Benzaldehyde conversion

Dtmng the experimental runs it was shown that the above selectivity is dependent on the reduction level of the catalyst. These data agree with the published results of Trimm and Irshad (2). It vras found that the selectivity of toluene to benzaldehyde increases with reaction time, while the toluene conversion shows to be practically constant. These results indicate that a given ratio of V / V, after the process of oxidation must be attained, so that satisfactory values of toluene to benzaldehyde conversion are obtained. 

Figure 7.3 shows good agreement of experimental data and theoretical predictions for benzaldehyde conversion by Rhodotorula Mucilaginosa.8... 

Figure 5. Benzaldehyde oxidation over sample c. benzaldehyde conversion i residue CO 2 space-time 0.4 mgcat. min/ml.

In the presence of even moderate bases, imidazolium cations can be deprotonated to form N-heterocyclic carbenes [45]. These are reactive bases [46], and can act as catalysts [47-51]. These are usually discussed in the context of facing challenges. For exanple, the disparity between the high benzaldehyde conversions (as determined by GC) and low product yields in... 

The conversion and selectivities to toluene and benzene were determined after Ih of reaction, when nearly steady-states were reached. Table 1 shows the influence of chemical composition on catalytic properties of CaTiOs and substituted perovskites on benzaldehyde conversion reaction. Compared to CaTiOs, the substituted perovskites are less active under H2 flow and the benzaldehyde conversion decreases with the increasing of Ca substitution by Mg in the following order ... 

To investigate the high selectivity of PhCHO in the present reaction condition, reaction of PhCHO in an acetonitrile suspension of ft-Ti02 was carried out under the same irradiation condition. Benzaldehyde conversion and H2 yield were much smaller (7.6 % and 2 pmol, respectively, for 1 h) than BnOH conversion and H2 yield (>99 % and 48 pmol, respectively, for 1 h), indicating that the reactivity of PhCHO was much smaller than that of BnOH in this condition. The smaller reactivity was attributed to the high selectivity of PhCHO in the photocatalytic oxidation of BnOH in an acetonitrile suspension of Pt-Ti02. Photocatalytic oxidation of aldehyde under a deaerated condition is generally calculated in Eq. 9.27 ... 

Place 5 ml. of benzaldehyde in a wide-necked stout-walled bottle of about 100 ml. capacity (a conical flask is too fragile for this purpose) and add 50 ml. of concentrated dy 0 880) ammonia solution. Cork the bottle securely, shake vigorously, and then allow to stand for 24 hours, by which time the layer of benzaldehyde at the bottom of the bottle will have been converted into a hard mass of hydrobenzamide. (If after 24 hours the crude hydrobenzamide is still syrupy, shake the mixture vigorously and allow to stand for another hour, when the conversion will be complete.) Break up the solid pellet with a strong spatula, filter at the pump, wash with water and drain thoroughly. Recrystallise from ethanol methylated spirit should not be used, as it contains sufficient water to cause partial hydrolysis back to benzaldehyde and ammonia. Hydrobenzamide is obtained as colourless crystals, m.p. 101° (and not 110° as frequently quoted) yield, 4 g. 

Benzoin condensation. Aromatic aldehydes when treated with an alkali cyanide, usually in aqueous solution, undergo condensation to the -hydroxyketone or benzoin. The best known example is the conversion of benzaldehyde to benzoin ... 

It is important to mix the mandelonitrile with hydrochloric acid immediately it has been separated from the water. Standing results in rapid conversion to the acetal of benzaldehyde and mandelonitrile C(H,CH[OCH(CN)C H,] and/or the iso-nitrile the yield of mandelic acid will, in consequence, be reduced. 

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. 

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. 

Nearly all of the benzyl chloride [100-44-7], henzal chloride [98-87-3], and hen zotrichl oride /P< -(97-i manufactured is converted to other chemical intermediates or products by reactions involving the chlorine substituents of the side chain. Each of the compounds has a single primary use that consumes a large portion of the compound produced. Benzyl chloride is utilized in the manufacture of benzyl butyl phthalate, a vinyl resin plasticizer benzal chloride is hydrolyzed to benzaldehyde hen zotrichl oride is converted to benzoyl chloride. Benzyl chloride is also hydrolyzed to benzyl alcohol, which is used in the photographic industry, in perfumes (as esters), and in peptide synthesis by conversion to benzyl chloroformate [501-53-1] (see Benzyl ALCOHOL AND p-PHENETHYL ALCOHOL CARBONIC AND CARBONOCm ORIDIC ESTERS). 

