4-Anisaldehyde

Anisaldehyde is a colorless oily liquid with an agreeable odor resembling that of coumarin, which is developed only after dilution and in mixtures. 

It is made by the oxidation of anethole (the chief constituent of anise, star anise, and fennel oils). 

Anethole is obtained from the higher-boiling fractions of pine oil. 

4-Dimethylamino-2 -methoxybenzhydrol. An ethereal solution of o-methoxyphenylmagnesium bromide is prepared in the usual manner2 with 250 ml. of anhydrous ether, 14.5 g. (0.60 g. atom) of magnesium, and 100 g. (0.53 mole) of o-bromoanisole (Note 1). A solution of 60 g. (0.40 mole) of / -dimethylamino-benzaldehyde (Note 2) in 200 ml. of anhydrous benzene is added dropwise to the Grignard reagent (Note 3). After the addition is completed, the reaction mixture is stirred for 10 hours at room 

o-Bromoanisole obtained from Eastman Kodak Company was used without further purification. 

In one run the checkers cooled the reaction mixture in an ice bath throughout the addition. In another run only initial cooling was used. There was no difference in yield. 

The checkers found that separation of the aqueous and organic phases is very difficult if the mixture is shaken. In one run shaking and washing were omitted without affecting the yield or purity of the product. 

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Difunctional target molecules are generally easily disconnected in a re/ro-Michael type transform. As an example we have chosen a simple symmetrical molecule, namely 4-(4-methoxyphenyl)-2,6-heptanedione. Only p-anisaldehyde and two acetone equivalents are needed as starting materials. The antithesis scheme given helow is self-explanatory. The aldol condensation product must be synthesized first and then be reacted under controlled conditions with a second enolate (e.g. a silyl enolate plus TiCl4 or a lithium enolate), enamine (M. Pfau, 1979), or best with acetoacetic ester anion as acetone equivalents. 

Most of the thiazoles studied absorb in the ultraviolet above 254 nm, and the best detection for these compounds is an ultraviolet lamp (with plates containing a fluorescent indicator). Other indicator systems also exist, among which 5% phosphomolybdic acid in ethanol, diazotized sulfanilic acid or Pauly s reagent (Dragendorff s reagent for arylthiazoles), sulfuric anisaldehyde, and vanillin sulfuric acid followed by Dragendorff s reagent develop alkylthiazoles. Iodine vapor is also a useful wide-spectrum indicator. 

Reactions of the Hydroxyl Group. The hydroxyl proton of hydroxybenzaldehydes is acidic and reacts with alkahes to form salts. The lithium, sodium, potassium, and copper salts of sahcylaldehyde exist as chelates. The cobalt salt is the most simple oxygen-carrying synthetic chelate compound (33). The stabiUty constants of numerous sahcylaldehyde—metal ion coordination compounds have been measured (34). Both sahcylaldehyde and 4-hydroxybenzaldehyde are readily converted to the corresponding anisaldehyde by reaction with a methyl hahde, methyl sulfate (35—37), or methyl carbonate (38). The reaction shown produces -anisaldehyde [123-11-5] in 93.3% yield. Other ethers can also be made by the use of the appropriate reagent. 

Both -hydroxybenzaldehyde and its methyl ether, -methoxybenzaldehyde [123-11-5] (p-anisaldehyde) have found extensive use in electroplating. The most widespread appHcation has been in alkaline bright zinc plating, both in non-cyanide (77) and in cyanide-containing (78) baths. The aldehydes act as both brightening and leveling agents. 

Hydroxybenzaldehyde has an agreeable aromatic odor, but is not itself a fragrance. It is, however, a useful intermediate in the synthesis of fragrances. The methyl ether of -hydroxybenzaldehyde, ie, -anisaldehyde, is a commercially important fragrance. Anisaldehyde can be made in a simple one-step synthesis from hydroxybenzaldehyde and methyl chloride. Another important fragrance, 4-(p-hydroxyphenyl)butanone, commonly referred to as raspberry ketone, can be prepared from the reaction of -hydroxybenzaldehyde and acetone, followed by reduction (see Flavors and spices). 

Because of the electron-attracting properties of the ring nitrogen atoms, methyl groups undergo aldol-like condensations. For example, 3- and 4-methylpyridazine react with chloral to give 3- or 4-(2-hydroxy-3,3,3-trichloropropyl)pyridazine, and 4-methylpyridazine reacts with anisaldehyde to yield 4-(p-methoxystyryl)pyridazine. 

