PrimoPyro (Hive Prodigy)
11-03-02 06:26
No 375947
      Triphenylphosphine Synthesis?  Bookmark   

I've searched Google, Scirus, and OrgSyn, and haven't found much of anything regarding any traditional methods to synthesize triphenylphosphine.

So I wonder, just how is this compound usually made? From elemental phosphorus somehow? From PX3? Could someone please tell me how triphenylphosphine and trialkylphosphines are synthesized?

Thank you.

(Hive Bee)
11-03-02 12:18
No 375990
      Triphenylphosphine synthesis  Bookmark   

This patent was found on Espacenet.

Process for the preparation of organic phosphines
Patent GB944062

Phosphines are prepared by reacting in an inert organic solvent (a) elemental phosphorus, (b) an organometallic compound RLi or RMgX where X is halogen and R is unsubstituted or substituted C1-12 alkyl, cycloalkyl or unsubstituted or substituted aryl, said substituents being halogen or C1-6 alkoxy and, if desired, (c) an alkyl halide, and, essentially when an alkyl halide is not present and optionally otherwise, hydrolysing the reaction mixture with water or dilute mineral acid when the reaction is completed. Temperatures of 0-150 DEG C. may be used. Primary, secondary and tertiary phosphines may be prepared and if molar ratios of reactants of the order 2(RMgX):1(P4):2(alkylhalide) are used, the product is stated to be a cyclotetraphosphine. The reaction mixture in Example V is treated with LiAlH4 before hydrolysis. Products prepared in examples are: phenylphosphine, diphenylphosphine, triphenylphosphine, butylphosphine, dibutylphosphine, tributylphosphine, naphthylphosphine, dinaphthylphosphine, trinaphthylphosphine, 4-methoxyphenylphosphine, 4-fluorophenulphosphine, octylphosphine, dioctylphosphine, trioctylphosphine, cyclohexylphosphine, dodecylphosphine, butylphenylphosphine, dibutylphenylphosphine, butyldiphenylphosphine, butyl (1-naphthyl) phosphine, butylbis (1-naphthyl) phosphine, dibutyl (3-trifluoromethylphenyl) phosphine, butylbis (3-trifluoromethylphenyl) phosphine, dibutyl (4-methoxyphenyl) phosphine, butylbis (4 - methoxyphenyl) phosphine, dibutyloctylphosphine, butyldioctylphosphosphine, hexyldimethylphosphine, dihexylmethylphosphine, butyl 4-fluoro-phenylphosphine, butylbis (4-fluorophenyl) phosphine, dibutyl 4-fluorophenylphosphine, cyclohexyldihexylphosphine, dicyclohexylhexylphosphine, tridodecylphosphine, dipentylpropylphosphine, dipropylpentylphosphine, trihexylphosphine, dimethyl 6-methoxy - 2 - naphthylphosphine, bis (6-methoxy - 2 - naphthyl) methylphosphine, and butylbis (3-trifluoromethylphenyl) phosphine.ALSO:Naphthalene and 1-butylnaphthalene are among the products when white phosphorus is added to an ethereal solution of 1-naphthyllithium and butylbromide obtained from butyllithium and 1-bromo-naphthalene (Example XXIII).

I hope this will help.

Life without chemistry would be a mistake.
(Hive Prodigy)
11-03-02 23:36
No 376138
      Thanks  Bookmark   

Thank you demerol, that was helpful. smile

I didn't know it required the use of organometallics. No wonder Ph3P is so expensive.

(Hive Bee)
11-09-02 22:16
No 378159
      Somebody was also curios  Bookmark   

about this reagent, but looking at that longwinded preparation, it seems diversion would bee easier.
An alternative (I'm assuming you want to make an ylide?) would be triethyl phosphite.
You can react that with a alkyl halide in presence of base to make a tetralkyl phosphonate (I think) it is called the Horner variation of the wittig RXN.
I.E. Wittig-Horner reaction which is touted as easier to perform, than the wittig rxn.
(Master Whacker)
11-09-02 22:55
No 378169
(Rated as: excellent)


Spisshaks advice to use triethyl phosphite instead of triphenylphosphine is very sound indeed.  The Horner modification of the traditional Wittig reaction is superior for several reasons.  A few of them are cost, yield and labor.  Triethyl phosphite is relatively cheap and easy to work with when compared to the traditional Wittig reaction using triphenyl phosphine.  Have you ever tried to isolate a solid product from the resulting triphenylphosphine oxide from a traditional Wittig?  If not, I can tell you from first hand experience it can be a nightmare.  Triphenylphosphine oxide can be a serious pain in the ass to separate from many chemicals- we had to use a custom-made continuous solvent extractor to get a respectable yield during the workup, and some Triphen.Phos. oxide would invariably be carried over during the extractions leaving us with a slightly contaminated product that could only be totally purified via filtration through a large amount of EXPENSIVE alumina.  The Horner modification eliminates the extravagant workup and yields increased by 10-15% too!  The secret to getting amazing yields with the Horner rxn. is to use a LARGE excess of    K-tBuO (at least 3-4mol excess) as the base.  This little secret worked for us on every substrate we used.  Our yields never dropped below 85% and were often over 90% with this Horner modification!
(Hive Prodigy)
11-09-02 22:58
No 378170
      Very True  Bookmark   

The end purpose is indeed for ylides/phosphoranes. I would not know where to begin in any "diversion" attempt. For me there are but two options: Purchase, and synthesis. It is quite expensive to buy, and even if the synthesis required elemental phosphorus and grignard reagents, I still think that such a synthesis would be cheaper than purchasing an identical quantity of triphenylphosphine.

I did think of using triethylphosphite as a substitute, but doesn't the Horner variation have lower yields? That's not an important enough detriment to make the use of triphenylphosphine necessary, I know.

But I am interested in triphenylphosphine for other reactions as well, such as its reaction with organic azides to form (I dont know how to name it so here's a formula) species described as R'-N=PR3, and this species reacts with epoxides to give aziridines, theoretically making 1,2-dimethylaziridine, the object of my desire, possible from the very available chemical propylene oxide. The only problem: the azide needed would be methyl azide, which is explosive. Hope these reactions don't get too hot. tongue

More than anything I was curious because I couldnt seem to find a synthesis anywhere, which I found odd. Why is this chemical so expensive? Does it require special purification procedures? It appears to be very reactive to a wide variety of compounds.

And I was curious because say someone had magically come into posession of a large lot of phosphorus, and had zero interest in HI reductions of ephedrine. What can phosphorus be used for??? There must be some very interesting organophosphorus chemistry, and I started looking and it led me again and again to triphenylphosphine.

What other cool things can be done with phosphorus? (any color)

(Hive Prodigy)
11-09-02 23:02
No 378171
      Wow  Bookmark   

Ok my last post was written before Ritter posted, so I hadn't seen that.

I see that my notion on yield was incorrect. Ritter, VERY interesting, I didn't know that triethylphosphite had such provocative attributes. I know Im asking for a lot, but can EtO3P be made cleanly from P as the starting material?

I know that phosphorus trioxide will react with ethanol, but is there another reaction?

(Hive Bee)
11-10-02 01:17
No 378202
      This reaction the ritter speaks of  Bookmark   

Would be ideal for making Alpha-ethylstyrene from propiphenone.
Which is a convenient prodine precursor, if you like narcotics.
I Know I Do.