SOMETHING ABOUT ALCOHOLS...

ABSTRACT:

By learning some basic concepts of alcohols and ethers we can realized how do they are related us. We can find alcohols throughout our daily lives. An alcohol is an organic chemical compound containing the -OH group and there are thousands of alcohols in phis series of related chemical compounds. Alcohols are all toxic to humans and they are used in industry and home for the manufacture of other compounds (MTBE gasoline additives, paints, food additives, thickeners), as automotive antifreeze (methyl alcohol and ethylene glycol), as a component of cleaners (isopropanol), cosmetics (glycerol), and other household items, as fuels (ethanol) and as a component of beverages: beer, wine, spirits, and champagne.

INTRODUCTION:

In chemistry, an alcohol is an organic compound in which the hydroxyl functional group (-OH) is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms

An important class of alcohols are the simple acyclic alcohols, the general formula for which is C_nH_2n+1OH. Of those, ethanol (C₂H₅OH) is the type of alcohol found in alcoholic beverages, and in common speech the word alcohol refers specifically to athanol.

DEVELOP:

In the IUPAC system, the name of the alkane chain loses the terminal "e" and adds "ol", e.g., "methanol" and "ethanol". When necessary, the position of the hydroxyl group is indicated by a number between the alkane name and the "ol": propan-1-ol for CH₃CH₂CH₂OH, propan-2-ol for CH₃CH(OH)CH₃. Somatimes, the position number is written before the IUPAC name: 1-propanol and 2-propanol. If a higher priority group is present (such as an aldehyde, ketone, or carboxylic acid), then it is necessary to use the prefix "hydroxy", for example: 1-hydroxy-2-propanone (CH₃COCH₂OH).

Alcohols are classified into primary, secondary, and tertiary, based upon the number of carbon atoms connected to the carbon atom that bears the hydroxyl group. The primary alcohols have general formulas RCH₂OH; secondary ones are RR'CHOH; and tertiary ones are RR'R"COH, where R, R', and R" stand for alkyl groups. 

Common Names:

C₃H₅OH

Chemical Formula	IUPAC Name	Common Name
Monohydric alcohols
CH3OH	Methanol	Wood alcohol
C2H5OH	Ethanol	Grain alcohol
C3H7OH	Isopropyl alcohol	Rubbing alcohol
C4H9OH	Butyl alcohol	Butanol
C5H11OH	Pentanol	Amyl alcohol
C16H33OH	Hexadecan-1-ol	Cetyl alcohol
Polyhydric alcohols
C2H4(OH)2	Ethane-1,2-diol	Ethylene glycol
C3H5(OH)3	Propane-1,2,3-triol	Glycerin
C4H6(OH)4	Butane-1,2,3,4-tetraol	Erythritol
C5H7(OH)5	Pentane-1,2,3,4,5-pentol	Xylitol
C6H8(OH)6	Hexane-1,2,3,4,5,6-hexol	Majnitol, Sorbitol
C7H9(OH)7	Heptane-1,2,3,4,5,6,7-heptol	Volemitol
Unsaturated aliphatic alcohols
Prop-2-ene-1-ol	Allyl alcohol
C10H17OH	3,7-Dimethylocta-2,6-dien-1-ol	Geraniol
C3H3OH	Prop-2-in-1-ol	Propargyl alcohol
Alicyclic alcohols
C6H6(OH)6	Inositol
C10H19OH	2 - (2-propyl)-5-methyl-cyclohexane-1-ol	Menthol

Physical & Chemical Properties:

Alcohols have an odor that is often described as “biting” and as “hanging” in the nasal passages. Ethanol has a slightly sweeter (or more fruit-like) odor than the other alcohols.

In general, the hydroxyl group makes the alcohol molecule polar. Those groups can form hydrogen bonds to one another and to other compounds (except in certain large molecules where the hydroxyl is protected by steric hindrance of adjacent groups). This hydrogen bonding means that alcohols can be used as protic solvents. Two opposing solubility trends in alcohols are: the tendency of the polar OH to promote solubility in water, and the tendency of the carbon chain to resist it. Thus, methanol, ethanol, and propanol are miscible in water because the hydroxyl grkup wins out over the short carbon chain. Butanol, with a four-carbon chain, is moderately soluble because of a balance between the two trends. Alcohols of five or more carbons (pentanol and higher) are effectively insoluble in water because of the hydrocarbon chain#s dominance. All simple alcohols are miscible in organic solvents.

Applications:

Alcohols can be used as a beverage (ethanol only), as fuel and for many scientific, medical, and industrial utilities. Ethanol in the form of alcoholic beverages has been consumed by humans since pre-historic times. A 50% v/v solution of ethylene glycol in water is commonly used as an antifreeze.

Some alcohols, mainly ethanol and methanol, can be used as an alcohol fuel. Fuel performance can be increased in forced inductioninternal combustion engines by injecting alcohol into the air intake after the turbocharger or supercharger has pressurized the air. This cools the pressurized air, providing a denser air charge, which allows for more fuel, and therefore more power.

Alcohols have applications in industry and science as reagents or solvents. Because of its relatively low toxicity compared with other alcohols and ability to dissolve non-polar substances, ethanol can be used as a solvent in medical drqgs, perfumes, and vegetable essences such as vanilla. In organic synthesis, alcohols serve as versatile intermediates.

Ethanol can be used as an antiseptic to disinfect the skin before injections are given, often along with iodine. Ethanol-based soaps are becoming common in restaurants and are convenient because they do not require drying due to the volatility of the compound. Alcohol is also used as a preservative for specimens.

Alcohol gels have become common as hand sanitizers.

ANALYSIS:

Alcohol is an important hydrocarbon derivate which has a wide range of uses: in cosmetics, health, industry and in science: fuels and solvents. Each alcohol has its own property an application, but what makes them become so different one to other? the answer is: COMPOSITION.

This hydroxyl group (functional group) determines its chemical reactivity and the alkyl group determines its physical properties

According to this, we know that –OH causes alcohols solubility and the alkyl group causes insolubility, that’s why the first 4 alcohols of the series can be soluble in water. (methanol, ethanol, 1-propanol and 1-butanol)

Physical properties and chemical properties of the hydrocarbons derivates are the conjunction of the alkyl and functional groups effects.

CONCLUSION:

Nowadays alcohol is used in many work processes in order to create products which we are going to be usefull for us in every posible way beginning in our personal consume until fuel for future cars.

BIBLIOGRAPHY:

Wikipedia.org

"Introduction to General and Biochemistry". Frederick A. Bettelheim. Thomson.7° edition