Benzaldehyde natural

C. Insoluble in water, soluble in organic solvents. Flavone occurs naturally as dust on the flowers and leaves of primulas. It has been prepared from o-hydroxyacetophenone and benzaldehyde. 

A few cyanohydrins and ethers of cyanohydrins occur naturally One species of millipede stores benzaldehyde cyanohydrin along with an enzyme that catalyzes its cleavage to benzaldehyde and hydrogen cyanide m separate compartments above its legs When attacked the insect ejects a mixture of the cyanohydrin and the enzyme repelling the invader by spraying it with hydrogen cyanide... 

Natural" benzaldehyde can be produced in a number of ways. The FDA regulations regarding natural products are found in 21 CFR 101.22. At the present time there is a controversy over what the term natural really means with regard to benzaldehyde. Whether a particular benzaldehyde product is natural or not becomes an issue only if the final product is said to contain natural flavors. 

There are at least two routes currently being used to produce natural benzaldehyde. Principal flavor houses are reported to market a product which is derived from cassia oil. The chief constituent of cassia oil is cinnamic aldehyde which is hydrolyzed into its benzaldehyde and acetaldehyde constituents. This is a fermentative retroaldol reaction. Whether this hydrolysis allows the final benzaldehyde product to be considered natural is of great concern. The FDA has reportedly issued an opinion letter that benzaldehyde produced from cassia oil is not natural (15). 

The other significant production method for natural benzaldehyde involves the steam distillation of bitter almond oil which has been derived from the kernels of fmit such as apricots, peaches, cherries, plums, or pmnes. The benzaldehyde product obtained in this fashion is claimed to have a superior flavor profile. The use of peach and apricot pits to produce the more profitable product laettile apparently affects the supply available to natural benzaldehyde producers. 

The subject of natural benzaldehyde came to the forefront in 1984 when it was found that a natural benzaldehyde product, labeled "oil of benzaldehyde," was actually made synthetically by the air oxidation of toluene followed by careful fractionation to remove trace impurities. This finding was accomphshed by the Center for AppHed Isotopic Studies, University of Georgia, and involved measuring the amounts of and in that material. 

Acetalation. As polyhydroxy compounds, carbohydrates react with aldehydes and ketones to form cycHc acetals (1,13). Examples are the reaction of D-glucose with acetone and a protic or Lewis acid catalyst to form l,2 5,6-di-0-isoprop5lidene-a-D-glucofuranose [582-52-5] and its reaction with benzaldehyde to form 4,6-0-benzyhdene-D-glucopyranose [25152-90-3]. The 4,6-0-(l-carboxyethyhdine) group (related to pymvic acid) occurs naturally in some polysaccharides. 

Not all reactions can be fitted by the Hammett equations or the multiparameter variants. There can be several reasons for this. The most common is that the mechanism of the reaction depends on the nature of the substituent. In a multistep reaction, for example, one step may be rate-determining in the case of electron-withdrawing substituents, but a different step may become rate-limiting when the substituent is electron-releasing. The rate of semicarbazone formation of benzaldehydes, for example, shows a nonlinear Hammett... 

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 ... 

Adolph Baeyer is credited with the first recognition of the general nature of the reaction between phenols and aldehydes in 1872 ([2,5-7] [18], Table 5.1). He reported formation of colorless resins when acidic solutions of pyrogallic acid or resorcinol were mixed with oil of bitter almonds, which consists primarily benzaldehyde. Baeyer also saw resin formation with acidic and basic solutions of phenol and acetaldehyde or chloral. Michael and Comey furthered Baeyer s work with additional studies on the behavior of benzaldehyde and phenols [2,19]. They studied a variety of acidic and basic catalysts and noted that reaction vigor followed the acid or base strength of the catalyst. Michael et al. also reported rapid oxidation and darkening of phenolic resins when catalyzed by alkaline materials. 

In the case of natural bitter almond oil the method gave, uo useful results, presumably because the saponification of Ihn benzaldehyde-evanobydrin into mandilic acid was ineompleic... 

Cinnamic aldehyde, C HgO, is the principal odorous constituent of dnnamon and cassia oils, and is manufactured to a considerable extent, artificially. It can be extracted from the oils in which it occurs by means of sodium bisulphite, the sodium bisulphite compound being decomposed with dilute sulphuric acid, and distilled in a current of steam. The preparation of artificial cinnamic aldehyde, which is used in perfumery as a substitute for the natural oils, is usually carried out. by a condensation of benzaldehyde and acetaldehyde, according to the following reaction —... 

