(Stranger)
12-31-03 01:12
No 479855
(Rated as: excellent)
Substituted Mandelic acids
Uses of Mandelic acid and its phenyl substituted derivants:
1. Decomposition to the corresponding benzaldehydes w/ HNO3
as in: Post 391475 (pHarmacist: "One More piperonal patent, High-yielding", Novel Discourse)
This is a good alternative to aromatic formylations.
2. Reduction to the corresponding Phenylacetic acids
This can be done w/:
- HI/P as in ../rhodium /phenyla
or: Patent US4590295 for 4-OH-PAA (from phenol in one pot)
For 4-OH-PAA: Patent US4198526
- Cr(III)Cl3 / Zn w/ 97% yield (!)
- H3PO2 (Hypophosphorous acid)
- Catalytic hydrogenation
3. The synthesis of novell Pemoline analoges of phenetylamines, from mandelic acid esters.
According to ../rhodium /pemolin
(this is a wery INTERRESTING possibility!)
Synthesis of substituted Mandelic acids:
I.) Reaction of substituted benzenes w/ Glyoxylic acid:
A. w/ aquaeous Glyoxilic acid in warious solvents. Substrate: 1,2-Methylenedioxybenzene (Benzodioxole), in GAA, yield of 1,2-MD-mandelic acid is 95%
Patent EP1229031
Similarly in: Post 391475 (pHarmacist: "One More piperonal patent, High-yielding", Novel Discourse)
B. w/ aquaeous Glyoxilic acid in the presence of a tertiary amine and a trivalent metal catalyst.
Patent US5354897
C. w/ aquaeous Glyoxilic acid and aq. NaOH. Substrates: Phenols, yields are low (~30%)
Patent US4339602
D. w/ aquaeous Glyoxilic acid and Al2O3. Substrate: Catechol, yield:70%.
Patent US4165341
Post 225608 (foxy2: "Re: 4-Methylaminorex Synth w/o CNBr", Novel Discourse)
E. w/ Glyoxilic acid hydrate and 97% Formic acid (in: GAA). Substrate is 1,2,3,5-Tetramethyl benzene, yield: 71%.
Patent DE10029413
F. w/ Glyoxilic acid hydrate and 85% H3PO4. Substrate: 1,2-Methylenedioxybenzene, yield 76%
Patent US4190583
Post 225606 (foxy2: "Re: 4-Methylaminorex Synth w/o CNBr", Novel Discourse)
G. One more method w/ glyoxylic acid: Post 225604 (foxy2: "Re: 4-Methylaminorex Synth w/o CNBr", Novel Discourse)
I’ve found no reference for synthesis of alkoxy substituted mandelic acids. Deffinitely 2,5-Dimethoxymandelic a. would be the most interresting. Yields for both methylendioxybenzene and phenols are high (w/ aq. glyoxylic a., since thats the cheaper solution) thus succes on methoxy substituted compounds may be expected.
For synth of Glyoxilic acids see refs in: Post 427038 (foxy2: "Preparation of Glyoxylic acid", Novel Discourse)
II.) An alternative would be dichlorination of the corresponding acetophenones (lacrymatory), followed by alkaline hydrolysis.
As in:Organic Syntheses, CV 3, 538 (http://www.orgsyn.org/orgsyn/prep.asp?p
(Dibromination may be an alternative.)
III.) Substituted mandelic acids can also prepared from subst. Benzenes by reactingh w/ ethyl oxomalonate in the presence of SnCl4, followed by alkaline hydrolysis.
Organic Syntheses, CV 3, 326 (http://www.orgsyn.org/orgsyn/prep.asp?p
(not too convenient
)Looking forvard for your cooments and suggestions, especially concerning the pemoline analoge possibility and the methoxy issue!
" Unorthodox cooking, illicit cooking. A bit of real science, in fact. "
(Hive Bee)
12-31-03 11:16
No 479961
Condensation of (substituted)Benzaldehyde and Nitromethan --> 1-Phenyl-2-nitroethanol
Patent US2151517
Transformation of Primary Nitroalkanes
1-phenyl-2-nitroethanol --> Mandelic acid
Matt, C.; Wagner, A.; Mioskowski, C.
J. Org. Chem. 62, 234-235 (1997) (../rhodium/pdf /nitro2bromide
DOI:10.1021/jo962110n
.