Methyl alcohol refractive index

Ethyl Benzoate.—This ester has not been found, so far, to occur naturally in essential oils. It has, however, been prepared by synthetic processes, for example, by condensing ethyl alcohol with benzoic acid by means of dry hydrochloric acid gas. Its odour is very similar to that of methyl benzoate (q.v.), but not quite so strong. It is an oil of specific gravity I OfilO, refractive index 1 5055, and boiling-point 213° at 745 mm. It is soluble in two volumes of 70 per cent, alcohol. 

Detectability may be a significant problem with homologous series of unsaturated compounds, particularly //-alkanes. For these compounds, refractive index detection or evaporative light-scattering, both of which are described elsewhere in the book, may be of use. Indirect photometry is a useful detection scheme for compounds that do not absorb in the UV. Acetone, methylethyl ketone, methyl propyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, and acetophenone are added to an acetonitrile/water mobile phase, generating a negative vacancy peak when the nonchro-mophoric analyte emerges and a positive peak if the ketone is adsorbed and displaced.70 Dodecyl, tetradecyl, cetyl, and stearyl alcohols also have been derivatized with 2-(4-carboxyphenyl)-5,6-dimethylbenzimidazole and the derivatives separated on Zorbax ODS in a mobile phase of methanol and 2-propanol.71... 

Riggio, R., et al., Viscosities, Densities, and Refractive Indexes of Mixtures of Methyl Isobutyl Ketone-Isobutyl Alcohol. J. Chem. Eng. Data, 1984 29, 11-13. 

Methyl Alcohol occurs as a clear, colorless, flammable liquid. It is miscible with water, with ethyl alcohol, and with ether. Its refractive index at 20° is about 1.329. 

As pointed out by Skrabal and Schiffrer [173], the rate-determining step must be in the transition from acetal to hemiacetal because the rate coefficient for the hydrolysis of methyl ethyl formal is equal to the mean value of those for the hydrolyses of dimethyl formal and diethyl formal. Wolf and Hero Id [174] supplied more direct evidence on this matter. They found that the UV absorption bands of aldehydes slowly decrease in alcoholic solutions. This indicates that a reaction takes place. The product of the reaction immediately splits off aldehyde under the conditions of a bisulfite titration, therefore it cannot be acetal and it must be hemiacetal. Acetals are much more stable, and they are not hydrolyzed in a bisulfite titration. A quantitative kinetic study of the reaction of aldehyde with alcohol was carried out by Lauder (175] with the aid of dilatometric and refractive index measurements. He observed that hemiacetal is formed in a relatively fast reaction which is followed by a slow reaction leading to acetal. 

In this project, distinguishing properties of the 10 organic liquids should be observed (Part A) and unknowns subsequently identified (Part B) according to an SOP which I wrote for this. The properties are (1) water miscibility, (2) density, (3) viscosity, (4) refractive index, and (5) odor. The 10 organic liquids are acetone, methanol, ethanol, isopropyl alcohol, heptane, cyclohexane, toluene, methyl ethyl ketone, butanol, and ethyl acetate. 

The reaction was carried out in a 1 L, three-necked flask fitted with a reflux condenser, thermometer, dropping funnel and mercury sealed stirrer. To the flask was added 100 mL water, 300 mL n-propyl alcohol and 196 g oxygen-free zinc dust prepared from commercial-grade zinc dust. The flask was placed in an ice-bath and 244 g (1 mol) of freshly distilled 2-methyl-2,4-dibromopentane was added dropwise with efficient stirring over a period of about 90 min. The icebath was then removed and the mixture was stirred at room temperature for about 32 h. After about 10 h an immiscible layer of hydrocarbon had formed. At the end of the reaction the hydrocarbon product was separated by distillation. The crude product 9 was collected over a temperature range of 49-51 °C and weighed 78.1 g, a yield of 86%. The refractive index of the crude product was 1.3847. The crude product was... 

Determine the weight of the 4-methyl-3-heptanol collected and calculate the percent )4eld. Determine the boiling point and refractive index (optional) of the alcohol, and compare these with values in the literature. 

Specific gravity at 15° C., 1 180-1 187 optical rotation, Gaultheria oil, up to -1°, Betula oil, inactive ester as methyl salicylate, at least 98 per cent. refractive index at 20° 0., l 535i-l 53G4 soluble in 2-6 volumes of 70 per cent, alcohol. 

For a pure mixture of ethyl and methyl alcohols in aqueous solution, the components may be estimated by determination of the density and refractive index of the solution and consultation of published tables. 

Adams and Nicholls state that if a distillate contains less than about 17 per cent of apparent proof spirit, the specific gravity and index of refraction for the low alcohols and acetone are very nearly a linear function of the quantities of each in solution. If the apparent proof spirit be found, then multiplying by the factor 0 585 for methyl alcohol and by 0 573 for ethyl alcohol, for each 1 per cent proof will give the percentage by volume, not differing by more than 0-1 per cent from the correct value. 

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