2-Methoxybenzaldehyde

Other Names Benzaldehyde, o-methoxy- o-Anisaldehyde 2-Anisaldehyde 2-Melhoxybenzalde-hyde 2-Methoxybenzenecarboxaldehyde 2-Methoxyphenylformaldehyde 6-Melhoxybenzaldehyde NC 064 NSC 58960 Salicylaldehyde methyl ether o-Formylanisole o-Methoxybenzaldehyde CA Index Name Benzaldehyde, 2-methoxy-CAS Registry Number 135-02-4 Merck Index Number Not listed Chemical Structure 

Chemical/Dye Class Fluorescent Molecular Formula C8Hg02 Molecular Weight 136.15 pH Range 3.1. 4 

Physical Form Off-white to light yellow crystals Solubility Slightly soluble in water soluble in ethanol Melting Point 37-39°C Boiling Point 238°C Synthesis Synthetic methodsi-  

Major Applications Battery,hair dyes,9.io bird repellents, 112 cosmetics, antibacterial, 4 antipyretic agenti5 

Safety/Toxicity Aquatic toxicity, 6 algae toxicity 7 References 

nt-Hydroxybenzaldehyde. In a 2-1. three-necked flask, equipped with a mechanical stirrer, a thermometer, and a 250-ml. dropping funnel, 575 ml. of 6 iV sulfuric acid is cooled to 0° by means of a salt-ice bath. The aci is stirred and maintained at 0° or below while 167 g. (1 mole) of w-aminobcnzaldehyde dimcthylacetal (j). 6) is added dropwisc. I lie solution becomes 

Caution The methylation should be carried out in a good hood. Methyl sulfate is quite toxic. - 

m-Methoxybenzaldehyde. The crude wi-hydroxybenzalde-hyde is dissolved in about 550 ml. of 2 A7 sodium hydroxide in a 2-1. three-necked flask equipped with a mechanical stirrer, a thermometer, and a 125-ml. dropping funnel. The dark-colored solution is stirred while 126 g. (95 ml., 1 mole) of methyl sulfate (Note 3) is added dropwise and the temperature is maintained at 40-45°. When the addition is complete the mixture is stirred for 5 minutes. A 275-ml. portion of 2 N sodium hydroxide (Note 4) is added in one lot, and then 63 g. (47.5 ml.) of methyl sulfate is added as before, except that the temperature is allowed to rise to 50°. Stirring at 50° is continued for 30 minutes, the mixture is cooled, and the organic layer is extracted w ith ether (Note 5). The ether solution is dried over anhydrous sodium sulfate for 8 hours, then filtered and concentrated by distillation. The residue is distilled under reduced pressure. The yield of w -methoxybenzaldehyde, a pale yellow liquid boiling at 88 90°/3 mm., is 86 98 g. (03 72 %,) (Note 6). 

If w-hydroxybenzaldehyde is desired, the crude product may be purified as described previously.  

A good technical grade of methyl sulfate was used. 

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Diethvlaminoethyl chloride Sodium ethoxide 2-Aminothiophenol 4-Methoxybenzaldehyde... 

Dip Hi% solution Dissolve 1 ml 4-methoxybenzaldehyde (anisaldehyde) and 2 ml cone, sulfuric add in 100 ml gladal acetic add. 

Substances 4-Methoxybenzaldehyde Sulfuric add Acetic add Methanol Ethanol... 

Mercaptoethanol reagent 380 Mercury cations 144,311 Mercury lamps 20, 22 ff emission lines 23, 24 -, high pressure 22 ff -, technical data 23 Mercury(I) nitrate reagent 337 Mercury(II) salt reagent 340 Mesaconic acid 61 Mesoporphyrin 101, 102 Metal cations 310—312,398 Metal complexes 248, 398 Methanol, dipole moment 97 Methine dyestuffs 360 4-Methoxyaniline see Anisidine 4-Methoxybenzaldehyde see Anisaldehyde Methoxybenzaldehyde derivatives 72 Methoxycinnamic acid 277... 

Aliphatic or aromatic aldehydes RCHO can be transformed, in situ, via their iminium iodides, on reaction with enamines of ketones, to give /9-aminoketones. Thus, 4-methoxybenzaldehyde reacts with dimethylammonium chloride, triethyla-... 

