Thiamin diphosphate (TPP), a derivative of vitamin B 1 required for glucose metabolism, is a wea

Thiamin diphosphate (TPP), a derivative of vitamin B 1...

Key Concepts

Molecular Structure Analysis and Functional Groups

Analyzing the molecular structure involves identifying the different functional groups and electronic environments present in the molecule, such as the sites of potential deprotonation. Recognizing these features allows for a targeted approach in assigning formal charges, particularly in complex molecules where functional groups like the thiazolium ring and diphosphate moieties influence the electron distribution upon deprotonation.

Formal Charge Determination

This concept involves calculating the charge on an atom within a molecule by comparing the number of valence electrons on the neutral atom with the electrons assigned to it in the molecule. The standard formula—valence electrons minus the sum of nonbonding electrons and half of the bonding electrons—allows one to systematically assign formal charges to different atoms, which is crucial for understanding reaction mechanisms and the stability of products in chemical reactions.

Acid-Base Chemistry and Deprotonation

In acid-base reactions, deprotonation refers to the loss of a proton (H?) from a molecule, which typically results in the formation of a negatively charged species. This concept is key in understanding how a weak acid, such as TPP, behaves under basic conditions, leading to modifications in the electron distribution and consequently the formal charges on the atoms that participate in the reaction.

Transcript

00:01 So they want us to write in all of the formal charges to the appropriate atoms in tpp and its deprotinated product.

00:13 So the only difference in between these two structures is going to be this hydrogen right here that they highlight in red and us having it removed to form that loan pair there.

00:24 So everything else, once we find the formal charge, we can just transfer it over.

00:30 And i forgot to put a double bond right there.

00:32 That nitrogen.

00:36 Now, let's see.

00:39 So normally, carbon has four bonds to it when it's neutral.

00:50 Oxygen normally has two bonds and two lone pairs.

01:00 Phosphorus, so this is one of those weird ones.

01:04 So i'll just say this normally has five valence electrons.

01:10 Sulfur is normally in the same case as, oxygen and nitrogen normally has three bonds and one lone pairs.

01:23 So this is just kind of a quick way to kind of weed out what is going to have a charge and what isn't.

01:29 So let's go ahead and draw on all of our loan pairs and everything.

01:33 So remember we want to at least have eight for everything.

01:37 So these oxygens with the double bonds, they already have two bonds.

01:40 So they need two lone pairs.

01:41 These oxygens over here are going to have three lone pairs since they only have one bond and these ester or these phosphorous phosphor ester linkages right here which are the oxygen going in between the phosphoreses are going to have two lone pairs because they both have two bonds now let's figure out the charges on these before we move on so the double bonds and the ester linkages are going to be okay because they have two bonds and two lone pairs, which would be six electrons.

02:20 They're valence, so that works out.

02:22 But now these oxygens on the outside with only one bond, all of these are going to have negative charges on them.

02:31 Since, notice that they have just seven, or they have seven valence electrons.

02:39 Oxygen normally has six, so that's one more.

02:43 Or you can think about it is it normally wants two bonds and two lone pairs, but it accepted a lone pair, so it would have more electrons than it normally has.

02:53 So we have those...

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