Introduction:
Alcohols are the compounds in which hydrogen of an alkane has been substituted by an -OH group. They encompass -OH group (that is, a hydroxyl) bonded to a saturated alkane such as carbon atom R-OH where 'R' is any simple alkyl or substituted alkyl group. For illustration:
CH3OH CH3CH2OH
Methanol Ethanol
Classes of Alcohols:
Alcohols can have one or more hydroxyl group. It could be:
1) Monohydric: It contain only one hydroxyl group. For illustration: ethanol.
CH3-CH2-CH2-OH
Ethanol
2) Dihydric: It contains two hydroxyl groups. For illustration: ethane-1, 2-diol.
3) Trihydric: It contains three hydroxyl groups. For illustration: propane-1, 2, 3-triol.
Usually with more than one hydroxyl group, it is stated to be polyhydric.
Monohydric alcohols encompass the general formula CnH2n + 1OH. They can be categorized into three classes: primary (1o), secondary (2o) and tertiary alcohol (3o) according to the number of alkyl groups joined to the hydroxyl-bonded carbon atom.
a) Primary alcohol (1°):
It consists of one alkyl group attached to the hydroxyl bonded carbon atom.
Fig: Primary alcohol
For example: CH3OH CH3CH2OH
b) Secondary alcohol (2o):
There are mainly two alkyl groups joined to the hydroxyl-bonded carbon atom.
Fig: Secondary alcohol
c) Tertiary (3o):
There are mainly three alkyl groups; however no hydrogen atom directly attached to the hydroxyl-bonded carbon atom.
Fig: Tertiary alcohol
Naming Alcohols:
a) Common names:
Simple alcohols are often known by their common names that comprises of the name of the alkyl group to which the -OH group is attached followed by the term 'alcohol'.
For illustration:
Methyl alcohol Ethyl alcohol
b) IUPAC names:
In the IUPAC system, alcohols are termed as alkanols and their names are derived from the parent alkane via replacing the 'e' from the parent hydrocarbon and adding the suffix 'ol'.
CH3CH2OH CH3CH2CH2OH
Ethanol Propanol
c) Glycols:
Dialcohols or diols are known as glycols. They are named as the derivatives of parent hydrocarbon by the -diol name ending added. The -OH groups are added as the prefixes.
HOCH2CH2OH
1, 2-Ethanediol
Physical Properties of Alcohols:
1) Physical Appearance:
Most of the simple alcohols are liquid at room temperature. Alcohols having more than twelve carbon atoms are waxy solid at room temperature.
2) Melting and boiling point:
Similar to the parent hydrocarbon, the boiling points among the alcohols increase gradually by the increase in the number of carbon atoms. The boiling point of alcohols is extremely high as compared with that of the corresponding alkane as their capability to form hydrogen bond between the hydrogen atom of the hydroxyl group and the oxygen atom of the other molecule.
The influence of the -OH group though becomes less significant as the carbon skeleton rises.
The order of boiling points of the isomeric alcohols is as follows:
1° alcohol > 2° alcohols > 3° alcohols
3) Density:
The density of alcohols increases by increasing the relative molecular mass, though, branching can decrease this effect.
All the simple alcohols are less dense than water; however the aromatic homologues are slightly denser than water.
4) Solubility:
Hydrogen bonding in alcohols affects their solubility in water. Alcohols by a relatively short carbon skeleton are soluble in water. For illustration: methane, ethanol, propan-1-o1 and propan-2-o1 are fully miscible with water in all chains increases, the solubility of alcohols drop drastically.
All the alcohols are miscible by most organic solvents like hexane, benzene and ethanol; the smaller ones are helpful organic solvents.
Tutorsglobe: A way to secure high grade in your curriculum (Online Tutoring)
Expand your confidence, grow study skills and improve your grades.
Since 2009, Tutorsglobe has proactively helped millions of students to get better grades in school, college or university and score well in competitive tests with live, one-on-one online tutoring.
Using an advanced developed tutoring system providing little or no wait time, the students are connected on-demand with a tutor at www.tutorsglobe.com. Students work one-on-one, in real-time with a tutor, communicating and studying using a virtual whiteboard technology. Scientific and mathematical notation, symbols, geometric figures, graphing and freehand drawing can be rendered quickly and easily in the advanced whiteboard.
Free to know our price and packages for online Chemistry tutoring. Chat with us or submit request at [email protected]
Looking for top-rated Microprocessor Assignment Help service at budget-friendly prices? Hire qualified tutors and secure top-notch grades easily.
www.tutorsglobe.com offers chemical analysis homework help, chemical analysis assignment help, online tutoring assistance, inorganic chemistry solutions by online qualified tutor's help.
www.tutorsglobe.com offers Program Quality Quantification homework help, assignment help, case study, writing homework help, online tutoring assistance by computer science tutors.
Isolation-Structure Determination of Natural Products tutorial all along with the key concepts of General Methods of Extraction, Aqueous extraction of compounds, Fractionation, Fractionation by chromatography, Adsorption chromatography
tutorsglobe.com antigens assignment help-homework help by online immunology tutors
Theory and lecture notes of Dynamic Characteristics III, all along with the key concepts of Inverter Fall Time, Storage Time and Rise-Time. Tutorsglobe offers homework help, assignment help and tutor’s assistance on Dynamic Characteristics III.
tutorsglobe.com intermediate inheritance assignment help-homework help by online genetics tutors
Oxides and Oxoacids of Halogens tutorial all along with the key concepts of Preparation of Halogen Oxides, Properties of Halogen Oxides, Structure of Oxides of Halogens, Interhalogen Compounds, Properties of Interhalogen compounds and Structure of Interhalogen Compounds
Theory and lecture notes of Measuring the Macroeconomy all along with the key concepts of Measuring the macroeconomy, Importance of Data, Real GDP, unemployment rate, level of stock market and inflation rate. Tutorsglobe offers homework help, assignment help and tutor’s assistance on Measuring the Macroeconomy.
tutorsglobe.com digestion assignment help-homework help by online biochemistry tutors
Potential for Continuous Charge Distribution and Energy tutorial all along with the key concepts of Potential due to an Infinite Line Charge, Equipotential surface of a Uniformly Line Charge and Electrostatic Potential Energy
Theory and lecture notes of Sources of Divergence all along with the key concepts of sources of divergence, Policies and Long-Run Growth, Savings and Investment, Policies for Technological Advance, Neoliberalism. Tutorsglobe offers homework help, assignment help and tutor’s assistance on Sources of Divergence.
tutorsglobe.com ornithophily assignment help-homework help by online agents of pollination tutors
Theory and lecture notes of Stock Market all along with the key concepts of the stock market, Government Purchases, Domestic Components of Aggregate Demand, homework help, assignment help. Tutorsglobe offers homework help, assignment help and tutor’s assistance on Stock Market.
tutorsglobe.com chemical co-ordination assignment help-homework help by online co-ordination systems tutors
1938726
Questions Asked
3689
Tutors
1453353
Questions Answered
Start Excelling in your courses, Ask an Expert and get answers for your homework and assignments!!