---
title: "Structure and Z/E configuration of 1-bromo-1-chloropropene"
subject: "Engineering Chemistry"
chapter: 9
key: "semester_2/engineering_chemistry:bromochloropropene-ze"
source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/bromochloropropene-ze
site: BCT Engineering
---

# Structure and Z/E configuration of 1-bromo-1-chloropropene

Engineering Chemistry · Chapter 9: Stereochemistry

- Asked in: 2067 Mangsir, 1 marks
- Video: [Draw the E and Z configuration of 2-bromo-3-chloro-2-butene](https://www.youtube.com/watch?v=4qEw07leVUM) — chemistNATE
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/engineering_chemistry/bromochloropropene-ze
- Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-9

## Question

Draw the structure and specify Z and E configuration of 1-Bromo-1-chloropropene.

## Short answer

1-Bromo-1-chloropropene, CH₃–CH=C(Br)Cl: higher priority Br over Cl at C1, CH₃ over H at C2. Br and CH₃ on the same side gives Z; on opposite sides gives E.

## Answer

1-Bromo-1-chloropropene is CH₃–CH=C(Br)Cl.
```text
   CH₃     Br                 CH₃     Cl
     \    /                     \    /
      C=C                         C=C
     /    \                     /    \
    H      Cl                   H      Br
      (Z)                         (E)
```
Priorities: at C1, Br (Z = 35) > Cl (Z = 17); at C2, CH₃ > H. Higher groups Br and CH₃ on the same side give **Z**; on opposite sides give **E**.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is 1-bromo-1-chloropropene?
   A. CH3-CH=C(Br)Cl
   B. CH3-C(Br)=CHCl
   C. CH2=C(Br)CH2Cl
   D. BrCH2-CH=CHCl
   Answer: A. Both Br and Cl are on C1. (Key point: Structure)

2. Which group is higher priority at C1?
   A. Cl
   B. Equal
   C. Br, since Z = 35 > 17
   D. Both are below carbon
   Answer: C. Higher atomic number. (Key point: Priority)

3. When is the compound Z?
   A. Br and CH3 on the same side
   B. Br and H on the same side
   C. Cl and CH3 on same side
   D. Br and Cl on same side
   Answer: A. At C2, CH3 > H. (Key point: Z)

## Related in Engineering Chemistry

- [Isomers of 3-bromo-2-butanol; racemization, resolution](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Abromobutanol-isomers-resolution) — Engineering Chemistry, chapter 9
- [Cis/trans isomers; structure of 2-chloro-3-methyl... [partly illegible]](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Acis-trans-chloromethylpentene) — Engineering Chemistry, chapter 9

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