P-Methoxy benzaldehyde

A frequently reported spectrophotometric technique for the determination of hydralazine is based on reactions with aromatic aldehydes to form hydrazones with absorption in the visible region. Luk yanchikova et al (5 +) used p-nitrobenzaldehyde Wesley-Hadzija and Abaffy (55) and Ruggieri (56) used p-dimethylaminobenzaldehyde Luk yanchi-kova (57,58) used cinnamaldehyde Schulert (33) used p-hydroxybenzaldehyde and Zak et al (59) used p-methoxy-benzaldehyde, after testing cinnamaldehyde, salicylaldehyde, 3, +,5-trimethoxybenzaldehyde, and 1-naphthaldehyde. 

Problem 19.6 Which would you expect to be more reactive toward nucleophilic additions,p-methoxy-benzaldehyde or p-nitrobenzaldehyde Explain. 

The products obtained were -methoxybenzoic acid and p-methoxy-benzaldehyde, respectively. An analogous reaction sequence starting from 0,0-diethylliensinine (LXV) led to p-ethoxybenzoic acid and p-ethoxybenzaldehyde (38). 

Preparation by reaction between (o-toly-loxy)magnesinm bromide complexed with HMPT and p-methoxy-benzaldehyde in refluxing benzene for 48 h (47%) [50],... 

Problem 19,6 p-Nitrobenzaldehyde is more reactive toward nucleophilic additions than />methoxy-benzaldehyde. Explain. 

Miscellaneous Identified Inhibitors. 3-Acetyl-6-methoxy-benzaldehyde is present in the leaves of the desert shrub Encelia farinosa. It is apparently leached from the leaves and washed into the soil by rain. Concentrations of approximately 0.5 mg. per gram of dried leaf material have been measured. In sand culture studies, growth of tomato seedlings was inhibited by 50 p.p.m. while 115 p.p.m. reduced growth by 50% (53). A concentration of 250 p.p.m. killed the test plants within one day. The structure was confirmed by synthesis, and the synthetic material was shown to be as active as the natural product (54). Derivatives were also prepared in which a cyano, nitro, or amino group was substituted for the aldehyde moiety. The amino derivative was reported to be the most highly toxic. 

The effects of benzaldehyde concentrations on turnover frequency are anomalous. Our results indicate that benzaldehyde hydrogenation turnover frequency is independent of benzaldehyde concentration (an apparent zero-order dependence). However, the data in Table 2 indicate otherwise. If the reaction were independent of aldehyde concentration, the rate data should be independent of the type of aldehyde used. This is especially true with p-tolualdehyde and p-anisaldehyde where the structural changes to the aldehyde (addition of p-methyl or p-methoxy) should influence the reactivity of the aldehyde functionality only through electronic effects. Thus, we are forced to conclude that the aldehyde is involved in the rate determining step even though the concentration study does not support its presence. 

Acetals and ketals having a second junctional group ate made by these procedures. For example, acrolein reacts with ethyl orthoformate in alcohol solution with ammonium nitrate as catalyst to give acrolein diethyl acetal (73%). On the other hand, it reacts with ethyl ortho silicate with anhydrous hydrogen chloride as catalyst to furnish (i-ethoxypropionaldehyde diethyl acetal (76%). p-Bromoacetophenone and ethyl orthoformate give the corresponding ketal in 65% yield. p-Methoxy- and m-amino-benzaldehyde diethyl acetals are made in a similar way in 96% and 85% yields, respectively. a-Keto esters like ethyl a-keto-n-butytate and ethyl a-keto-tr-valetate are converted to their diethyl ketals in excellent yields by the action of orthoformic ester in ethanol-hydrochloric acid solution. If the reaction is carried out in the presence of ethylene glycol instead of ethanol and, in addition, the volatile products are removed by distillation, then the ethylene ketal is formed in almost quantitative yield (cf. method 133). 

Next only to BHT, p-anisic aldehyde, also known as p-anisaldehyde, 4-methoxy benzaldehyde, or Aubepine is the second largest volume organic chemical made from p-cresol. Currently a few important world producers are manufacturing this product having multiple end uses. The major manufacturers are BASF (Germany), Nippon Shokubai (Japan), Atul (India). Koffolk Chemicals (Israel) and Laporte (USA) used to be the two important players but because of a number of reasons they have since then stopped production of p-anisic aldehyde. A few Indian companies apart from Atul have also started manufacture of this material. 

The kinetics of oxidation of substituted mandelic acids (a-hydroxyphenylacetic acid) in sulfate and mixed perchlorate/sulfate solutions are the subject of the four reports from Calvaruso et al. (1981a, b) and Arcoleo et al. (1977,1979). The oxidation reaction yields (substituted) benzaldehydes upon decarboxylation of mandelic acid. The oxidation of the p-nitro and p-methoxy derivatives in sulfuric acid proceeds without significant complex formation. The authors conclude that the reaction proceeds through two reactive Ce(IV) species,... 

Generally a high excess of ketone was used in all these processes. This was not an economical or practical problem when simple and volatile ketones were used as nucleophiles, but could be a severe drawback when more sophisticated ketones were used. The use of ionic liquid such as l-ethyl-3-methyl-l//-imidazolium trifluo-romethanesulfonate ([emim][OTf]) [25] has allowed to reduce the amount of ketones used. Thus, the reaction of a-hydroxyacetone (8a R = H), as well as a-methoxy-acetone (8c R =Me) with p-(trifluoromethyl)benzaldehyde derivatives gave a mixture of three possible isomers of type 9 and 10 with mediocre diastereoselectivities (no enantioselectivities were reported). Under this reaction conditions, a-chloro-(11a) and a-fluoroacetone (lib) were used as source of nucleophile (Scheme 4.4),... 

V-AIkyl Derivatives. — Quatemization of an amino-sugar derivative has been covered in section 2.2. The azi-derivative 62, required as a photoaffinity label, was synthesized from 2-amino-2-deoxy-D-glucose by reductive amination with the propriate aldehyde, as was the pyrimidine derivative 63, the bactericidal activity of which was studied. Addition of dialkyl phosphite to the Schiff base adduct of 4-methyl- or 4-methoxy-benzaldehyde with tetra-0-acetyl-2-amino-2-deoxy-P-D-glucose gave isomeric adducts, e.g. 64. The proportion of the / -isomer formed increased with the size of the alkyl group. ... 

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