Sciencemadness Discussion Board
Not logged in [Login - Register]
Go To Bottom

Printable Version  
 Pages:  1  ..  17    19
Author: Subject: Synthesis of longer chain tertiary alcohols
oldtimer
Harmless
*




Posts: 12
Registered: 18-8-2008
Member Is Offline

Mood: No Mood

[*] posted on 2-1-2017 at 17:27


Where I live, 1-pentanol and "octyl alcohol" are easily available. I am however not sure, if the latter is 1-octanol or some branched isomer. 1-butanol I have in the lab.
I will try to prepare some 2-methyl-2pentanol, 2-methyl-2hexanol and 3-methyl-3-heptanol.

As to quantities: If I remember blogfasts posts correctly, he used about 5 .. 6 grams of alcohol for each of his potassium runs. 25 g should therefore be a quantity that allows a few of these experiments.
View user's profile View All Posts By User
Alice
Hazard to Others
***




Posts: 111
Registered: 11-5-2015
Member Is Offline

Mood: No Mood

[*] posted on 17-4-2017 at 05:30


In the meantime I had two new ideas about obtaining long chain tertiary alcohols.

My first idea was to alkylate raspberry ketone and perform a Grignard afterwards. The advtantage is to deal with solid products, thus easy purification compared to high boiling and badly crystallyzing liquids.

Second, cyclization of citronellol with an acid in order to obtain either the alkene with further addition of water or dihydro terpineol directly. A problem is to obtain citronellol. An alterternative synthesis is starting from citronellal, which needs to be reduced to citronellol first. A general problem is to identfy reaction products. The advantage is to avoid reducing an alkene compared to the previously discussed synthesis of terpineol followed by precious metal reduction to dihydro terpineol.

I think I'll try the raspberry ketone based synthesis first as I expect less pitfalls and the same iodoalkane can be used for both steps. Nevertheless this may take a while...

[Edited on 17-4-2017 by Alice]
View user's profile View All Posts By User
soniccd123
Harmless
*




Posts: 10
Registered: 20-1-2014
Location: Brazil
Member Is Offline

Mood: No Mood

[*] posted on 11-7-2017 at 13:51


Yesterday I was reading Semimicro and Macro Organic Chemistry by Nicholas Cheronis looking for sources on alcohol oxidation to carboxylic acids and something caugh my atention: "The use of permanganate with alcohols
which contain tertiary hydrogen (branched chains), as for example,
isobutyl alcohol, (CH3)2CHCH2OH, involves the danger of oxidation
in other parts of the molecules." (page 199). I looked into more information on the internet about this and, while little was found, two papers (on the end of the message) talk about the oxidation of tertiary hydrogens to hydroxyl groups.

Wouldn't be possible to oxidate the tertiary hydrogen on Isovaleric acid to 3-metil-3-hydroxybutanoic acid and then decarboxylate this to T-butanol?

Sketch of the reaction:

[bad img]http://imgur.com/a/HJL8i[/bad img]

Papers:
http://pubs.acs.org/doi/abs/10.1021/ja00705a642?journalCode=...
http://pubs.acs.org/doi/abs/10.1021/ja01501a033?journalCode=...
View user's profile View All Posts By User
12thealchemist
Harmless
*




Posts: 24
Registered: 1-1-2014
Location: The Isle of Albion
Member Is Offline

Mood: Gallous

[*] posted on 17-5-2018 at 08:44


I'm aware this thread hasn't been active for nearly a year, but I had an idea that may be worth considering before discarding as too much effort.
I was reading the potassium thread out of interest (the train of thought initiated by NurdRage's recent video on making sodium via that process) and was thinking about alternative tertiary alcohols. The proportion appears to be ~5 mol%, working from woelen's numbers on http://woelen.homescience.net/science/chem/exps/synthesis_K/...

On the basis of this, I started thinking about how one could avoid any side reactions, and possibly have a "perfect" catalyst. Tertiary alcohols are used so that α-elimination products cannot occur; ethanol forming acetaldehyde, isopropanol forming acetone. These then polymerise, and form organic gunk.
However, all these thus-far proposed tertiary alcohols do have β-hydrogens, and so could undergo elimination to form alkenes, thus deactivating the catalyst. One could use tertiary alcohols that do not have β-hydrogens, but one then ends up with things like tri(t-butyl)methanol or 1,1,2,3,3-pentamethylcyclohexan-2-ol, which are difficult and complicated to synthesise (and very expensive) for obvious reasons. What if one used a bridgehead alcohol, for example bicyclo[2.2.2]octan-1-ol? Elimination products cannot form to bridgeheads due the inherently strained nature of the product. Similarly, nucleophilic substitution reactions cannot occur.

After a bit of thought, I came up with this synthesis. I figured it would be feasible for the determined amateur.

Bicyclo[2.png - 174kB

From a bit of googling, it appears that the Birch reduction cannot be carried out on phenol itself, unfortunately, hence the need to protect the OH. I wonder if it is possible to combine the hydrolysis, Diels-Alder, and decarboxylation into a one-pot reaction, thereby speeding the process up considerably. I am aware that the last step, the reduction, uses palladium on carbon, an expensive reagent, but I've seen it mentioned as being used by other SM members, hence above claim of feasibility.
View user's profile Visit user's homepage View All Posts By User
 Pages:  1  ..  17    19

  Go To Top