Introduction:
Alcohol might be prepared by using the given methods.
Hydrolysis of halogenoalkanes:
This reaction is appropriate for the preparation of primary, secondary and tertiary alcohols. All the halogenoalkane whenever heated under reflux with aqueous potassium hydroxide solution are hydrolyzed to yield an alcohol.
RX + KOH ↔ (reflux) ↔ ROH + X-
Here X = I-, Br-, Cl- and R = alkyl group
The easiness of reaction of the halogenoalkanes follows the order of:
RI > RBr > RCl
Hydration of alkene:
This reaction is just the addition of water molecule to the alkene to form the corresponding alcohol. It comprises the addition of concentrated tetraoxosulphate (VI) acid first to the alkene to provide alkyl hydrogen tetraoxosulphate (VI) which whenever treated with water (hydrolysis), provides an alcohol.
For illustration, the formation of ethanol:
CH2 = CH2 + H2SO4 → CH3-CH2HOSO3 + H2
Conc. Ethyl hydrogen tetraoxosulphate (vi)
CH3-CH2HOSO3 + H2O → CH3CH2OH + H2SO4
Ethanol
Industrially, hydration of ethane is taken out in the vapor phase by employing tetraoxophosphate (V) acid supported on silicon (VI) oxide as the catalyst. The reaction is taken out at high temperature and under pressure.
CH2 = CH2 (g) + H2O (g) → (H3PO4 on SiO2 at 33oC, 60atm) → CH3CH2OH (g)
Reduction of Aldehydes and ketones:
Addition of Organometallic reagents to Aldehydes and ketones:
Organometallic reagents (RLI or RMgX) react by aldehydes and ketones to provide alcohols.
Use of RLi:
Fig: Use of RLi
Reaction with RMgX:
In this reaction, the intermediate alkyl magnesium halide is hydrolyzed by employing the dilute acid or aqueous ammonium chloride in the case of tertiary alcohols.
Fig: Reaction with RMgX
Use of Lithium tetrahydridoaluminate (III), ( LiAlH4)
Primary and secondary alcohols can be made up from the reduction of aldehydes and ketones by utilizing Lithium tetrahydridoaluminate (III), LiAlH4 in dry ether.
For illustration:
Fig: Use of Lithium tetrahydridoaluminate
Lithium tetrahydridoborate (III), LiBH4, in dry ether, a milder reducing agent can as well be employed as the alternative reagent.
Fermentation of carbohydrates:
Industrially, ethanol can be made up from the fermentation of carbohydrates.
The biological catalysts, enzymes, found in the yeast maltase break-down the sugar molecules to the ethanol to give a yield which is in the region of 95 percent.
2(C5H10O5)n + nH2O → (diastase at 60°C) → nC12H22O11
Starch Maltose
C12H22O11 + H2O → (maltase at 15°C) → 2C6H12O6
Maltose Glucose
C6H12O6 → (zymase at 15°C) → 2CH3CH2OH + 2CO2
Glucose is rarely employed in practice as the initial substrate has some other appropriate and cheaper raw materials like potatoes, cereals and rice are available. The percentage of ethanol can be increased through distillation of the reaction product: to give a mixture having 95.5 by mass of ethanol and 4.43% water. The mixture is termed as rectified spirit having a constant boiling point of 78.2°C. Anhydrous calcium chloride can't be utilized to eliminate the residual water as reacts with alcohols to form compounds of the kinds CaCl2. nC2H5OH. On distilling over quicklime, CaO that reacts with only water however not with the alcohol, absolute alcohol (99.5% alcohol) is obtained. The last traces of water can be eliminated from this by refluxing it by metallic calcium and redistilling.
Absolute ethanol is highly hygroscopic and should be stored away from the atmospheric moisture if its purity is to be maintained.
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]
Selected Financial Reporting Standards , IAS 8 Accounting Policies, Changes in Accounting Estimates and Errors, IAS 10 Events after the Reporting Period
linear motion tutorial all along with the key concepts of Motion in a Straight Line and Parameters for describing Motion, Displacement, Velocity, Instantaneous velocity, Average and instantaneous acceleration, Rectilinear motion with constant acceleration, Rectilinear Motion Equations
each task description should identify inputs, their sources. and due dates. outputs or task results should be indentified and described as to where each result goes.
www.tutorsglobe.com offers Control Constructs homework help, assignment help, case study, writing homework help, online tutoring assistance by computer science tutors.
Morphology of algae tutorial all along with the key concepts of Algal Morphology, Unicellular Forms, Colonial Algae, Filamentous Forms, Heterotrichous Forms, Thalloid Forms and Polysiphonoid Forms
theory and lecture notes of regular expressions all along with the key concepts of regular expressions, finite automata and regular languages, warshall and floyd algorithm, closure of the class of regular sets, state minimization. tutorsglobe offers homework help, assignment help and tutor’s assistance on regular expressions.
Ionic equilibria tutorial all along with the key concepts of Electrolytes and Non-Electrolytes, General Concepts of Acids and Bases, Arrhenius Concept, Lowry and Bronsted concept, Lewis Concept, Attributes of acids and bases
While a vacuum cleaner fails to clear the dirt efficiently, we consider of replacing it with another one. Although troubleshooting a vacuum cleaner is not a so hard task.
Now let us converse the range of computers that we see today. Even though they related to the fifth generation they can be split into dissimilar categories relies on the efficiency, size, memory and number of users
Polysaccharides tutorial all along with the key concepts of Types of polysaccharides, Homopolysaccharides, Heteropolysaccharides, Cellulose, Starch, Glycogen, Pectins, Hyaluronic acid and Chondroitin
Proteins and their Structures tutorial all along with the key concepts of Definition and Diversity of Proteins, Protein Structure and Levels of Protein Structure
Theory and lecture notes of Determinant of a Square Matrix all along with the key concepts of Elementary Row Operations, Triangular Matrices, Larger Order Determinants, Inverse of a Matrix, Cofactors, Matrix of Minors, Minors. Tutorsglobe offers homework help, assignment help and tutor’s assistance on Determinant of a Square Matrix.
tutorsglobe.com principle of acceleration assignment help-homework help by online determinant of income and employment tutors
concepts of elementary cycles tutorial all along with the key concepts of some biogeochemical cycles, respiration of plants and animals, decay of plants and animals, photosynthesis, formation of carbonic acid, conversion of carbon to tissues and shells
Theory and lecture notes of Consumption Spending all along with the key concepts of consumption spending, net taxes, disposable income, buying consumption goods, baseline level of consumption. Tutorsglobe offers homework help, assignment help and tutor’s assistance on Consumption Spending.
1931625
Questions Asked
3689
Tutors
1482758
Questions Answered
Start Excelling in your courses, Ask an Expert and get answers for your homework and assignments!!