Odor aldehyde

Froese, K. L., A. Wolanski, and S. E. Hruday, Factors governing odorous aldehyde formation as disinfection by-products in drinking water , Wat. Res., 33,1355-1364 (1999). 

Chang, J.C.S. and Guo, Z. (1998) Emissions of odorous aldehydes from alkyd paint. Atmospheric Environment, 32, 3581-6. 

Linoleic acid has two non-conjugated double bonds and consequently the theoretical number of hydroperoxides is higher. The main hydroperoxy-octadienoic acids are 9-HPOD, lO-HPOD, 12-HPOD and 13-HPOD (cf. Fig. 3.29). Further reaction produces among others the odorant aldehydes hexanal (35), 2( )-heptanal (36), 2( )-octenal (37), 2(Z)-octenal (38), 2( )-nonenal (39), 3(Z)-nonenal (40), 2,4( , )-decadienal (41) and 2,4( , Z)-decadienal (42). The potent odorant 41 (odour threshold 0.2 mg/kg... 

In a simple test, such as benzidine, anisidine or heptanal values, the volatile aldehydes are not separated from fat or oil, rather the reaction with the group-specific reagents is carried out in the fat or oil. In addition to the odorous aldehydes, the flavorless oxo-acylglycerols and oxo-acids can be... 

Smell or odor Aldehydes and other volatile organics, many from hemicellulose While not toxic, the smell is often objectionable... 

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. 

Many esters occur naturally Those of low molecular weight are fairly volatile and many have pleasing odors Esters often form a significant fraction of the fragrant oil of fruits and flowers The aroma of oranges for example contains 30 different esters along with 10 carboxylic acids 34 alcohols 34 aldehydes and ketones and 36 hydrocarbons... 

Aldehydes, enals, dienals, ketones, and hydrocarbons, which are responsible for disagreeable odors, generally bok at lower temperatures than fatty acids. Analysis showkig a free fatty acid concentration of less than 0.05% is an kidication that deodorization is sufficientiy complete. Some of the dienals have very low odor thresholds and sensory evaluation of the finished ok is a judicious quaHty assurance step. 

Substances other than enzymes can be immobilized. Examples include the fixing of heparin on polytetrafluoroethylene with the aid of PEI (424), the controUed release of pesticides which are bound to PEI (425), and the inhibition of herbicide suspensions by addition of PEI (426). The uptake of anionic dyes by fabric or paper is improved if the paper is first catonized with PEI (427). In addition, PEI is able to absorb odorizing substances such as fatty acids and aldehydes. Because of its high molecular weight, PEI can be used in cosmetics and body care products, as weU as in industrial elimination of odors, such as the improvement of ambient air quaHty in sewage treatment plants (428). 

Aldehydic Floral Family. This is an important family of fragrances, the typical odor of which is the class odor of the aldehydes. The aldehydes are present in small quantities in nature and have an uimatural brilliance. Although they have sharp, slightly fmity odors alone, they blend beautifully and unexpectedly in florals. 

The Prins reaction with formaldehyde, acetic acid, acetic anhydride, and camphene gives the useful alcohol, 8-acetoxymethyl camphene, which has a patchouli-like odor (83). Oxidation of the alcohol to the corresponding aldehyde also gives a useful iatermediate compound, which is used to synthesize the sandalwood compound dihydo- P-santalol. 

The sulfur dioxide can be recovered and recycled. The myrcenol, after purification by distillation, can condense with acrolein to produce Lyral [31906-04-4], an important aldehyde with a strong-lasting odor similar to Lily-of-the-valley (92). 

Aldol reaction of the campholenic aldehyde with 2-butanone gives the intermediate ketones from condensation at both the methyl group and methylene group of 2-butanone (Fig. 6). Hydrogenation results in only one of the two products formed as having a typical sandalwood odor (160). 

Fig. 6. Campholenic aldehyde (81) reacts with 2-butanone to produce ketones that are hydrogenated to alcohols having the odors indicated.

Aldol reaction of campholenic aldehyde with propionic aldehyde yields the intermediate conjugated aldehyde, which can be selectively reduced to the saturated alcohol with a sandalwood odor. If the double bond in the cyclopentene ring is also reduced, the resulting product does not have a sandalwood odor (161). Reaction of campholenic aldehyde with -butyraldehyde followed by reduction of the aldehyde group gives the aHyUc alcohol known commercially by one manufacturer as Bacdanol [28219-61 -6] (82). 

When the a,P-unsaturated ketone is hydrogenated to the alcohol, a product with an intense sandalwood odor is produced (162). Many other examples of useful products have been made by condensation of campholenic aldehyde with ketones such as cyclopentanone and cyclohexanone. 

Phenyhsonitrile has a powerful characteristic odor it is used as a qualitative test (the carbylamine test) for chloroform or primary aromatic amines. Chloroform reacts with phenols in alkaline solution to give hydroxyaromatic aldehydes in the Reimer-Tiemann reaction eg, phenol gives chiefly Nhydroxyben2aldehyde and some sahcylaldehyde (11) (see Hydroxybenzaldehydes). 

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