What reagents would I have to use to convert a trans alkene into a cis alkene?

example: trans-3-heptene to cis-3-heptene

My thoughts: I feel as if I would use Br2/CCl4 first to create a dihalide, then possibly 2NaNh2 and finally a lindlar catalyst to end with a cis isomer?

Make the epoxide of the trans alkene with McPBA. Open with tributyl phosphine. This will intercept the Wittig mechanism (after rotation of the C-C bond bewteen the carbons baring the oxygen and phosphonium), and you will lose the phosphine oxide and form the cis alkene.

To convert a trans alkene into a cis alkene, you can use a process called cis-hydrogenation. Here's a step-by-step guide for converting trans-3-heptene to cis-3-heptene using this method:

Step 1: Perform halogenation using Br2/CCl4:
Add Br2/CCl4 to trans-3-heptene. This will result in the formation of a dihalide intermediate.

Step 2: Perform an anti-hydrogenation using 2NaNH2:
Add 2 equivalents of NaNH2 to the dihalide intermediate obtained from step 1. Ensure that this reaction is performed at low temperatures (-78°C to -33°C) as the NaNH2 reagent is a strong base. This anti-hydrogenation step converts the dihalide intermediate to a tetra-alkyl complex.

Step 3: Perform hydrogenation using a Lindlar catalyst:
Use a Lindlar catalyst (Pd/CaCO3 or Pd/BaSO4/PbAc2) to carry out hydrogenation of the tetra-alkyl complex obtained from step 2. This catalyst is selective, allowing the hydrogenation process to proceed without complete saturation, resulting in the formation of a cis alkene.

By following these steps, you should be able to convert trans-3-heptene to cis-3-heptene.

To convert a trans alkene into a cis alkene, there are different reagents you can use depending on the specific reaction and conditions you want to apply. One commonly used method is called the Lindlar reduction.

The Lindlar reduction is a hydrogenation reaction that selectively converts a solid trans alkene into the corresponding cis alkene. Here is a general procedure for converting a trans alkene, such as trans-3-heptene, into a cis alkene, like cis-3-heptene using the Lindlar catalyst:

1. Start with the trans alkene, trans-3-heptene.
2. Combine the trans alkene with a suitable solvent, such as ethanol or tetrahydrofuran, in a reaction flask.
3. Add the Lindlar catalyst, which consists of palladium on a calcium carbonate (CaCO3) and barium sulfate (BaSO4) support.
4. Hydrogen gas (H2) is then passed through the reaction mixture under controlled conditions (typically at room temperature or slightly higher).
5. The Lindlar catalyst selectively reduces the trans alkene to the desired cis alkene by using poisoned (deactivated) palladium, which prevents complete reduction to an alkane.
6. The reaction is monitored by gas chromatography or other appropriate analytical techniques to ensure the desired cis alkene is formed.
7. Once the reaction is complete, the solvent and excess hydrogen gas can be removed, and the cis-3-heptene can be isolated using standard organic chemistry purification methods.

It is important to note that the Lindlar reduction is limited to unfunctionalized trans alkenes. If there are functional groups present, alternative methods specific to the functional group might be necessary.

Remember to always consult reliable sources, such as organic chemistry textbooks or peer-reviewed literature, when planning experimental procedures to ensure the best and safest results.