Aldehyde Sentence Examples
Duclaux found that acetic acid is formed in small quantities during fermentation; aldehyde has also been detected.
According to this theory a " chemical type " embraced compounds containing the same number of equivalents combined in a like manner and exhibiting similar properties; thus acetic and trichloracetic acids, aldehyde and chloral, marsh gas and chloroform are pairs of compounds referable to the same type.
The thermal effect of the aldehyde group has the average value 64.88 calories, i.e.
They are hydrolysed by dilute mineral acids yielding hydroxylamine and the parent aldehyde or ketone.
The aldehyde group reacts with hydrocyanic acid to produce two stereo-isomeric cyanhydrins; this isomerism is due to the conversion of an originally non-asymmetric carbon atom into an asymmetric one.Advertisement
The aldehyde group also reacts with phenyl hydrazine to form two phenylhydrazones; under certain conditions a hydroxyl group adjacent to the aldehyde group is oxidized and glucosazone is produced; this glucosazone is decomposed by hydrochloric acid into phenyl hydrazine and the keto-aldehyde glucosone.
When this compound is acted on by water, hydrogen peroxide and levulinic aldehyde are formed, the aldehyde being subsequently oxidized by the hydrogen peroxide, forming levulinic acid.
These are colourless crystalline compounds, which are most readily prepared by passing ammonia gas into an ethereal solution of the aldehyde.
Both oximes and hydrazones, on boiling with dilute acid, regenerate the parent aldehyde.
The hydrazones are best prepared by mixing the aldehyde with phenylhydrazine in dilute acetic acid solution, in the absence of any free mineral acid.Advertisement
With ammonia, benzaldehyde does not form an aldehyde ammonia, but condenses to hydrobenzamide, (C 6 H 5 CH) 3 N 2, with elimination of water.
Piperonal (q.v.) is the corresponding aldehyde.
He prepared the cyanhydrins of glucose and fructose, hydrolysed them to the corresponding oxy-acids, from which the hydroxy groups were split out by reduction; it was found that glucose yielded normal heptylic acid and fructose methylbutylacetic acid; hence glucose is an aldehyde alcohol, CH 2 OH (CH OH) 4 CHO, whilst fructose is a ketone alcohol CH 2 OH (CH OH) 3 CO.
These reactions permit the transformation of an aldose into a ketose; the reverse change can only be brought about by reducing the ketose to an alcohol, and oxidizing this compound to an aldehyde.
The trioses are the aldehyde and ketone mentioned above as oxidation products of glycerin.Advertisement
Glyceric aldehyde, CH 2 OH CH(OH) CHO, was obtained pure by Wohlon oxidizing acrolein acetal, CH 2 CH(OC 2 H 5) 21 and hydrolysing.
Impure inactive forms result on the polymerization of glycollic aldehyde and also on the oxidation of erythrite, a tetrahydric alcohol found in some lichens.
Employing the notation in which the molecule is represented vertically with the aldehyde group at the bottom, and calling a carbon atom+or - according as the hydrogen atom is to the left or right, the possible configurations are shown in the diagram.
Chemically they appear to be ether anhydrides of the hexoses, the union being effected by the aldehyde or alcohol groups, and in consequence they are related to the ethers of glucose and other hexoses, i.e.
Dumas, who regarded them as hydrates of olefiant gas (ethylene); on the other they yielded chloroform, chloral and aldehyde, as well as other compounds of less general interest, and also the method of forming mirrors by depositing silver from a slightly ammoniacal solution by acet aldehyde.Advertisement
Wallach, Ber., 1881, 14, P. 421); by the action of reducing agents on nitroparaffins; by the action of zinc and hydrochloric acid on aldehyde ammonias (German Patent 73,812); by the reduction of the phenylhydrazones and oximes of aldehydes and ketones with sodium amalgam in the presence of alcohol and sodium acetate (J.
