Aldehydes tests

The hydrochloride of (3) holds water rather tenaciously, and the infrared spectrum indicates that the water is covalently bound. Mild oxidation of the cation (3) gives 4-hydroxyquinazoline in high yield and ring-chain tautomerism is excluded on the grounds that quinazo-line does not give a positive aldehyde test in acid solution, 2-Methyl-quinazoline also has an anomalous cationic spectrum and a high basic strength (see Table I), but 2,4-dimethylquinazoline is normal in both these respects, which supports the view that abnormal cation formation entails attack on an unsubstituted 4-position. ... 

The reaction is based on an early observation by Angeli and Ahrens that Piloty s acid converted aldehydes to hydroxamic acids, and this has formed the basis of the Angeli-Rimini aldehyde test. Di Maio and Tardella propose the above reaction sequence, consistent with the observed second-order kinetics. The possibility that benzenesulfon-hydroxamic acid would decompose in alkali to give nitroxyl (HNO)... 

The spectra of 1,3,5-, 1,3,7-, and 1,3,8-triazanaphthalerie cations revealed that they were predominantly hydrated, and mild oxidation to the corresponding 4-oxo compounds indicated that hydroxylation took place on C-4. Ring-chain tautomerism in the cation was excluded, at least during the first 45 min after mixing, because negative aldehyde tests were obtained with p-nitrophenylhydrazine. 1,3,6-Triazanaphthalene, under the same conditions, gave a yellow precipit-... 

Tollen s aldehyde test analychem A test that uses an ammonlacal solution of silver oxides to test for aldehydes and ketones. tal anz al da.hTd. test) tolnaftate org chem C19H17NOS An agricultural fungicide It Is also used medically as an antifungal agent. tol naf.tat ... 

Application Detection of aldehydes Test time 25 min Reagent preparation time minutes Recommended storage time N/A (see Notes)... 

In 2000, Kagan and Holmes reported that the mono-lithium salt 10 of (R)- or (S)-BINOL catalyzes the addition of TMS-CN to aldehydes (Scheme 6.8) [52]. The mechanism of this reaction is believed to involve addition of the BI NO Late anion to TMS-CN to yield an activated hypervalent silicon intermediate. With aromatic aldehydes the corresponding cyanohydrin-TMS ethers were obtained with up to 59% ee at a loading of only 1 mol% of the remarkably simple and readily available catalyst. Among the aliphatic aldehydes tested cyclohexane carbaldehyde gave the best ee (30%). In a subsequent publication the same authors reported that the salen mono-lithium salt 11 catalyzes the same transformation with even higher enantioselectivity (up to 97% Scheme 6.8) [53], The only disadvantage of this remarkably simple and efficient system for asymmetric hydrocyanation of aromatic aldehydes seems to be the very pronounced (and hardly predictable) dependence of enantioselectivity on substitution pattern. Furthermore, aliphatic aldehydes seem not to be favorable substrates. 

Ehrlich s aldehyde test can be used to confirm a diagnosis of acute intermittent porphyria. Equal volumes of urine and Ehrlich s reagent are mixed a pink colour indicates raised urinary concentration of either porphobilinogen or urobilinogen. In acute intermittent porphyria, raised porphobilinogen is present and the pink precipitate formed is insoluble in chloroform. 

Water-in-oil gel emulsions were tested in enzymatic aldolization of selected N-Cbz-amino aldehydes (Figure 19.3), N-Cbz-3-amino propanal (4), N-Cbz-glycinal, (5), (S)-N-Cbz-alaninal (6), and (R)-N-Cbz-alaninal (7) catalyzed by RAMA and L-rham-nulose-1-phosphate aldolase (RhuA) and L-fuculose-1-phosphate aldolase (FucA) from Escherichia coU [27,28]. The largest differences between conventional dimethyl formamide (DMF)/water co-solvent systems and gel emulsions were observed with RAMA and FucA catalysts (Figure 19.3). The emulsion media enhanced the catalytic efficiency of RAMA towards the N-Cbz amino aldehydes tested three, five. 

Alcohol isopropylicus, 691 Alcohol trichlorisobutylicus, 444 Alcohols, 18 gas chromatography, 19 test on blood, 6 test on urine, 4 Alcojel, 691 Alcomicin, 637 Alcopar(a), 391 Alcuronium chloride, 324 Aldactide, 667, 973 Aldactone, 973 Aldecin, 374 Aldehyde, 311 Aldehydes, test on blood, 6 test on urine, 4 Alderstan, 324 Aldicarb, 82 Aldoclor, 454, 764 Aldocorten, 324... 

Petrus, D.R., Dougherty, M.H. and Wolford, R.W. 1970. A quantitative total aldehydes test useful in evaluating and blending essences and concentrated citrus products. J. Agric. Food Chem. 18 908-910. 

About 1 g of the dyestuff parafuchsine hydrochloride is dissolved in IL of hot water in the large beaker. After the solution has cooled, sodium hydrogensul-fite is added until the solution is colorless. The aldehyde test is carried out in 4 test tubes 2 mL of the fuchsinesulfurous acid (to which a few crystals of NaHS03 have been added) are added dropwise to 2 mL of each of the samples (sec above) in aqueous-alcoholic solution. After a few minutes the contents of test tubes 1, 2 and 4 are reddish violet in color, while those of test tube 3 remain colorless. 

A thixotropic starch was produced in reactions of POCl3-crosslinked starch with unsaturated aliphatic aldehydes.1361 Starch phosphates have been crosslinked by various aliphatic and aromatic aldehydes in the presence of urea, melamine, and similar compounds. Among several aldehydes tested[formaldehyde, propanal (propionaldehyde), glyoxal, glutaraldehyde, 2-hydroxyadipaldehyde (2-hydroxy -1,6-hexanedial), and some aromatic aldehydes], only those products that had reacted with glyoxal were insoluble in water.1322 Significant increases in viscosity occurred after starch phosphates having a low DS were treated with urea.1590... 

Three indoleacetaldehyde reductases were purified from cucumber seedlings [ 1,4]. The enzyme requiring NADH as a cofactor occurred in the cytosol one of the two NADPH-specific reductases was associated with a microsomal fraction. The latter reduced phenylacetaldehyde at about half the rate observed for indoleacetaldehyde and exhibited minor activity on some of the aliphatic aldehydes tested. The NADH-requiring enzyme acted only on indoleacetaldehyde and phenylacetaldehyde. None of the three enzymes would catalyze the reverse oxidation of tryptophol. 

For all the aldehydes tested, warming up the reaction mixture resulted in the appearance of new peaks, belonging to the corresponding 1,2-addition product, simultaneously with the disappearance of the cuprate signals. When aromatic ketones and 1,3-diketones or keto-esters were tested, formation of the corresponding ir-complexes was detected, albeit with on average lower conversion and stability with respect to the aldehydes. The only exceptions were acetophenone and benzophenone, for which no ir-complex was detected. Fluorenone 99, in contrast, formed a remarkably stable complex 99a (Scheme 36) that was also characterised for the first time by X-ray diffraction [136]. 

They observed that MgAl-LDHs with Fe +, Cu +, and Ni partial incorporation are more active and that benzaldehyde is most effective for the oxidation among the various aldehydes tested. 

Malus communis (ap>ple) Screening for HNL activity in Rosaceae [25], protein isolated, two isoenzymes Only aromatic aldehydes tested 75 (R) — [49]... 

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