3 Methyl 4 hydroxy benzaldehyde

The sediment concentrations of anthropogenic compounds in the cove were somewhat less variable than upstream this probably reflects the greater bottom uniformity of the cove. Fewer of the plant s compounds were detected in sediment from the channel where the cove leads into the brackish river (Point 18, Figure 1). Found at this location were various phenols (no. 28, 30a, 30b, 31, 33, 38, 39), di-t-butyl-benzoqui-none (no. 57), 3,5-di-t-butyl-4-hydroxy-benzaldehyde (no. 35), three benzotriazoles (no. 6, 10, 12), 4,4 -dichloro-3(trifluoromethyl) carbanilide (no. 77), and 2-chloro-4,6-bis-isopropylamino-s-triazine (no. 14). The only compounds from the plant detected in the sediment sample from the brackish river (Point 19) were the two high molecular weight benzotriazoles (no. 10 and 12) and methyl 3-(3 ,5 -di-t-butyl-4 -hydroxphenyl) propionate (no. 46). 

Adedeji et al. (1993) used a direct thermal desorption technique (220°C) to analyse the volatiles from beans that might cause the thermal degradation and transformation of sugar into common volatile compounds such as 3,5-dimethyl-2,4(3H,5H)-furandione and 3,5-dihydroxy-6-methyl-2,3-dihydro-4H-pyran-4-one. This last compound was detected at a high concentration (3880 ppm) in Mexican vanilla, being the third most abundant compound after vanillin and 2-furfural, and far more abundant than vanillic acid, p-hydroxy-benzaldehyde or p-hydroxybenzoic acid. 

C6H120 3-methyl-2-pentanone 565-61-7 3.828 10409 C7H602 p-hydroxy benzaldehyde 123-08-0 4.040... 

It is the methyl ether of para-hydroxy benzaldehyde, CeHK... 

According to one Indian manufacturer 3,5-dimethoxy p-cresol is initially oxidized to 3,5-dimethoxy-4-hydroxy-benzaldehyde (syringe aldehyde) which is then methylated to 3,4,5-TMBA... 

A methyl substituted aromatic compound such as p-cresol can be best converted to the corresponding aldehyde such as p-hydroxy benzaldehyde by reacting a methanolic alkaline p-cresol in presence of a mixed co-acetate-Mn-acetate catalyst at a pressure of 8-lOkg/cm and temperature of 75-100°C in presence of air and a solvent such as piperidine or an amine (ammonia, triethylamine, etc.) that would yield approximately 80-90% of the aldehyde in about 16-18 hr. 

In place of SnCl2, HCI even iron powder and an organic acid like formic acid can be used. Meto-hydroxy benzaldehyde is then methylated with dimethyl sulfate in an alkaline medium to produce m-anisic aldehyde... 

Another important industrial process for manufacture of o-anisic aldehyde is based on methylation of o-hydroxy benzaldehyde or salicylaldehyde based on phenol. 

It is reliably learnt that one Japanese company is using Co-acetate-Mn-acetate in a predetermined ratio for oxidation of PCME to p-anisic aldehyde. Similarly these mixed acetate catalysts have been used for oxidation of p-cresol to 7 -hydroxy benzaldehyde at a high pressure (say 10 kg/cm ) and also 3,4,5-trimethoxy benzaldehyde manufacture for conversion of the methyl group to aldehyde as discussed in Chapter 5. Use of this catalyst system is an established fact for oxidation of p-xylene to ptuified terephthalic acid (PTA) or dimethyl terephthalate. 

Similarly, raspberry ketone has so far been made from phenol (and methyl vinyl ketone). However, in view of easy availability of p-hydroxy benzaldehyde from p-cresol at a reasonable price, raspberry ketone can now be made by condensation of alkali catalysed p-hydroxy benzaldehyde and acetone followed by mild hydrogenation of the double bond. 

Analog wird ausgehcnd von 4-Methyl-phenol 4-Hydroxy-benzaldehyd (92% fiir die letzte Stufe Schmp. 116°) erhalten63. 

If the methylation is not complete, some jw-hydroxy-benzaldehyde will remain dissolved in the aqueous phase. This may be recovered by acidifying the alkaline solution and collecting any crystalline solid which separates. 

Keywords Hydrazine hydrate, ethyl acetoacetate, 2-hydroxy benzaldehydes, malononitrile, water, room temperature, one-pot multicomponent synthesis, 2-amino-4-(5-hydroxy-3-methyl-l//-pyrazol-4-yl)-4//-chromene-3-carbonitrile derivatives... 

To a stirred aqueous mixture of hydrazine hydrate 98% (1 0.107 g, 2 mmol) and ethyl acetoacetate (2 0.260 g, 2 mmol), 2-hydroxy benzaldehyde (3 2 mmol), malononitrile (4 0.132 g, 2 mmol) were added successively at ambient temperature (30 °C) tmder an open atmosphere with vigorous stirring for 5-10 min. On completion of the reaction (as monitored by TLC), a sohd precipitate was obtained. The precipitate was filtered, washed with water and then with 5 mL of ethyl acetate/hexane mixture (1 1) affording pure 2-amino-4-(5-hydroxy-3-methyl-l//-pyrazol-4-yl)-4//-chromene-3-carbonitrile (5), characterized by IR, NMR, C-NMR and mass spectral studies. 