Cyanohydrin trimethylsilyl ethers are generally useful as precursors of ctir-bonyl anion equivalents and as protected forms of aldehydes. Direct conversion of p-anisaldehyde into 0-TRIMETHYLSILYL-4-METH0XYMANDEL0-NITRILE employs a convenient in situ generation of trimethylsilyl cyanide from chlorotnmethylsilane A general synthesis of allemc esters is a variant of the Wittig reaction. Ethyl (triphenylphosphoranylidene)acetate converts pro-pionyl chloride into ETHYL 2,3-PENTADlENOATE. 

Anisaldehyde carbohydrates 0.5 mL anisaldehyde in 0.5 mL cone H2SO4 + 95% EtOH + a few drops of AcOH Heat at 100-110°C for 20-30 minutes various blue spots... 

The use of an acidic solution of p-anisaldehyde in ethanol to detect aldehyde functionalities on polystyrene polymer supports has been reported (beads are treated with a freshly made solution of p-anisaldehyde (2.55 mL), ethanol (88 mL), sulfuric acid (9 mL), acetic acid (1 mL) and heated at 110°C for 4 min). The colour of the beads depends on the percentage of CHO content such that at 0% of CHO groups, the beads are colourless, -50% CHO content, the beads appear red and at 98% CHO the beads appear burgundy [Vdzquez and Albericio Tetrahedron Lett 42 6691 200]]. A different approach utilises 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (Purpald) as the visualizing agent for CHO groups. Resins containing aldehyde functionalities turn dark brown to purple after a 5 min reaction followed by a 10 minute air oxidation [Coumoyer et al. J Comb Chem 4 120 2002]. 

This method is an adaptation of that of Dengel. -Methoxy-phenylacetonitrile can also be prepared by the metathetical reaction of anisyl chloride with alkali cyanides in a variety of aqueous solvent mixtures by the nitration of phenylaceto-nitrile, followed by reduction, diazotization, hydrolysis, and methylation 1 by the reduction of ct-benzoxy- -methoxy-phenylacetonitrile (prepared from anisaldehyde, sodium cyanide, and benzoyl chloride) and by the reaction of acetic anhydride with the oxime of -methoxyphenylpyruvic acid. ... 

Electrochemical techniques, proposed for the synthesis of naphthaquinone, anisaldehyde, and benzaldehyde (Walsh and Mills, 1993). 

Dissolve 1 ml 4-methoxyben2aldehyde (anisaldehyde) and 2 ml cone, sulfuric acid in 100 ml glacial acetic acid. 

Carefully add 8 ml cone, sulfuric acid and 0.5 ml anisaldehyde under cooling with ice to a mixture of 85 ml methanol and 10 ml glacial acetic acid [1, 4, 8, 11,16]. 

The mechanism of reaction with steroids has not been elucidated. Various nonquantitative reactions occur simultaneously. Cyclopentenyl cations have been postulated as intermediates which condense with anisaldehyde to yield colored compounds [4]. It is probable that triphenylmethane dyes are also formed with aromatic compounds. 

Colour Reactions. Rochelmeyer (1939) has provided a list of colour reactions given by solasodine and solasodiene (solanosodine), with reagents usually applied to the sterols, and Briggs et al. have found that when concentrated sulphuric acid (1 mil) is carefully added to a solution of solasonine or solasodine in hot alcohol (1 mil) a characteristic, intense, greenish-yellow fluorescence is produced, a reaction which is not given by solanine or solanidine. They have also found that intense colours are formed when solasonine or solasodine is mixed with resorcinol, or one of a variety of aldehydes, and boiled with concentrated hydrochloric acid. Colours are also produced with this test by cholesterol, digitonin, jacobine carbazole, pyrrole, or nicotine, the most intense colours being formed with p-hydroxybenzaldehyde or anisaldehyde. 

The same reaction occtns with other aromatic aldehvdes (anisaldehyde, cuminol, furfurol, c ). 

Antispasmodic activity, interestingly, is maintained even in the face of the deletion of the ethanolamine ester side chain. Reaction of anisaldehyde with potassium cyanide and dibutylamine hydrochloride affords the corresponding a-aminonitrile (72) (a functionality analogous to a cyanohydrin). Treatment with sulfuric acid hydrolyzes the nitrile to the amide to yield ambucet-amide (73). ... 

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