Monday, October 30, 2023

Can you re-explain why nucleophilicity does not correlate with basicity under protic conditions? (Because the larger particle size decreases their basicity and nucleophilicity due to stabilization and increases nucleophilicity due to polarization. In protic solvents the basicity is suppressed, but nucleophilicity is not affected, so polarization overrides stabilization. Great question! I added it to our organic chemistry blog. - GS). 

Wednesday, November 2, 2022

 Can you clarify the differences between nucleophilicity (Nucleophiles change their ability to donate a pair of electrons in the process of the reaction due to polarizability. They usually attack carbon - GS)., basicity (Bases do not change their ability to donate a pair of electrons in the process of the reaction. They usually attack carbon - GS), and polarizability (Ease of separation of charges in the electric field, which makes the difference between bases and nucleophiles - GS)

Wednesday, October 5, 2022

Markovnikov rule

 For which reactions do we use markovnikov’s rule versus anti-markovnikov’s rule? (Regardless of the rule, the preferred reaction proceeds through the most stable cation or radical on the most substituted carbon. It requires the least substituted carbon of the C=C bond to be attacked. So, when the attacking particle is hydrogen (such as H+ in acid-catalyzed hydration or hydrohalogenation) or something that will become hydrogen later (Hg(OAc)2 in mercuration followed by reduction, the reaction goes by Markovnikov rule. If the least substituted carbon is attacked with something else (Br. in free radical hydrobromination) or Boron in hydroboration followed by oxidation, the reaction goes against Markovnikov rule - GS).

Tuesday, March 16, 2021

 How can you tell when a reaction goes through the meisenheimer complex or benzyne? (The Meisenheimer complex is formed only in the presence of a resonance acceptor in an ortho- or para-position to the leaving group. Otherwise the reaction requires a strong base, harsher conditions, and proceeds through benzyne - GS).

Thursday, October 22, 2020

 Can you explain in more detail the separation of enantiomers into diastereomers? (A mixture of enantiomers is treated with a chiral reagent to convert them to two new compounds, which have opposite centers from enantiomers and same centers from the chiral reagent, so they are diastereomers. Next, the diastereomers are separated and cleaved back into original enantiomers and the chiral reagent back. - GS).

Tuesday, April 28, 2020

What should we know regarding fluorescence? I recall discussing the topic in the past but am unable to find my notes regarding. (When a molecule absorbs the energy of light, it can cause a chemical reaction (photochemistry), or re-emit back as a light of different energy (fluorescence), or “wiggle out” by molecular vibrations to heat. Rigidity of a molecule reduces “wiggling out” the energy, which increases the efficiency of fluorescence. Therefore, we can control fluorescence by affecting the molecule by pH, presence of metals, DNA, etc. That is how many chemical sensors work. - GS).

Monday, April 27, 2020

E1 reactions are not stereoselective, so would the products be present in a racemic mixture like Sn1? (No. Unlike SN1, E1 does not produce a chiral center because the C=C bond is planar. - GS).