Vanilla contains vanillin (1.3-3.0%) as the major flavor component, with over 150 other aroma chemicals also present, most of which are present in traces, including p-hydroxy-benzaldehyde, acetic acid, isobutyric acid, caproic acid, eugenol, furfural, p-hydroxy-benzyl methyl ether, vanillyl ethyl ether, anisyl ethyl ether, and acetaldehyde. The vanillin content differs in different varieties of vanilla, with Bourbon beans containing generally higher amounts than Mexican and Tahiti beans (martindale rosengarten stake). 

Oxidation of / -cresol to -hydroxybenzyl alcohol, />-hydroxy-benzaldehyde, p-hydroxybenzoic acid, and protocatechuic acid by Pseudomonas sp. (Eq, 16) (Dagley and Patel, 1957). o- or wi-Hydroxy or methyl substitution did not alter the oxidation specificity. 

Six protective groups for alcohols, which may be removed successively and selectively, have been listed by E.J. Corey (1972B). A hypothetical hexahydroxy compound with hydroxy groups 1 to 6 protected as (1) acetate, (2) 2,2,2-trichloroethyl carbonate, (3) benzyl ether, (4) dimethyl-t-butylsilyl ether, (5) 2-tetrahydropyranyl ether, and (6) methyl ether may be unmasked in that order by the reagents (1) KjCO, or NH, in CHjOH, (2) Zn in CHjOH or AcOH, (3) over Pd, (4) F", (5) wet acetic acid, and (6) BBrj. The groups may also be exposed to the same reagents in the order A 5, 2, 1, 3, 6. The (4-methoxyphenyl)methyl group (=MPM = p-methoxybenzyl, PMB) can be oxidized to a benzaldehyde derivative and thereby be removed at room temperature under neutral conditions (Y- Oikawa, 1982 R. Johansson, 1984 T. Fukuyama, 1985). 

Alkaline hydrolysis of the crude adduct formed with benzaldehyde, followed by treatment with diazomethane and column chromatography, affords methyl (2R,3S)-3-hydroxy-2-methyl-3-phenylpropanoate in 96% ee. Reduction of the crude products formed in the reactions with 2-inethylpropanal and 2,2-dimethylpropanal leads to the corresponding 1,3-diols with >96% ee. In both the hydrolysis and the reduction procedures, the chiral auxiliary reagent, 1,1,2-triphenyl-1,2-ethanediol, can be recovered and reused72. 

The aldol addition of deprotonated (3-isopropyl-6-methyl-2-oxo-2-propionyl)-l,3.2-oxazaphos-phorinane 36 to benzaldehyde delivers (2f ,3/ )-3-hydroxy-2-methyl-3-phenylpropanoic acid in 47% ee via the /1-lactone 37, with syn/anti ratio of 94 6106c. 

Durst and coworkers were the first to report the condensation of chiral a-sulphinyl carbanions with carbonyl compounds477. They found that metallation of ( + )-(S)-benzyl methyl sulphoxide 397 followed by quenching with acetone gives a mixture of dia-stereoisomeric /i-hydroxy sulphoxides 398 in a 15 1 ratio (equation 233). The synthesis of optically active oxiranes was based on this reaction (equation 234). In this context, it is interesting to point out that condensation of benzyl phenyl sulphoxide with benzaldehyde gave a mixture of four / -sulphinyl alcohols (40% overall yield), the ratio of which after immediate work-up was 41 19 8 32478. 

Benzaldehyd + l-Brom-buten-(2) 4-Hydroxy-3-methyl-4-phenyl-buten-( I) ... 

No stereoselectivity was observed in the formation of a 1 1 diastereomeric mixture of 2-hydroxy-2-phenylethyl p-tolyl sulfoxide 145 from treatment of (R)-methyl p-tolyl sulfoxide 144 with lithium diethylamide . However, a considerable stereoselectivity was observed in the reaction of this carbanion with unsymmetrical, especially aromatic, ketones The carbanion derived from (R)-144 was found to add to N-benzylideneaniline stereoselectivity, affording only one diastereomer, i.e. (Rs,SJ-( + )-iV-phenyl-2-amino-2-phenyl p-tolyl sulfoxide, which upon treatment with Raney Ni afforded the corresponding optically pure amine . The reaction of the lithio-derivative of (-t-)-(S)-p-tolyl p-tolylthiomethyl sulfoxide 146 with benzaldehyde gave a mixture of 3 out of 4 possible isomers, i.e. (IS, 2S, 3R)-, (IS, 2R, 3R)- and (IS, 2S, 3S)-147 in a ratio of 55 30 15. Methylation of the diastereomeric mixture, reduction of the sulfinyl group and further hydrolysis gave (—)-(R)-2-methoxy-2-phenylacetaldehyde 148 in 70% e.e. This addition is considered to proceed through a six-membered cyclic transition state, formed by chelation with lithium, as shown below . ... 

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