Alkyne Reduction - Hydrogenation, Lindar's catalyst, Dissolving Metal Reduction - cis/trans alkenes

leah4sci.com/alkyne Presents: Alkyne Reduction - Hydrogenation Reaction and Mechanism
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This video walks you through the 3 types of alkyne reduction reactions including alkene to alkane, and alkyne to cis and trans alkene using a Lindlar Catalyst and Dissolving Metal Reduction including a step by step walkthrough of the radical reduction mechanism using Na NH3.
In this video:
[0:06] Alkyne Reduction Reactions
[2:11] Mechanism for catalytic alkyne reduction
[5:09] Lindlar's catalyst to cis Alkene
[10:00] Dissolving metal reduction to trans alkene
Catch the entire Video Series Along with the Alkyne Practice Quiz (coming soon) and Cheat Sheet on my website at leah4sci.com/alkyne
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[@laelblass9560]

Leah4Sci does it again! I have been struggling to understand this for a week and now 15 minutes later I finally do! Thank you!

[@Leah4sci]

Wonderful! You are so very welcome!

[@hassanmarwat5723]

I didnt know that how a lone pair forms bond with hydrogen But u explained that the nitrogen N takes both the electrons involved in N-H bond so hydrogen is not left with any electrons thats why it forms a bond with lone pair.... Really appreciate that 😊

[@Leah4sci]

You're very welcome!

[@nathanm8234]

Thank you very much for the clear explanation. Subscribed!

[@Leah4sci]

You're welcome! Thanks for the sub!

[@AR-vb4xy]

These videos are gold!

[@Leah4sci]

Thanks!

[@PunmasterSTP]

Or are they Pt, Pd or Ni? 😎

[@wumaster1]

I like how you used different colors to help visualize the movement of the electrons and atoms. That's why I now follow your habit and use colored pens to take notes. 😃

[@Leah4sci]

I love using color; it find it so much easier to see and understand. So glad it's helping you, too!

[@hassanmarwat5723]

Thank you teacher 😊 it was very helpful

[@Leah4sci]

You're very welcome!

[@mahanteshramannavar8242]

Mam which one can undergo addition reaction most readily; Alkene Or Alkyne?..

[@Leah4sci]

Thanks for asking. Alkynes undergo hydrogenation reactions and nucleophilic addition reactions more readily than alkenes.

[@TanishqSrivastava]

Wonderfully explained.. thanks

[@Leah4sci]

You're so welcome!

[@ab_khanayy]

love this!!!! Understood it so easily thank youuu :)

[@Leah4sci]

You're so welcome!

[@cedricksikuku3011]

You are the best tutor , I like the way you teach

[@Leah4sci]

I appreciate that, thank you! I'm so happy to help.

[@watsoncrick6071]

Hey, your videos are awesome. I am a bit confused over why we use palladium or nickel for every reducing reaction. Can you please help me out? :)

[@Leah4sci]

You can use other metals too

[@user-xx5ce5rn7x]

Hello ma'am, I am preparing for NEET Examinations (Indian entrance examination to enter medical colleges), organic chemistry plays a very vital role and you made me understand the topic easy... Thanks

[@Leah4sci]

You're very welcome!

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Thank you so much for this information 👍👍👍👍👍❤️❤️❤️❤️❤️

[@Leah4sci]

You're so welcome!

[@Ryan-fi2ul]

in what situation would you use 2H2 ?

[@Leah4sci]

Great question! You use 2 moles of H2 as a reagent when performing a catalytic reduction of an alkyne to an alkane. This is because completely reducing all of the triple bonds in the sample to single bonds would require a 2:1 ratio of H2 to alkyne.

[@mattpatrocinio7578]

Thx for these videos ur better than my professor

[@Leah4sci]

Glad you like them! I'm always happy to help.

[@kinzazafar336]

very well explained

[@Leah4sci]

Glad you think so!

[@derrickdot2298]

What of in a situations where you nees to have an alkene with 2 double bonds? How does it go

[@Leah4sci]

How does the mechanism go? Unfortunately, I don't offer tutoring over social media. For help with questions like this and more, I recommend joining the organic chemistry study hall. Details: leah4sci.com/join or contact me through my website leah4sci.com/contact/

[@casualcasual1234]

Hello so overall reaction of trans alkene formation consumes 2 eqv Na & 2 eqv NH3?