It is commercially prepared from benzaldehyde and hydrogen cyanide. Mandelonitrile is used by certain insects (tiger beedes, an African millipede) as a defense duid (38). After expelling the duid an enzyme catalyzes the conversion of mandelonitrile to benzaldehyde and HCN, which is usually fatal to the insect s enemy. 

A series of chiral boron catalysts prepared from, e.g., N-sulfonyl a-amino acids has also been developed and used in a variety of cycloaddition reactions [18]. Corey et al. have applied the chiral (S)-tryptophan-derived oxazaborolidine-boron catalyst 11 and used it for the conversion of, e.g., benzaldehyde la to the cycloaddition product 3a by reaction with Danishefsky s diene 2a [18h]. This reaction la affords mainly the Mukaiyama aldol product 10, which, after isolation, was converted to 3a by treatment with TFA (Scheme 4.11). It was observed that no cycloaddition product was produced in the initial step, providing evidence for the two-step process. 

The free acid analogue of the antipsoriatic agent etretinate (103) is prepared in substantially the same way as the parent compound. Thus, the aldehyde group in 98 is converted finally to the pho.sphonate (101) by sequential reduction (99), conversion to the chloride (100), and finally reaction with triethyl phosphite. Condensation of the ylide from 101 with the benzaldehyde 102 gives etretinate (103) saponification affords acitretin (104) [25]. 

N Phenylhydroxylamine condensation, with benzaldehyde to form N,a-diphenylmtronc, 46,127 with n-butyraldehyde, 46, 96 Phenyl lsothiocyanate, 46, 21 Phenylhthium, 46, 109 N-Phenylmaleimide, conversion to 3-phenyl-3 -propylisoxazolidinc-... 

Process economics dictate the recycling of the unwanted isomer. Path A in Figure A8.2 illustrates that racemisation of the D-N-benzylidene amino add amide is fadle and can be carried out under very mild reaction conditions. After removal of die benzaldehyde die D,L-amino add amide can be recyded 100% conversion to the L-amino add is theoretically possible. Another method for racemisation and recycling of the L-amino add (path B, Figure A8.2) comprises the conversion of the L-amino add into die ester in the presence of concentrated add, followed by addition of ammonia, resulting in the formation of the amide. Addition of benzaldehyde and racemisation by OH- (pH =13) gives the D,L-amino add amide. In this way 100% conversion to die D-amino add is possible. 

It is better to add the benzaldehyde and the COgMe group first so that conversion of COgH to CHO does not affect the reactive NH2 or SH group. Note that diborane, BgHg, reduces COgH even in the presence of an ester. 

The results shown in Figure 5 confirm that benzaldehyde concentrations were maintained close to the desired value while pyruvate concentrations increased to approx. 200 mM presumably due to its slower conversion (than predicted) to acetoin and acetaldehyde. After 55 h a maximum PAC concentration of approx. 300 mM was reached, while acetoin and acetaldehyde concentrations were 20 mM and 5 mM, respectively. A residual PDC activity of 35% remained at this time. 

The intrinsic conversion (%.m 2) of malononitrile and benzaldehyde versus time is shown in Figure 2. Commercial MgO (40 m. g-l) used in the same conditions as the "AlPONs" (i.e. without pretreatment) gives a low conversion [14]. Without pretreatment MgO is not an extremely basic compound but these results show that "AlPONs" are more active than MgO at the chosen conditions and such a character could be useful for industrial applications. 

Figure 8.12 Conversion of benzaldehyde into enantiomerically pure (S)-mandelic acid by the sequential addition of HCN catalyzed by the (.S )-selective oxynitrilase from Manihot esculenta (MeHnL), and subsequent hydrolysis of the resultant (5)-mandelonitrile by the nitrilase from Pseudomonas fluorescens ECB 191 (PfNLase)...

Sulfur ylides are a classic reagent for the conversion of carbonyl compounds to epoxides. Chiral camphor-derived sulfur ylides have been used in the enantioselective synthesis of epoxy-amides <06JA2105>. Reaction of sulfonium salt 12 with an aldehyde and base provides the epoxide 13 in generally excellent yields. While the yield of the reaction was quite good across a variety of R groups, the enantioselectivity was variable. For example benzaldehyde provides 13 (R = Ph) in 97% ee while isobutyraldehyde provides 13 (R = i-Pr) with only 10% ee. These epoxy amides could be converted to a number of epoxide-opened... 

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