6
This is straightforward enough: The $\ce{NaOMe}$ deprotonates the $\ce{OH}$ group on $\ce{C}$5, the alkoxide then does an intramolecular nucleophilic attack on the ester to give the lactone. This is favoured because it is intramolecular and forming a [6]-ring. It is possible that they may be some ester exchange of the $\ce{tBuO}$ group with the $\ce{MeO}$ ...
5
The density of a substance depends on its molecular density and packing fraction (where you need to be consistent in definiting the molar volume in calculating both attributes).
However you are looking for a simpler explanation that gets the general trends right. Just looking at molecular mass is too simple—larger molecules have greater mass, but take up ...
4
Density is a macroscopic measurement so we should look for average properties spread over several molecules.
The average density of a liquid is not that much smaller than that of its solid ($\approx 0.9$, there are a v. few exceptions, water/ice, silicon, gallium, germanium, bismuth where it is greater) which means that the distance between molecules is only ...
3
"Spontaneous" means different things in different contexts
Your penultimate paragraph captures a key idea. The explanation for why this is right requires a recognition of the context of the term "spontaneous".
The context of the statement at the start of the question $\Delta G=\Delta H-T\Delta S$ is negative is thermodynamic stability. ...
3
Here is a possible route:
Start from the commercially available 2,6-dichloro-5-fluoropyridine-3-carboxylic acid (1). Form the Weinreb amide (2) via the acid chloride. React this with vinyl magnesium bromide to form (3). React the product with 1 eq of aniline in the presence of non-nucleophilic base to produce (4). Isolate this product and react with excess ...
3
The comments summarized the reasons well: the diazotization reaction for the initial structure would produce a mixture of $\alpha$-azo and $\beta$-azo compounds, which would give a mixture of products. Also, diazonium salts couple with activated aromatic systems. The diazonium salt shown would not couple with nitrobenzene, which is highly deactivating and ...
2
Here is the way how I got the product in my question:
2
Try to get samples of marble (pure calcium carbonate) in a marble mason workshop. Any piece of marble will do. Or try to find samples of ordinary calcareous stone (impure calcium carbonate), that can be found everywhere along the footpaths. Check if it is made of calcium carbonate by dipping them into some vinegar : it must produce bubbles if the stone is ...
2
First, a disclaimer: there is no shortage of opinion about what comprises physical or chemical changes.
This page is entitled Identifying Physical and Chemical Changes and is intended to help instructors guide STEM students on this topic.
You might find good ideas with low overhead in the Teaching Activities section such as these, quotes from the document:
...
1
The substrate in this reaction is an Acyl Chloride, which is highly susceptible to nucleophilic acyl substitution, more so than other carboxylic acid derivatives, so SN2 attack (as mentioned in the comments) is highly improbable. The mechanism for this nucleophilic acyl substitution is as follows:
With equilibrium constant $K_c >> 1$ favouring the ...
1
Yes, when bonds are formed, the hybridization can change in a carbon atom.
I think it’s important to remember something. Hybridization is not a real phenomena that occurs in reality. It is a model we use to simplify the complex bonding that occurs between atoms.
So, yes hybridization of the carbon will change, as it is not concrete and can change as bonds ...
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