Sciencemadness Discussion Board

Thiobenzophenone synth

Ormarion - 24-8-2021 at 10:50

Hello fellow chemist and welcome back for a new smelly adventure

Today i wanted to share a synth i just finished that gave a beautiful result: Thiobenzophenone

Little reminder: H2S is a silent killer, keep in mind it is nearly as toxic as HCN and it paralize your odor sensor over time, not smelling it doesn't mean it isn't here, alwaus keep some lead acetate test around of your apparatus and work in a well ventilated area under a air aspiration
For thiobenzophenone i haven't found much info so consider it not less dangerous than benzophenone itself if more

While getting lost on internet at work i found a protocol making it and as it was described as a bleu to purple compound i decided to give a try to the synth
The original procedure is from this site
http://orgsyn.org/demo.aspx?prep=cv4p0927
here my goal is to share the modifications i added to make it more doable by a amateur chemist

-I first started by measuring 25g of benzophenone i put in 125ml of dry ethanol (dry ethanol isn't needed, it is just cheap for me to get it)
-i then setup 2 generators
-The first one was an HCl gas made from NaCl and H2SO4 and the second one was the rest of my iron sulfide H2S generator when i made trithioacetone (i then switched it to a paraffin and sulfur generator as it work better for long periods of time)
- I cooled the flask to 10°c or so and started to bubble both gas in it via only one bubbler. There wasn't much change at the beginning, only slightly turned yellow
- i let it run for a few more dozen minutes and when i came back the whole reaction mixture turned a beautiful deep purple blue color. At this time it was getting late so i stopped the synth and let it in the fridge overnight
-Next day i continued to bubble both for a total of 2h and then i switched to H2S for around 5h. The solution got a deeper and deeper color until some blue cyrstals (looking like copper sulfate) started to precipitate
- At this point i was super happy and decided to stop here after i cooled it one last time to harvest as much product as possible. I filtered under vacuum in ambiant atmosphere and then immediatly put it in my dessicator under nearly perfect vacuum.

I haven't tested it yet or weight it but i would say i got around 15g from eye estimation. I will try to post news about the purity of it by IR spectrum and melting point in the followling week once school start back and that i can use their equipment

The product is described at not very air stable so i will run a test over some days to see if it does decompose

By the way beware, this compoun look beautiful but stink like H2S if not stronger

To finish i still have a deep blue solution where i will try to bubble more H2S to get as much product as possible


Here are some pictures, first of the final product drying unde vacuum second after some hours of H2S bubbling where you can still see benzophenone floating around and finally of the mixture after bubbling H2S and HCl gas at the beginning
Last picture is the ghetto setup i used for bubbling the H2S and cooling the mixture

Anyway hope you enjoyed and see you soon !

IMG_20210824_160153.jpg - 2.3MB

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IMG_20210816_163817.jpg - 1.8MB

IMG_20210824_150611.jpg - 2.3MB

DraconicAcid - 24-8-2021 at 11:25

An organic compound with that shade of blue?????? Amazing!

Ormarion - 24-8-2021 at 12:03

Thank you very much !

Ormarion - 28-8-2021 at 07:55

Little update after some days, the sample i left in air didn't changed much, except it dried cause it i hot at the moment in france. The crystals in the dessicator became partially transparent and made some yellow oil on the side wich stink like thiophene (i nearly not touched the dessicator and my fingers smelled for days). I think it is due to calcium chloride used as a dessicator, or maybe the perfume they put in it (it is from the hardware store).

On the other hand i have been able to crystallize 15 more grams from the mother solution, i won't dry them this time and try to see how they turn after some time in a closed container.

karlos³ - 28-8-2021 at 13:05

I love the blue, an organic blue :o

Much more impressive than indigo or its dibromo analogue purpur.

I wonder how it would perform as a pigment? Probably not well, but what would its benzhydrol analogue be in color?
Could you check on a little bit with a pinch of borohydride?

UC235 - 28-8-2021 at 13:26

Quote: Originally posted by karlos³  
I love the blue, an organic blue :o

Much more impressive than indigo or its dibromo analogue purpur.

I wonder how it would perform as a pigment? Probably not well, but what would its benzhydrol analogue be in color?
Could you check on a little bit with a pinch of borohydride?


It fairly easily oxidizes in air to benzophenone and sulfur. The blue color is the result of electrons being excited from the pi bond into a pi antibonding orbital in the thioketone. The reduced product will be as colorless as benzhydrol.

Ormarion - 28-8-2021 at 13:32

I can always try but i think UC235 is right

karlos³ - 28-8-2021 at 14:23

Sorry stupid me, I just intended to skim through the thread and then saw the color and reacted like a magpie... without actually knowing what I was talking about :o

I had actually thought about a benzophenone analogue with 2-thiophene groups instead of, well, a thioketone... insert the blushing smiley we don't have here....
Sorry, the color, and me not reading, I'll keep my mouth shut :o

I actually made two aminoketones from 2-propanoylthiophene and thats probably why I thought about a 2-thiophenylketone instead of a thioketone...

[Edited on 28-8-2021 by karlos³]

Ormarion - 29-8-2021 at 02:19

I recently got thiophene but i am not that experimented in retrochemistry, if you find me a protocol to test it i would definitely give it a try !

wg48temp9 - 30-8-2021 at 15:45

Quote: Originally posted by Ormarion  

Little reminder: H2S is a silent killer, keep in mind it is nearly as toxic as HCN and it paralyze your odor sensor over time, not smelling it doesn't mean it isn't here, always keep some lead acetate test around of your apparatus and work in a well ventilated area under a air aspiration


I recently watched a CSB safety video about a H2S accident that killed an oil worker and his wife when she went to find out why he had not come home.
It surprised me that they had both ignored the smell that I would have assumed was very intense and that both had presumable been overcome before they were able to leave the area.
So the above warning is important.

https://www.youtube.com/watch?v=jh2HWT8gPeY

PS:Yes that thiobenzophenone is interesting and a colorful compound. I may attempt the synthesis using phosphorous sulphide.

Bmoore55 - 30-8-2021 at 17:29

This is gorgeous! I am going to have to try this one myself. Great work!

Ormarion - 31-8-2021 at 03:04

wg48temp9 i recently learned that apparentlty H2S is like HCN, not everybody have the gene to smell it. Maybe this explain why, in any case i know i can smell both (you dont wanna know how for the cyanide ^^")

Ormarion - 6-9-2021 at 23:11

Little update on the solution, after staying in the freezer for a week it slowly lost it's blue color and the left crystals started to melt in a blue goo as described in the initial protocol.

Fery - 26-12-2021 at 09:26

Hi Ormarion,
here the blue oil mentioned in literature:
https://library.sciencemadness.org/library/books/Weygand_and...

Quote:
page 649
Baumann and Fromm [403] found that acetophenone gives,
not only the trimer, but also the monomeric thioketone as an unstable blue
oil from which the trimer is formed by pyrolysis.
[403] E. Baumann and E. Fromm, Ber. Deut. Chem. Ges., 28, 895 (1895).