Good catch! Yes that is correct, our apologies for the mistake, we'll have this fixed.

Good catch! Yes that is correct, our apologies for the mistake, we'll have this fixed.

Thank you for letting us know, we will fix this 👍

You'll find the chart with the electron and molecular geometry tables as a downloadable pdf under the description of the video. We don't have downloadable lecture slides at this time due to copyright reasons but we are looking into ways to add more downloads on videos. For now we are adding important templates and charts as downloads and you'll find our practice exams and study with us series with downloadable pdfs. 

Thank you for your feedback, we appreciate it! 

Thank you for bringing this to our attention, we will look into this. Several of our videos have captions but some of our older ones do not. We are working on fixing that. So sorry about that! 

Were you referring to the example at timestamp 15:17 ? For this we were showing all the possible fragments which included the CH₃⁺ , notice that the fourth fragment shows that variation of the longer carbon chain as the radical and the methyl being the carbocation now. This is really just to show all the possible fragments and values that you'll see in the mass spectrum data. 

If a CH₃ group breaks off, and the CH₃ keeps the charge, that means the other fragment became the neutral radical. That may seem strange since CH₃⁺ is not a very stable carbocation.Fragmentation doesn’t always favor the most hyperconjugated carbocation.

Sometimes, a methyl shift or cleavage happens simply because it’s energetically favorable or statistically more likely, even if it forms a less stable carbocation.

So even if the longer chain could form a more stable carbocation, the fragmentation mechanism may have favored the methyl group carrying the charge.

Great Question! I recommend watching these videos, they will help you understand how to approach these types of questions. The first video has multiple practice problems, the last question is on answering questions with IR, H NMR and C NMR and Mass Spectrometry. 

Study With Us: Identifying Unknown Compounds Using IR and NMR Spectroscopy and Mass Spectrometry 

Practice Problem: Determining the Identity of a Compound (C8H14) Using IR and HNMR

Practice Problem: Finding the Structure of a Molecule Using IR, NMR, and MS

The below video has a worksheet:

Study With Us: Ranking Acidity, Using pKa, and Drawing Arrows in Acid-Base Reactions

As does this other practice exam:

Practice Exam: Structure, Bonding, Acids and Bases

We do have more practice problems here and we'll be adding worksheets shortly to these:

Practice Problem: Identifying the Most Acidic Proton in a Molecule

Practice Problem: Which of the Following Is the Strongest Acid?

Practice Problem: Which of the Following Is the Strongest Base?

Practice Problem: Listing Alkynes and Alkenes in Order of Increasing Acid Strength

Chemmunity Team 

"Sharpless reagents" usually refers to the set of reagents used in Sharpless asymmetric reactions, invented by K. Barry Sharpless. The two most famous ones are:

Used for: Epoxidizing allylic alcohols (alkenes with an -OH on the adjacent carbon)

Reagents:

Titanium(IV) isopropoxide (Ti(OiPr)₄)

(–)- or (+)-diethyl tartrate (DET) → gives the stereoselectivity!

tert-Butyl hydroperoxide (TBHP) → the oxidant

Product: Chiral epoxide with high enantioselectivity→ Which enantiomer you get depends on whether you use (+)-DET or (–)-DET

Used for: Converting alkenes to vicinal diols (2 adjacent OH groups), enantioselectively

Reagents:

OsO₄ (osmium tetroxide, catalytic)

A chiral ligand like (DHQ)₂PHAL or (DHQD)₂PHAL

NMO (or another co-oxidant)

Product: A chiral diol with predictable stereochemistry→ Again, you choose the enantiomer using the right ligand