[@Leah4sci]

Yes, per every one mole of alkyne that is reacted.

[@casualcasual1234]

@@Leah4sci oh thanks a lot

[@calenolsen]

3:35, where do the blue hydrogens come from?

[@Leah4sci]

Hydrogen is required for this reaction, typically added in the form of H2 gas. H2 will first bind to the metal catalyst.

[@star-sq9mc]

Amazing explanation❤ I felt problem in understanding reaction of na in liq ammonia

[@Leah4sci]

Glad you found it helpful, what about the reaction of na in liq ammonia did you find difficult to understand?

[@hannahk6117]

why does H2/Pd fully reduce the alkyne chain ??? why cant it stop at an alkene

[@Leah4sci]

The short answer: It is too strong of a reducing agent to stop at the alkene. We do have other methods of getting the alkyne to an alkene, namely H2 with the Lindlar's catalyst. Make sure to take a look at my redox cheat sheet at leah4sci.com/orgo-oxidation-reduction-reactions-study-guide-cheat-sheet/

[@tamjeedzawan6554]

QUEEN part 3

[@Leah4sci]

:)

[@narasimhagosu465]

Good video and Can you give me some videos on reduction of acids

[@Leah4sci]

Thank you. PLease check my channel

[@gauravbhakar7207]

what if 1 eqv of h2 PD?

[@Leah4sci]

Discussed in the video, watch it again

[@tysonsmat9918]

Instead of radical breaking, can we not visualize that the single electron attacks the alkyne carbon from the back (antibonding orbital) in SN2 fashion pushing the lone pair in the oppsite side to adjacent carbon as the original carbons bonding orbital changes to anti bonding one. In short a SN2 attack by a single electron on alkyne leading to trans lone pair - radical alkene intermediate.

[@Leah4sci]

This is too complex of a question for a KZbin comment. I stand by the accuracy of the mechanism in this video. If you would like to ask further questions, draw your proposed mechanism and send it to me through my website, along with your question, at Leah4sci.com/contact

[@KRISHNENDUJANA24]

Yeah trans radical is more stable but how can a double bond rotate ?

[@Leah4sci]

The double bond is not rotating. It’s more of a question of where the electron cloud containing the radical will gravitate. Non-bonding electrons (like the radical) are not tied down in space. According to the rules of VSEPR theory, it will choose to distance itself from the newly-formed lone pair as much as possible. Thanks for watching and asking!

[@PunmasterSTP]

Dissolving metal reduction? More like "Delightful videos; thanks for them!" 👍

[@Leah4sci]

Glad you like them!

[@PunmasterSTP]

@@Leah4sci For sure; they’re hydrogenawesome!

[@mobalegend3805]

if alkenes can be reduced to alkane does alkanes can be reduced to alkens?

[@watsoncrick6071]

alkanes can't be reduced...reduction is addition of hydrogens.. there's no more space in alkanes to add some more hydrogens.

[@Leah4sci]

Agree with the other comment. Alkanes cannot be further reduced. There is no position for additional hydrogens to be added.

[@anissabahkani2882]

Amazing explanation!

[@Leah4sci]

Glad it was helpful!

[@hajarrayhanaelaqil1988]

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[@Leah4sci]

Wow, thanks!

[@hajarrayhanaelaqil1988]

@@Leah4sci my pleasure

[@hwiatslgeord2887]

What is the exact composition of lindlar reagent

[@Leah4sci]

Its primary make-up includes palladium metal. However, its composition is not required knowledge in most orgo classes. As long as you know WHAT the Lindlar catalyst does and what product it would create in a given reaction, you should be in good shape.

[@hwiatslgeord2887]

@@Leah4sci thanks 😊

[@abidaliajiz]

Great 👍

[@Leah4sci]

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A million dollar video

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[@Leah4sci]

Glad you liked it, thanks for watching!

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Queen.

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[@Leah4sci]

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[@Leah4sci]

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[@Leah4sci]

I'll take that as a compliment :)