Sciencemadness Discussion Board

Alcohol to alkane - Phytane synthesis from Phytol - HI/P

culturenout - 14-6-2019 at 17:42

Hi all,

I am trying to produce phytane from phytol which I have produced through saponification (base promoted ester hydrolysis) of chlorophyll.

This is how far I got:
HI and red phosphorous react as a strong reducing agent that will even reduce a primary alcohol like phytol. Even so, a primary alcohol is still a terrible reactant and I might have to heat the reaction and/or even pressurize it to maximize yield. However, ideally I would like to avoid pressurizing experimental vessels for fear of a huge mess. Obtaining reagents is not an issue, time and yield is.

I will hydrogente the product alkene from the HI/P reaction with a Pb catalyst to obtain my alkane, phytane.

I could not find a detailed experimental setup for this reaction or expected yield for a long-chain hydrocarbon online since information about using HI/P to produce meth (hey, you do you) is swamping the search results.

Help anyone?


[Edited on 15-6-2019 by culturenout]

TGSpecialist1 - 14-6-2019 at 22:02

Convert alcohol to halide then reduce with borohydride?

Chemi Pharma - 15-6-2019 at 02:28

Quote: Originally posted by TGSpecialist1  
Convert alcohol to halide then reduce with borohydride?


You'd better tosylate the alcohol with tosyl chloride in pyridine and reduce later with borohydride or KOtBu in DMSO. The yields are better.

Reducion of halides with borohydride only works with decent yields for primary and secondary iodides, in DMSO media. For bromides and chlorides I'd rather dehalogenate them with Zn and NH4Cl in THF with good yield.

Look at the papers attached.

Attachment: Dehalogenation with Zinc, NH4Cl and THF.pdf (60kB)
This file has been downloaded 285 times

Attachment: dehalogenation with sodium borohydride and DMSO.pdf (566kB)
This file has been downloaded 271 times

Attachment: Tosylates synthesis and elimination.doc (65kB)
This file has been downloaded 342 times

TGSpecialist1 - 15-6-2019 at 07:44

It would form an allylic halide which would probably be easier to reduce.

culturenout - 16-6-2019 at 19:22

Quote: Originally posted by Chemi Pharma  
Quote: Originally posted by TGSpecialist1  
Convert alcohol to halide then reduce with borohydride?


Reducion of halides with borohydride only works with decent yields for primary and secondary iodides, in DMSO media.


Thank you very much!

would a reduction of iodides with Super-Hydride solution (lithium triethylborohydride in tetrahydrofuran) result in decent yields?

Chemi Pharma - 17-6-2019 at 10:30

Quote: Originally posted by culturenout  
Quote: Originally posted by Chemi Pharma  
Quote: Originally posted by TGSpecialist1  
Convert alcohol to halide then reduce with borohydride?


Reducion of halides with borohydride only works with decent yields for primary and secondary iodides, in DMSO media.


Thank you very much!

would a reduction of iodides with Super-Hydride solution (lithium triethylborohydride in tetrahydrofuran) result in decent yields?


I think you don't need to spend a so expensive reagent like Super-Hydride to dehalogenate alkyl iodides. If you read the paper I brought above about dehalogenation with borohydrides in DMSO media you'll verify that sodium borohydride can do this work with good yields in the case of iodides. if you want to work with bromides and chlorides I recommend the other way, using Zn and NH4Cl in THF.