Esters analysis

In esters analysis, most esters are low melting point liquids or solids, many with characteristic floral and fruity odors. Their IR spectra show strong carbonyl bands from 1780 to 1720 cm-1 accompanied by two strong C-O absorptions in the region of 1300 to 1050 cm-1. The main method for the characterization of an ester involves … Read more

Analysis of sulfur compounds (thiols)

In the analysis of sulfur compounds (thiols), due to the different oxidation states of sulfur, there are many compounds that contain sulfur: thiols, sulfides, disulfides, sulfoxides, sulfones, sulfenic, sulfinic and sulfonic acids, etc. Their exhaustive study is beyond the limits of this page. Only as an example we will deal with thiols. They have an … Read more

Analysis of quinones

Quinones are colored crystalline compounds (most of them are yellow) with a pungent odor. They show in the IR spectrum a carbonyl band near 1670 cm-1. Iodide test Most quinones release iodine from acidified potassium iodide solutions. Oximes and semicarbazones Quinones often form oximes and semicarbazones that often do not have the usual structure. Reduction … Read more

Analysis of nitro compounds

In the analysis of nitrocompounds, one of the characteristics of these compounds is that most of them are colorless liquids. They turn yellow when stored. They have characteristic odors, are insoluble in water and are denser than water. Most aromatic nitrocompounds are yellow crystalline solids. In the IR spectrum, they show two strong bands at … Read more

Analysis of ethers

In ether analysis, ethers, like hydrocarbons, are not very reactive but can be distinguished from ethers by the iodinecharge transfer test and by solubility in H2SO4 (not diaryl ethers). When ethers are left to stand exposed to air and light they have a tendency to form highly explosive peroxides. Ferrox paper test Procedure: this paper … Read more

Analysis of carbohydrates

Carbohydrate analysis focuses on mono– and –disaccharides which are colorless solids or viscous liquids that dissolve readily in water. In the IR spectrum they exhibit strong hydroxyl absorptions and usually no carbonyl absorption. A main feature of carbohydrate analysis is that the “reductant” sugars are oxidized by the Tollens’ reagent and the Fehling reagent (see … Read more

Analysis of amides

Almost all amides are colorless crystalline solids. In the analysis of amides, the observation of the infrared (IR) spectrum is important. In this spectrum, two bands are observed in the region of the carbonyl group (amide I and II) in addition to the stress band of the N-H group in the region of 3400 cm-1. … Read more

Analysis of aromatic hydrocarbons

The analysis of aromatic hydrocarbons gives negative results in the tests with bromine in CCl4 and with alkaline permanganate, and they also burn with a characteristic dark flame. Most alkylated aromatic hydrocarbons are liquids, but those with more than one ring (fused or not) are solids. Solubility in H2SO4: Simple aromatic hydrocarbons are insoluble in … Read more

Analysis of alkyl halides

In the analysis of alkyl halides, the presence or absence of halogens in organic compounds can be determined by the Beilstein test, consisting of the formation of copper halides that give the flame a green or blue coloration, or by the analysis of the filtrate obtained after fusion with sodium. In order to classify the … Read more

Analysis of aldehydes and ketones

Common characteristics of aldehydes and ketones Aldehydes and ketones have characteristic reactions in common due to the presence of the carbonyl group in both, but they also have distinct reactions due to the property of aldehydes to be oxidized to acids by the action of mild oxidants. The analysis of aldehydes and ketones focuses on … Read more