Benzaldehyde, substituted

Reaction with dimethylphenylsilane is catalyzed at room temperature under 250 psi of carbon monoxide. Other silanes tested, triethyl- and triphenylsi-lane, are not effective reagents in this system. A variety of aldehydes are good substrates for the reaction, including benzaldehyde, substituted benzaldehydes, and heterocyclic aldehydes. Aliphatic aldehydes also yield a-siloxy aldehyde products, but the reaction must be run at higher CO pressure (1000 psi) to avoid hydrosilylation. The reaction does not tolerate substrates bearing strong electron-withdrawing substituents, such as p-nitrobenzaldehyde. 

Few examples of [4 + 2] cycloadditicMis of aromatic aldehydes with simple alkyl-, halo- and alkoxy-substituted 1,3-dienes exist. Ansell and Charalambides found that benzaldehydes substituted with electron-withdrawing groups such as nitro and cyano undergo thermal cycloaddition.Other benzaldehydes were found to cycloadd only in the presence of p-toluenesulfonic acid. 

Malachite Green is a representative of a whole series of dyes,—the Malachite Green Series. If, instead of dimethyl aniline, diethyl aniline is used, an analogous substance, which bears the name of Brilliant Green, is formed. In place of benzaldehyde, substituted benzalde-hydes, etc., can be used. The dyes of the Bitter Almond Series colour only the animal fibres, silk and wool, directly. Vegetable fibre (cotton) is not coloured unless it has been previously mordanted. 

The acid-catalyzed condensation of pyrrole with benzaldehyde substituted by a carbohydrate residue gave rise to symmetric meso-tetrakis(glycosylaryl)por-phyrins. 

Aldehydes. Formaldehyde, metaformaldehyde, acetaldehyde, paraldehyde, chloral hydrate, benzaldehyde, salicylaldehyde (and other substituted benzaldehydes). 

The higjily water-soluble dienophiles 2.4f and2.4g have been synthesised as outlined in Scheme 2.5. Both compounds were prepared from p-(bromomethyl)benzaldehyde (2.8) which was synthesised by reducing p-(bromomethyl)benzonitrile (2.7) with diisobutyl aluminium hydride following a literature procedure2.4f was obtained in two steps by conversion of 2.8 to the corresponding sodium sulfonate (2.9), followed by an aldol reaction with 2-acetylpyridine. In the preparation of 2.4g the sequence of steps had to be reversed Here, the aldol condensation of 2.8 with 2-acetylpyridine was followed by nucleophilic substitution of the bromide of 2.10 by trimethylamine. Attempts to prepare 2.4f from 2.10 by treatment with sodium sulfite failed, due to decomposition of 2.10 under the conditions required for the substitution by sulfite anion. 

Ni(N03)2 6H20, Cu(N03)2 3H20, Zn(N03)2-4H20 and KNOj were of the highest purity available. Substituted 3-phenyl-l-(2-pyridyl)-2-propene-ones (2.4a-e) were prepared by an aldol condensation of the corresponding substituted benzaldehyde with 2-acetylpyridine, following either of two modified... 

Nitration using this reagent was first investigated, by Francis. He showed that benzene and some of its homologues bromobenzene, benzonitrile, benzoyl chloride, benzaldehyde and some related compounds, and phenol were mono-nitrated in solutions of benzoyl nitrate in carbon tetrachloride anilines would not react cleanly and a series of naphthols yielded dinitro compounds. Further work on the orientation of substitution associated this reagent with higher proportions of o-substitution than that brought about by nitric acid this point is discussed below ( 5.3.4). 

METHOD 1 This section is going to be as thoroughly helpful to those interested in X production as it will be to those interested in amphetamine production. The process is known as the Knoeve-nagel-Walter condensation which can turn a substituted benzal-dehyde such as piperonal (X) or plain old benzaldehyde (speed) into an intermediate called a p-nitropropene. This intermediate can then be transformed into MDA (Benzedrine for speed) or MD-P2P (P2P for speed) depending on the capabilities of the chemist. 

METHOD 2 [89]--1M MDA or benzedrine and 1M benzaldehyde is dissolved in 95% ethanol (Everclear), stirred, the solvent removed by distillation then the oil vacuum distilled to give 95% yellow oil which is a Schiff base intermediate. 1M of this intermediate, plus 1M iodomethane, is sealed in a pipe bomb that s dumped in boiling water for 5 hours giving an orangy-red heavy oil. The oil is taken up in methanol, 1/8 its volume of dH20 is added and the solution refluxed for 30 minutes. Next, an equal volume of water is added and the whole solution boiled openly until no more odor of benzaldehyde is detected (smells like almond extract). The solution is acidified with acetic acid, washed with ether (discard ether), the MDMA or meth freebase liberated with NaOH and extracted with ether to afford a yield of 90% for meth and 65% for MDMA. That s not a bad conversion but what s with having to use benzaldehyde (a List chemical) Strike wonders if another aldehyde can substitute. 

The 5-substituted 2-methyl-A-2-thiazoline-4-one derivative (188) yields a condensation product (189) when treated with p-dimethylamino-benzaldehyde Scheme 98 (434). The condensation occurs on the a-2. carbon. 

When benzaldehyde or its substituted derivatives are added to carbon disulfide and a-aminonitrile, the corresponding 2-mercapto-5-(p-R-benzylideneamino)thiazoles (215), R = hydrogen atom or a propenyl or phenyl group and Ar = aryl, are obtained (Scheme 112) (393, 442, 694). Yields ranged from 40 to 60% (Table II-34b). 

