---
title: "Primary alcohol + HBr (SN2) Template | MolDraw"
url: https://www.moldraw.com/templates/alcohol-hbr-sn2/
description: "Primary alcohol + HBr (SN2) template: Butan-1-ol is protonated by HBr (from NaBr and conc. H₂SO₄) and bromide displaces water to give 1-bromobutane, with no…"
lang: en
publisher: Scidart Academy
generated: 2026-11-13
---
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# Primary alcohol + HBr (SN2) template

![Primary alcohol + HBr (SN2) template: Butan-1-ol is protonated by HBr (from NaBr and conc. H₂SO₄) and bromide displaces water to give 1-bromobutane, with no carbocation.](https://www.moldraw.com/templates/alcohol-hbr-sn2.webp)

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Butan-1-ol is protonated by HBr (from NaBr and conc. H₂SO₄) and bromide displaces water to give 1-bromobutane, with no carbocation.

## Mechanism step by step

Protonation makes water the leaving group; bromide then attacks the carbon from the back

1. **Protonation** – HBr protonates the OH group
2. **Backside attack** – Br⁻ displaces water in one step

## Key points

- OH⁻ is a poor leaving group; H₂O (after protonation) is a good one.
- Primary alcohols react by SN2: a primary carbocation is too unstable to form.
- Tertiary alcohols react by SN1 through the carbocation, fast even at room temperature (compare the Lucas test).
- PBr₃ or SOCl₂ convert alcohols to halides without strong acid and without rearrangement.

Drawn with 37 atoms, 7 arrows, 6 shapes – every one editable in MolDraw.

## Sources

- [Clayden, Greeves & Warren, Organic Chemistry, 2nd ed., OUP 2012, ch. 15](https://openlibrary.org/isbn/9780199270293) Textbook
- [Smith, March's Advanced Organic Chemistry, 8th ed., Wiley 2020, ch. 10](https://openlibrary.org/isbn/9781119371809) Textbook

## How to use this template

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## Frequently asked questions

### Is the Primary alcohol + HBr (SN2) template free?

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### Can I edit the Primary alcohol + HBr (SN2) template?

Yes. It opens as an ordinary MolDraw drawing, so every structure, arrow, label and colour can be changed, and you can add your own content around it.

### Is the chemistry checked?

Every structure is checked with RDKit and every curly arrow passes MolDraw’s electron-flow audit. The sources used are listed on this page.

### What is a curly-arrow mechanism template?

A ready-made drawing of a reaction mechanism in which curved arrows show where electron pairs move in each step. You can open it in MolDraw, change the substrate and reuse it.

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