Aromatic alcohols are derivatives of benzene homologs, in the radical of which the hydrogen atom is replaced by a hydroxy group. Today, in the perfume industry, benzyl alcohol is very often used. The formula of the indicated compound is represented by the alcohol residue and the benzene (phenyl) radical — 652. Aromatic alcohols are characterized by the isomerism of the side chain radical and the distribution of the - OH group in the hydrocarbon chain. Alcohols in most cases give trivial names.
Benzyl alcohol: methods for producing
Aromatic free alcohols are widespread in nature. As a rule, they are detected in essential oils. Benzyl alcohol is synthesized from halogenated homologues of benzene in which the halogen is localized in the side chain. These alcohols differ from phenols primarily in that they do not have pronounced acidic properties. Benzyl alcohol is also obtained from natural raw materials that contain esters. After that, the aromatic alcohols thus obtained are extracted. Aromatic alcohols are very close to aliphatic alcohols: they form alkoxides under the action of alkali metals; during oxidation, depending on the structure, they turn into the corresponding aldehydes or ketones; very simple form ethers and esters.
Physical properties of alcohols
The first representatives of the homologous series of acyclic alcohols are liquids, and higher alcohols are solids. The first homologues (methanol, ethanol, propanol) have a smell of alcohol, the middle ones (isopropanol, butanol, isobutanol, pentanol, hexanol) have fusel oils, the higher ones have no smell. Alcohols have a high boiling point, which is associated with the association of their molecules with the help of hydrogen bonds. Most of these and other physicochemical properties of alcohols change with an increase in their molecular weight.
It should be borne in mind that during the transition of alcohols from liquid to gaseous state (during boiling), the hydrogen bond is destroyed . In the ultraviolet spectrum there is an absorption band in the region of 150-200 nm. X-ray and electron diffraction made it possible to determine the angle of nonlinear coupling -- equal to 110 ° 25 '. As for aromatic alcohols, they have the same properties as acyclic alcohols. These compounds are poorly or completely insoluble in water, good in organic solvents. The boiling point is much higher than in the corresponding arenas. The absorption band in the UV and IR spectra is similar to aliphatic alcohols.
Chemical properties of aromatic alcohols
These compounds have the same chemical properties as aliphatic alcohols. They form alcoholates, esters and esters, halogenated along the side chain, and upon oxidation, ketones, aldehydes, as well as aromatic acids. In addition, these alcohols may exhibit arene properties. For example, they can enter into the reactions of the benzene core - halogenation, nitration, sulfonation, hydrogenation, etc.
Benzyl alcohol is a solid, readily soluble in ethanol, poorly in water, melts at 15.3 ° C, boils at 205.8 ° C. Get it alkaline hydrolysis of benzyl chloride, the interaction of benzaldehyde with formaldehyde in the presence of sodium hydroxide, from many essential oils and natural balms. Used as an aromatic substance, odor fixative, solvent in the perfume industry.
Beta-phenylethyl alcohol is a solid substance, melts at 27 ° C and boils at 222 ° C, dissolves in ethanol. Included in pink, clove essential oils. Used as an aromatic substance that smells of roses. Also, this substance is often used in the perfumery and food industries.
Cinnamon alcohol is a solid substance, melts at 33 ° C, is readily soluble in ethanol. It is contained mainly in the form of esters in essential oils, odorous resins, balms. An aromatic substance with the smell of hyacinth is used in the perfume industry, as well as as a raw material for the synthesis of most odorous substances.