Oiganic synthesis 79 [OS 79] Methyl diethoxyphosphonoacetate and 4-methoxybenzaldehyde (Wittig-Horner-Emmons)... 

Methoxybenzaldehyde and methyl diethoxyphosphonoacetate were reacted via the Wittig-Horner-Emmons route to give the corresponding alkene product [85] (see a more detailed description in [42]). 

OS 79] ]R 17] ]no protocol] 4-Methoxybenzaldehyde and methyl diethoxyphos-phonoacetate were reacted by means of the Wittig-Horner-Emmons reaction [85] (see a more detailed description in [42]). A modified micro reaction system consisting of two mixers, for deprotonation of the phosphonates and introduction of the aldehyde, connected to an HPLC capillary of 0.8 m length and 0.25 mm diameter was employed. The micro reactor showed higher yields than laboratory batch synthesis. 

The electrosynthesis of 4-methoxybenzaldehyde (anisaldehyde) from 4-methoxy-toluene by means of direct anodic oxidation is performed on an industrial scale [69]. Via an intermediate methyl ether derivative, the corresponding diacetal is obtained, which can be hydrolyzed to the target product. The different types of products - ether, diacetal, aldehyde - correspond to three distinct single oxidation steps. 

Figure 4.93 Comparison of selectivity and yield for the synthesis of 4-methoxybenzaldehyde depending on reaction temperature and amount of conducting salt [69].

When preparing 4-methoxybenzaldehyde by the action of oxygen on 4-methylanisol, a dramatic output of oxygen caused the reaction to accelerate. 

The synthesis in Scheme 13.5 also makes use of an aromatic starting material and follows a retrosynthetic plan similar to that in Scheme 13.3. The starting material was 4-methoxybenzaldehyde. This synthesis was somewhat more convergent in that the entire side chain except for C(14) was introduced as a single unit by a mixed aldol condensation in step A. The C(14) methyl was introduced by a copper-catalyzed conjugate addition in Step B. 

These efforts began with directed lithiation [53] of commercially available 4-methoxybenzaldehyde dimethyl acetal (117, Scheme 1.12), followed by quenching with amide 118 to produce chloro acetophenone 119 (52 %). Conversion... 

The synthesis of 3-H-oxazol-2-ones was described by Nam et al. [69]. The substituted benzoin 89 was formed from the coupling of 3,4,5-trimethoxy-benzaldehyde 18 with 3-nitro-4-methoxybenzaldehyde, Scheme 22. Reaction with PMB-isocyanate and subsequent cyclization gave the protected oxazolone derivative 90. The PMB group was removed by reflux in TFA and reduction of the nitro-group was performed using Zn to give the combretoxazolone-aniline 91. 

The reaction of thiocarboxamidocinnamonitrile derivative 389 with 2-hydrazinothiazoM(5//)-one in absolute ethanol containing a catalytic amount of triethylamine affords 5-oxopyrano[2,3-z/]thiazolc 390. It has been found that the reaction of compound 390 with chloroacetic acid gives the 5-oxopyrano[ 2,3-z/]thiazole 391. The structure of this compound has been confirmed by its reaction with 4-methoxybenzaldehyde in acetic acid to give the 6-oxopyr-ano[2, 3 4,5]thiazolo[2,3-c][l,2,4]triazole derivative 84 (Scheme 44) <1999ZN(B)1589>. 

Qualitative spot tests for aldehydes, in the presence of ketones, are generally only reliable for water-soluble compounds. This problem can be overcome by the use of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (Purpald , Aldrich Chemical Company) in the presence of Aliquat (Scheme 5.27). Under aerial oxidation, the initially formed colourless cyclic adduct changes colour through red to purple. The colourless cyclic aminal can also be formed by ketones, but only the adducts derived from the aldehydes are oxidized to the purple bicyclic aromatic system [28]. Weakly electrophilic aldehydes, e.g., 4-methoxybenzaldehyde, reacts slowly, but will give the positive coloration upon gentle heating to ca. 70°C for one or two minutes. 

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