Alcohols identification

Caine, D., Halliday, G.M., Kril, J.J., and Harper, C.G. (1997). Operational criteria for the classification of chronic alcoholics identification of Wernicke s encephalopathy. J. Neurol. Neurosurg. Psychiatr. 62 51-60. 

Salicylic acid Sodium molybdate anhydrous Sodium molybdate dIhydrate Sodium phosphate dibasic anhydrous Sulfanilic acid Tannic acid Thallium (I) sulfate reagent, analytical alcohol identification... 

Bergh, M. Shao, L.P. Magnusson, K. Gafvert, E. Nilsson, J.L.G. Karlberg, A. Atmospheric oxidation of polyoxyethylene alcohols. Identification of ethoxylated formates as oxidation products and study of their contact allergenic activity. J. Pharm. Sci. 1999, 88, 483 88. 

Unfortunately, in most cases not all the available information on a reaction is given in the reaction equation in a publication, and even less so in reaction databases. To obtain a fuller picture of the reaction that was performed, the text describing the experimental procedure in the publication or a lab journal) would have to be consulted. Reaction products that are considered as trivial, such as water, alcohol, ammonia, nitrogen, etc., are generally not included in the reaction equation or mentioned in the text describing the experimental work. This poses serious problems for the automatic identification of the reaction center. It is highly desirable to have the full stoichiometry of a reaction specified in the equation. 

The reaction between 3,5 dinitrobenzoyl chloride and compounds containing the OH, NHj, or NH groups is very rapid, and therefore is particularly suitable for identification purposes cf. pp. 335, 338, 381). It is usual to have sodium hydroxide present during the reaction with phenols and amino-acids, but this is not necessary with alcohols if they are dry. 

The above example serves to iUustrate the basis of the procedure employed for the characterisation of aUphatic esters, viz., hydrolysis to, and identification of, the parent acids and alcohols. Most esters are liquids a notable exception is dimethyl oxalate, m.p. 54°. Many have pleasant, often fruit-hke, odours. Many dry esters react with sodium, but less readily than do alcohols hydrogen is evolved particularly on warming, and a sohd sodio derivative may separate on coohng (e.j/., ethyl acetate yields ethyl sodioacetoacetate ethyl adipate gives ethyl sodio cj/cZopentanone carboxylate). 

The following give abnormal results when treated with chlorosulphonio acid alone, preferably at 50° for 30-60 minutes —fluobenzene (4 4 -difluorodiplienyl-sulphone, m.p. 98°) j iodobenzene (4 4 -di-iododiphenylsulplione, m.p. 202°) o-diclilorobenzene (3 4 3. -4 -tetrachlorodiphenylsulphone, m.p. 176°) and o-dibromobenzene (3 4 3 4 -tetrabromodiphenylsulphone, m.p. 176-177°). The resulting sulphones may be crystallised from glacial acetic acid, benzene or alcohol, and are satisfactory for identification of the original aryl halide. In some cases sulphones accompany the sulphonyl chloride they are readily separated from the final sulphonamide by their insolubility in cold 6N sodium hydroxide solution the sulphonamides dissolve readily and are reprecipitated by 6iV hydrochloric acid. 

Polarimetric analysis of sorbitol and mannitol in the presence of each other and of sugars is possible because of their enhanced optical rotation when molybdate complexes are formed and the higher rotation of the mannitol molybdate complex under conditions of low acidity (194). The concentration of a pure solution of sorbitol may be determined by means of the refractometer (195). Mass spectra of trimethylsilyl ethers of sugar alcohols provide unambiguous identification of tetritols, pentitols, and hexitols and permit determination of molecular weight (196). 

TYZOR ET is reduced by sodium and ethanol to a dark-blue compound (182). Use of potassium as the reducing agent in the alcohol permits the isolation and identification of Ti(OC2H2)3 [22922-82-3] and Ti(OC4Hg)3 [5058-41-3] (183,184). The products precipitate as soUd alcoholates,... 

Phenethyl alcohol may be identified as the phenethyl -nitrobenzoate [57455-00-2] (mp 106—108°C), as phenethyl -nitrobenzyl phthalate [65997-34-4] (mp 84.3°C), and also by its formation of styrene on treatment with alkaU. Use of these derivatives has, however, been superseded by physical methods. Infrared (75,76), mass spectroscopy (77), and nmr spectra (78) are useful for identification. 

The earliest references to cinnamic acid, cinnamaldehyde, and cinnamyl alcohol are associated with thek isolation and identification as odor-producing constituents in a variety of botanical extracts. It is now generally accepted that the aromatic amino acid L-phenylalanine [63-91-2] a primary end product of the Shikimic Acid Pathway, is the precursor for the biosynthesis of these phenylpropanoids in higher plants (1,2). 

This reaction can be used for identification of individual alcohols because of the wide variations noted in the melting points of monoalkyl esters up to the dodecyl derivatives. The reaction can be used to separate alcohols of various classes. Monoesters are converted into the normal diesters by heating with an excess of alcohol and a catalyst however, diesters are generally formed directiy from the corresponding diacids. 

At identification of cognacs and cognac alcohols on authenticity use the following characteristic attributes presence in them significant concentration of (15-150 mg/1) bytanol, the high level of acids - acetic, propionic and oil the high contents of polyphenolic bonds. 

Carbocations can also be generated during the electrolysis, and they give rise to alcohols and alkenes. The carbocations are presumably formed by an oxidation of the radical at the electrode before it reacts or diffuses into solution. For example, an investigation of the electrolysis of phenylacetic acid in methanol has led to the identification of benzyl methyl ether (30%), toluene (1%), benzaldehyde dimethylacetal (1%), methyl phenylacetate (6%), and benzyl alcohol (5%), in addition to the coupling product bibenzyl (26%). ... 

Nitroso-pinene may be prepared for identification purposes as follows To a solution of 12 grams of sodium in 30 c.c. of 90 per cent, alcohol, 100 grams of pinene-nitrosochloride are added. The mixture is boiled on a water-bath, under a reflux condenser, until the reaction is complete. Water is added, the-clear solution filtered from insoluble impurities, and the filtrate poured into excess of acetic acid. The nitroso-pinene separates as an oil which solidifies to a yellowish mass in a few days. This is broken up, washed with water, and dried on a porous plate. It can be recrystallised from acetic ether, when it is obtained in the pure condition, and then melts at 132°. 

The identification of camphene is best carried out by its conversion into isobomeol under the influence of acetic acid in the presence of sulphuric acid. In order to effect this conversion, 100 grams of the fraction containing the terpene in substantial quantity are mixed with 250 grains of glacial acetic acid and 10 grams of 50 per cent, sulphuric acid. Tne mixture is heated for two to three hours on a water-bath to a temperature of 50° to 60°. At first the liquid separates into two layers, bat soon becomes homogeneous and takes on a pale red colour. Excess of water is added, and the oil which is precipitated, and which contains the isobomeol in the form of its acetate, is well washed with water repeatedly. It is then saponified by heating with alcoholic potash solution on a water-bath. The liquid is then evaporated and extracted with water, and the residue recrystallised from petroleum ether. 

For the identification of terpinolene, its tetrabromide is the most characteristic compound. This body is prepared by adding gradually four atoms of bromine to a solution of the terpene in glacial acetic acid, maintained at a low temperature. Terpinolene tetrabromide, C], Hj,.Br., melts at 116° to 117°, when recrystallised from alcohol. 

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