Fittig and his pupils (Annalen, 1883, 216, pp. loo, 115; 1885, 227, pp. 55, 119), in which it was shown that the aldehyde forms an addition compound with the sodium salt of the fatty acid, and that the acetic anhydride plays the part of a dehydrating agent.
It possesses all the characteristic properties of an aldehyde; being readily oxidized to benzoic acid; reducing solutions of silver salts; forming addition products with hydrogen, hydrocyanic acid and sodium bisulphite; and giving an oxime and a hydrazone.
The oxidation of benzaldehyde to benzoic acid when exposed to air is not one of ordinary oxidation, for it has been observed in the case of many compounds that during such oxidation, as much oxygen is rendered " active " as is used up by the substance undergoing oxidation; thus if benzaldehyde is left for some time in contact with air, water and indigosulphonic acid, just as much oxygen is used up in oxidizing the indigo compound as in oxidizing the aldehyde.
This solution is frequently used as a test reagent for the detection of aldehydes, giving, in most cases, a red coloration on the addition of a small quantity of the aldehyde.Advertisement
The first compound, containing a group COH, or more explicitly 0 = CH, is an aldehyde, having a pronounced reducing power, producing silver from the oxide, and is therefore called propylaldehyde; the second compound containing the group - C CO C - behaves differently but just as characteristically, and is a ketone, it is therefore denominated propylketone (also acetone or dimethyl ketone).
It consists essentially of cinnamic aldehyde, and by the absorption of oxygen as it becomes old it darkens in colour and develops resinous compounds.
When mesitylene is used, the reaction does not proceed beyond the aldehyde stage since hydrocarbon formation is prevented by the presence of a methyl group in the ortho-position to the -CHO group. Acids and alkalis are in general without action on nickel carbonyl.
In 1867 Wurtz prepared neurine synthetically by the action of trimethylamine on glycol-chlorhydrin, and in 1872 he discovered aldol, pointing out its double character as at once an alcohol and an aldehyde.
It has been suggested that urea is formed by polymerization of ammonium carbonate, and formic aldehyde is synthesized from CO 2 and 011 2.
He studied the formation of aldehyde from alcohol by various methods, also obtaining its crystalline compound with ammonia, and he was the discoverer of furfurol.
In this reaction the proportions of aldehyde and acetoacetic ester may be interchanged and ay disubstituted pyridines are then obtained.
Alkyl pyridines -CO /COare also obtained by heating aldehyde ?
The reaction is a perfectly general one, for the aniline may be replaced by other aromatic amines and the aldehyde by other aldehydes, and so a large number of quinoline homologues may be prepared in this way.
Riiber (Ber., 1902, 35, p. 2411; 1904, 37, P. 22 74), by oxidizing diphenyl-2.4-cyclo-butane-bismethylene malonic acid (fron cinnamic aldehyde and malonic acid in the presence of quinoline) with potassium permanganate.
Oxidation by strong oxidizing agents converts it successively into its aldehyde, acrolein, and into acrylic acid.
If the Schiff's reagent quickly becomes magenta, then you are producing an aldehyde from a primary alcohol.
If at least one of these groups is a hydrogen atom, then you will get an aldehyde.
Jasminum Absolute produced positive patch test reactions in some patients who were contact sensitive to cinnamic aldehyde.
In the presence of even small amounts of an aldehyde, it turns bright magenta.
The retinol is oxidized to its aldehyde, retinal, which complexes with a molecule in the eye called opsin.
A bright orange or yellow precipitate shows the presence of the carbon-oxygen double bond in an aldehyde or ketone.
Polymerization of the aldehyde was also a feature of Baeyers hypothesis, so that this view does not very materially differ from those he advanced.
Categorized as a floral aldehyde and oriental, the scent was designed with a strong-willed woman in mind.
The men's version is a blend of violet, aldehyde, lime, coriander, green tea, vetiver, white pepper and musk, while the women's version contains frosted citrus, ginger, green tea and peony, among other notes.