Uhhm, this may seem a bit pathetical, but my great interest in the subject gently forces me to post this nonetheless:
I want to hear peoples voices on failed and/or successful attempts or some detailed 2nd hand writeups on preparations of the title compound (best without using P2O5) cause it is another important puzzle-piece in the picture showing the clandestine way to EtNO2 / propiophenones.
Post 377568 (https://www.thevespiary.org/talk/index.php?topic=9030.msg37756800#msg37756800)
(FriendlyFinger: "I want to make proipiophenone", Methods Discourse)
Post 463377 (https://www.thevespiary.org/talk/index.php?topic=6375.msg46337700#msg46337700)
(psyloxy: "alpha-bromopropanoic acid - a final word ?", Chemistry Discourse)
Notes for it's preparation can be found in
Post 398338 (https://www.thevespiary.org/talk/index.php?topic=9688.msg39833800#msg39833800)
(Aurelius: "repost", Methods Discourse)
Post 412338 (https://www.thevespiary.org/talk/index.php?topic=9688.msg41233800#msg41233800)
(Aurelius: "Ulmann's Polyphosphoric acid", Methods Discourse)
Post 362697 (missing)
(starlight: "not sure as yet", Newbee Forum).
I know there's lot's of refs that I could all read myself but I simply don't have easy access to them, thanks for your undestanding.
--psyloxy--
Structure and Properties of the Condensed Phosphates. I. Some General Considerations about Phosphoric Acids
John R. Van Wazer, Karl A. Holst
J. Am. Chem. Soc. 72, 639-644 (1950) (https://www.thevespiary.org/rhodium/Rhodium/pdf/polyphosphoric.acid.pdf)
(https://www.thevespiary.org/rhodium/Rhodium/pdf/polyphosphoric.acid.pdf)
May be prepd by heating H3PO4 with sufficient {P2O5} to give the resulting product an 82-85% P2O5 content
For calculating the needed amounts, assume that 85% H3PO4 is a mixture of 15 wt% H2O and 85 wt% of a 19:81 mixture of H2O/P2O5 - This as phosphorous pentoxide and water reacts to form phosphoric acid as follows:
3 H2O (18g/mol) + 2 P2O5 (142 g/mol) (https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_docs/000464600-file_mxzy.gif) 2 H3PO4 (169 g/mol)
We can then calculate that 85% H3PO4 is equal to a mixture of 15 + (0.85 * 19) = 31.15 wt% H2O and 0.85 * 81 = 68.85% P2O5
Now simply add enough P2O5 to make a 82-85% solution and heat as in the article linked above.