Dodge has based a process for the determination of benzaldehyde. A strong (2 5 N) alcoholic potash solution is required for the estimation, which is performed. by allowing a mixture of 10 c.c. of this solution with 1 to 2 grams benzaldehyde to stand at the ordinary temperature for twenty-four hours, after which the unabsorbed pota is titrated back with N/2 hydrochloric acid. A blank test is also made, and from the amount of potash entering into reaction, the percentage of aldehyde can be calculated. The process breaks down in the assay of natural oil of bitter almonds, probably due to the presence of benzaldehyde cyanhydrin. 

The enol ether double bond contained within the ds-fused dioxa-bicyclo[3.2.0]heptene photoadducts can also be oxidized, in a completely diastereoselective fashion, with mCPBA. Treatment of intermediate XXII, derived in one step from a Patemo-Buchi reaction between 3,4-dimethylfuran and benzaldehyde, with mCPBA results in the formation of intermediate XXIII. Once again, consecutive photocycloaddition and oxidation reactions furnish a highly oxygenated system that possesses five contiguous stereocenters, one of which is quaternary. Intermediate XXIII is particularly interesting because its constitution and its relative stereochemical relationships bear close homology to a portion of a natural product known as asteltoxin. 

The optical purities were determined solely from the optical rotations of the (/ -cyanohydrins thus obtained. Only for (/ )-a-hydroxybcnzeneacetonitrile, available from benzaldehyde, was an optical purity determined by comparison with the natural product. Variation of the reaction conditions (pH, temperature, concentration) in water/ethanol led to no appreciable improvementsl4. The use of organic solvents that are not miscible with water, but in which the enzyme-catalyzed reaction can still take place, resulted in suppression of the spontaneous addition to a significant extent, whereas the enzyme-catalyzed formation of cyanohydrins was only slightly slower (Figure l)13. 

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. 

Aldehydes occur naturally in essential oils and contribute to the flavors of fruits and the odors of plants. Benzaldehyde, C6H5CHO (8), contributes to the characteristic aroma of cherries and almonds. Cinnamaldehvde (9) is found in cinnamon, and vanilla extract contains vanillin (10), which is present in oil of vanilla. Ketones can also be fragrant. For example, carvone (Section 18.1) is the essential oil of spearmint. 

What this implies is that given one equilibrium constant for addition of a nucleophile of known 7 to a carbonyl compound, one could estimate the equilibrium constant for addition of another nucleophile to the same carbonyl compound. This requires knowing the slope of the plot of log K versus y this slope is not very sensitive to the nature of the carbonyl compound, but it is at least known that A H2o/ MeOH depends on the electron-withdrawing power of the groups bonded to the carbonyl, and thus more information is needed to estimate an equilibrium constant for strongly electron-withdrawing substituents. From Ritchie s studies of nucleophile addition to trifluoroacetophenone," we can derive a slope for log K versus 7 of 0.42, distinctly less than the value of 1 for formaldehyde or simple benzaldehydes. 

Formation of the methyl-rhodium complex is analogous to the formation of CH3-C(C0)4 from CH30H2 arid Co(C0K as proposed by Wender. The difference here is that the nature of the active rhodium species is not known. Under the present conditions,homologation does not occur because CO is not present however, addition of the methyl-rhodium species to benzaldehyde must occur as shown in (19), metal adds to the oxygen. The product in (19) is then subject to acid catalyzed etherification to obtain the methyl ether. 

These are materials that are synthetic but are the same compound as is present in a natural flavouring material. From time to time it emerges that one substance produces a given flavour. Most chemists know that benzaldehyde has a smell of almonds. Some chemists know that hydrogen cyanide smells of bitter almonds. If a natural flavouring can be represented by a single substance and that substance can be synthesised then the flavour is likely to be available as a nature identical flavour. Vanilla flavour is a good example. Vanilla flavour can be all natural and derived from vanilla pods or nature identical or artificial. The nature identical product would be based on vanillin, which is in vanilla pods and has a flavour of vanilla. An artificial vanilla flavour would be ethyl vanillin, which is not present in vanilla pods but has a flavour two and a... 

For the synthesis of u-aryl-ZV-methylnitrones a silica gel-NaOH catalytic system has been used. The reaction proceeds without solvents and in good yields, irrespective of the electron-donor or electron-acceptor nature of the substituents in benzaldehyde. Under similar reaction conditions ketones do not undergo the reaction therefore, it makes it possible to carry out selective syntheses in cases where the system contains both aldehyde and ketone groups (154). 

The regiochemistry for trapping lithiooxazole depends upon the oxazole substituents as well as the nature of the electrophile. Hodges, Patt and Connolly observed that the major product of reaction between lithiated oxazole (5 + 6) and benzaldehyde was the C(4)-substituted oxazole 7, resulting from reaction of the dominant acyclic valence bond tautomer 5 via the initial aldol adduct 6 followed by proton transfer and recyclization [3]. 

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