Educational Materials for Organic Chemistry

CONJUGATE ADDITION WITH VARYING TIMES AND TEMPERATURES

This tutorial will allow you to explore the effect of changing the temperature and the amount of time in reactions involving conjugate addition. The reaction below is an example of conjugate addition by adding hydrogen chloride to butadiene at room temperature and for one hour. As you can see, two products are formed in unequal distributions. Here, 78% of 3-chloro-1-butene and 22% of 1-chloro-2-butene are formed. This product distribution will vary with temperature and time.

Discover for yourself which products predominate under selected conditions using the following reaction, which adds hydrogen bromide to 1,3-Butadiene.

Table 1: Adjustable Values

Previous TemperaturenoneCurrent Temperature-78 degrees C
Previous TimenoneCurrent Time1.5 hour

Table 2: Values Affected by Changes in Table 1

Previous Product Mixturesnone
Current Product Mixtures10% 1-Bromo-2-butene and 90% 3-Bromo-1-butene

Select conditions 1-6.

  1. Temp = -78 deg. C and Time = 1.5 hours
  2. Temp = -78 deg. C and Time = 3 hours
  3. Temp = -12 deg. C and Time = 1.5 hours
  4. Temp = -12 deg. C and Time = 4 hours
  5. Temp = 0 deg. C and Time = 1.5 hours
  6. Temp = room and Time = 1.5 hours




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This project was generously supported by a grant from the National Science Foundation.

Pages developed by Mary A. Dewan and Dr. Abby Parrill
Department of Chemistry
Michigan State University

These pages may be downloaded and linked from other pages freely for academic and educational purposes. Questions, problems, and errors should be sent to parrill@cem.msu.edu.