedral intermediate.

### Why do Grignard reagents undergo nucleophilic addition?

Grignard reagents have a highly polarized carbon-magnesium bond, so the carbon behaves like a nucleophile. That carbon is drawn to electrophilic centers such as carbonyl carbons. After the attack, the product usually needs protonation to become a neutral alcohol.

### What happens after nucleophilic addition to a carbonyl?

The carbonyl pi bond is broken and the oxygen usually carries the extra electron density as an alkoxide. If the reaction uses an organometallic reagent, a later acidic or aqueous workup protonates that intermediate. That is why the isolated product is often an alcohol.

### How is nucleophilic addition different from oxidative addition?

Nucleophilic addition is driven by a nucleophile attacking an electrophile, usually outside the metal center. Oxidative addition happens at a metal and changes the metal’s oxidation state. If a problem gives you a carbonyl and a strong carbon nucleophile, think nucleophilic addition first.

## Related Study Guides

- [3.4 Synthesis and Reactions of Organometallic Compounds](/inorganic-chemistry-ii/unit-3/synthesis-reactions-organometallic-compounds/study-guide/gOpFLbkGlpdJr8Yq)
- [3.1 Introduction to Organometallic Compounds](/inorganic-chemistry-ii/unit-3/introduction-organometallic-compounds/study-guide/yrjdD54vXz4XGUlf)

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