The Periodic Table

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2:14 AM

@orthocresol It's a tight one with the rare-earths tag. When do you want to decide it? I am personally leaning now more towards the post by Brian (@hBy2Py) ... what is your takeaway?

Avatar Shiny

2:52 AM

Q: Orientation in Benzene Rings With More Than One Substituent

Why is it that the chlorination of 1-chloro-3-nitrobenzene 18 gives 1,4-dichloro-2-nitrobenzene 19 as the major product, 1,2-dichloro-3-nitrobenzene 20 as a minor product and 1,2-dichloro-4-nitrobenzene 21 is not formed at all? I know $\ce{-NO2}$ is a deactivating, meta-directing group and hen...

Regarding that question . Can chlorine form a double bond?

3 hours later…

Tanuj

5:31 AM

@orthocresol point noted ! :)

1 hour later…

user471651

6:37 AM

@orthocresol sorry will take care in future

1 hour later…

Jojostack

7:43 AM

@ orthocresol good point. Today I will revise the answer

@orthocresol I generally use Marvin which is good, I will give a try to chemdraw even If I'm a fan of opensource and I was searching for something different

3 hours later…

orthocresol

10:25 AM

@Martin-マーチン I am leaning towards @hBy2Py's suggestion, I think the deciding factor is whether we have sufficient question numbers for separate tags, and it seems like we do. And in any case, it will be in our long term interest to separate them. I'm not particularly convinced with the difference in reactivity argument. They are different, but so are the transition metals, yet we lump all of the TMs (3d, 4d, 5d) together.

Martin - マーチン

yeah, well, that's true

wasn't there the initiative to create a tag for coinage metals, to at least get rid of gold/silver/etc tags we might have....

orthocresol

10:53 AM

I don't know what advantage that would offer over simply nuking the tags.

Martin - マーチン

11:29 AM

don't ask me...

i guess they'll pop up from time to time...

2 hours later…

Jojostack

1:31 PM

@orthocresol solubility in water is an hint that there is a resonance and pi greek electrons works as an electron donors I can add a more detailed answer later

1 hour later…

hBy2Py

2:46 PM

@orthocresol I never had the patience to actually build things.

Plus, the model kit I had sucked. Never stayed together.

@orthocresol I'm not particularly convinced with the difference in reactivity argument. They are different, but so are the transition metals, yet we lump all of the TMs (3d, 4d, 5d) together. || This is a good point.

1 hour later…

orthocresol

4:10 PM

I have a feeling that it's simply that we have catchy names for the 4f and 5f blocks, but not for the individual 3d/4d/5d blocks.

Well, now more jobs for retagging: rare-earth-elements needs to be remapped to lanthanoids and we need to make actinoids.

Somebody can do that... soon(TM)

4 hours later…

orthocresol

7:55 PM

A: Classification/Nomenclature of aroma and flavour compounds - terpenes, aldehydes, and alcohols, etc

Perhaps by classification/nomenclature you are referring to odour descriptors. If I remember correctly I have already covered a similar question about possibility of defining smell, so I will extract relevant parts here: Odour descriptors and odour profiles Odour descriptors are the words that ...

Ah... cis-3-hexenol. Along with vanillin, it's the only thing in the lab which smells nice...

Zhe

@orthocresol Does it just smell like allyl alcohol?

oh, no, it's homoallylic

orthocresol

8:10 PM

I've no idea what allyl alcohol smells like

But cis-3-hexenol smells like freshly cut grass.

It's one of my starting materials for substrate synthesis

It was... I finished making those substrates.

Zhe

8:45 PM

@orthocresol That actually sounds disgusting... :/

Also, you just prompted me to learn about GLVs: en.wikipedia.org/wiki/Green_leaf_volatiles

cis-3-hexenal is pretty close to your alcohol... O.o

So, it is literally the cut grass smell

pentavalentcarbon

I love the smell of freshly-cut grass...at least, more than the act of cutting the grass.

Bounty Hunter

9:03 PM

Q: What does pO2 of blood mean and why do we use it?

I understand the basic Dalton's law of partial pressures in gases. Also, Henry's law of diffusion, says, the concentration of gas dissolved in a fluid is proportional to the partial pressure above it. So if we say that the pO2 of oxygenated blood is 100mm Hg, where is the free gas existing in e...

biochemistry solubility gas-laws

Zhe

9:35 PM

@orthocresol I like how we wrote the exact same thing basically in two different places...

Q: Diene electrophilic addition

What is the drawn product drawn here the major product? I thought the radical (intermediate) is more stabilized at a primary carbon than at a tertiary one.

radicals

orthocresol

And, I was the one in the wrong. I really need to try and cut this habit of answering in comments.

@Zhe Oh, I quite like the smell. There are certainly worse things. The worst so far is probably this alkynyl bromide:

Zhe

@orthocresol I don't know about that. I actually started typing a comment and realized it was getting long.

orthocresol

orgsyn.org/demo.aspx?prep=v92p0156

(see note 16)

> The bromoalkyne product has a very distinct smell and the checkers recommend that all manipulations (especially evaporations) of the material be performed in a well ventilated hood.

Zhe

Oh, ti's Yu-Pu!

I overlapped with him briefly

He was kind of an odd person...

orthocresol

In what way?

(I mean, I find that most people in the lab - myself included - are odd in one way or another...)