By condensing carbon oxysulfide with o-aminOnitriles the corresponding 2-hydroxy-5-aminothiazoles can be obtained. In the presence of benzaldehyde or its substituted derivatives the reaction leads to 5-benzy-lideneaminothiazole derivatives (218) in good yields (Scheme 114 and Table 11.35) (393, 442). However, the reaction fails with or-amino acetonitrile (206), R = H (317). The 2-alkoxy analogs (220), R = Me, Et, Pr, Bu, vinyl, were similarly obtained from 219 and benzylideneamino acetonitrile (Scheme 115a) (393). 

Reactions were carried out by condensing the o-aminoacetonitrile with carbon oxysulfide in the presence of benzaldehyde or its substituted derivatives, in aicoho) as solvent. 

Substituted 5-hydroxythiazoles (267b), Rj = alkylmercapto, acyl-amino, and sec-amino, are prepared by cydization of N-thioacyl-amino acids (266) with phosphorus tribromide or acetic anhydride (Scheme 137) (317, 350). i en the cydization of 266, R2 = H, is carried out with acetic anhydride in the presence of benzaldehyde (317, 325) or ethylformate (317), the benzylidene (268), R2=Ph, Rj = SR or CH2Ph, or 4-ethoxymethylene (268), Rj = SR and R2 = OEt, derivative is obtained directly (Scheme 138). 

Various substituted benzaldehydes react with 2,4-dimethylthiazole at the 2-methyl group (6, 282). Results have been obtained with... 

Because the carbon atom attached to the ring is positively polarized a carbonyl group behaves m much the same way as a trifluoromethyl group and destabilizes all the cyclo hexadienyl cation intermediates m electrophilic aromatic substitution reactions Attack at any nng position m benzaldehyde is slower than attack m benzene The intermediates for ortho and para substitution are particularly unstable because each has a resonance structure m which there is a positive charge on the carbon that bears the electron withdrawing substituent The intermediate for meta substitution avoids this unfavorable juxtaposition of positive charges is not as unstable and gives rise to most of the product... 

Reactions. Heating an aqueous solution of malonic acid above 70°C results in its decomposition to acetic acid and carbon dioxide. Malonic acid is a useful tool for synthesizing a-unsaturated carboxyUc acids because of its abiUty to undergo decarboxylation and condensation with aldehydes or ketones at the methylene group. Cinnamic acids are formed from the reaction of malonic acid and benzaldehyde derivatives (1). If aUphatic aldehydes are used acryhc acids result (2). Similarly this facile decarboxylation combined with the condensation with an activated double bond yields a-substituted acetic acid derivatives. For example, 4-thiazohdine acetic acids (2) are readily prepared from 2,5-dihydro-l,3-thiazoles (3). A further feature of malonic acid is that it does not form an anhydride when heated with phosphorous pentoxide [1314-56-3] but rather carbon suboxide [504-64-3] [0=C=C=0], a toxic gas that reacts with water to reform malonic acid. 

The apphcation of (5)-oxynitrilase has been reported only recendy (159). The enzyme isolated from shoots of Sorghum catalyzes the condensation between various 3- and 4-substituted benzaldehydes and hydrogen cyanide resulting in (5)-cyanohydrins in 80—90% yield and up to 99% ee. 

Compound (253) is formed from benzaldehyde and methylhydroxylamine-O-sulfonic acid in 35% yield. With ethyl-substituted chloramine or hydroxylamine-O-sulfonic acid yields do not exceed 10%, which is assumed to be due to steric hindrance and is foreseeable for both carbonyl addition and O —N bond formation. 

This procedure has been applied successfully to the synthesis of substituted bistyryls, i.e., l-( -tolyl)-4-phenylbutadiene (76%), l-(4-methoxyphenyl)-4-phenylbutadiene (63%), and l-(4-acetamidophenyl)-4-phcnylbutadiene (61%), by using the corresponding substituted benzaldehydes. 

The rates of substituted benzaldehydes are correlated by the Hammett equation with p = +3.76. 

The rates of both formation and hydrolysis of dimethyl acetals of -substituted benzaldehydes are substituent-dependent. Do you expect to increase or decrease with increasing electron-attracting capacity of the pam substituent Do you expect the Ahydroi to increase or decrease with the electron-attracting power of the substituent How do you expect K, the equilibrium constant for acetal formation, to vary with the nature of the substituent ... 

Raney Nickel W2 or W4, EtOH, 85-100% yield. Mono- and dimethoxy-substituted benzyl ethers and benzaldehyde acetals are not cleaved under these conditions, and trisubstituted alkenes are not reduced. 

Darzens reaction can be used to efficiently complete the stereoselective synthesis of a"-substituted epoxy ketones. As an example, Enders and Hett reported a technique for the asymmetric synthesis of a"-silylated a,P-epoxy ketones. Thus, optically active a -silyl a-bromoketone 38 was treated with LDA followed by the addition of benzaldehyde to give a"-silyl epoxyketone 40 in 66% yield with good... 

In 1909, Patemo and Chieffi noted that mixtures of tri- or tetra-substituted olefins and aldehydes formed trimethylene oxides when exposed to sunlight. Biichi later repeated Patemo s experiments by irradiating 2-methyI-2-butene in the presence of benzaldehyde, butyraldehyde, or aeetophenone and rigorously purifying and identifying the resulting products. The reaction thus bears the name of its two primary pioneers and has come to represent any photo-catalyzed [2 + 2] electrocyclization of a carbonyl and an alkene. 

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