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 info@tutorsglobe.com
identification of the fault given in a tv receiver - very the tv receiver is switched on firstly. the image on the screen with no colour. adjust the colour control. there is on the screen no colour picture.
www.tutorsglobe.com offers d-block elements & its properties homework help, d-block assignment help, online tutoring assistance, inorganic chemistry solutions by online qualified tutor's help.
tutorsglobe.com expiration assignment help-homework help by online respiration tutors
tutorsglobe.com length of stamens assignment help-homework help by online sterile stamen tutors
www.tutorsglobe.com offers nucleophilic reactions homework help, nucleophilic reactions assignment help, online tutoring assistance, organic chemistry solutions by online qualified tutor's help.
tutorsglobe.com secondary lymphoid organs assignment help-homework help by online structure and functions of immune system tutors
work, heat and heat capacity tutorial all along with the key concepts of types of process, isothermal process, adiabatic process, isochoric process, isobaric process, reversible and irreversible process
tutorsglobe.com mendels experiments assignment help-homework help by online mendels laws of inheritance tutors
tutorsglobe.com retinopathy assignment help-homework help by online optometry tutors
tutorsglobe.com objectives of fiscal policy assignment help-homework help by online fiscal policy tutors
TutorsGlobe.com Carbon and its Compounds Assignment Help-Homework Help by Online Access Chemistry Tutors
www.tutorsglobe.com offers free help with examining the initial basic feasible solution for non-degeneracy, operation research, lpp solutions, assignment help, homework help.
Interactions within Ecosystems tutorial all along with the key concepts of Types of Interactions, Predator-Prey Interaction, Symbiotic Interactions, Competition, Interspecific Competition and Intraspecific Competition
tutorsglobe.com emerging viral infections in humans assignment help-homework help by online viruses tutors
www.tutorsglobe.com offers Object Diagrams homework help, assignment help, case study, writing homework help, online tutoring assistance by computer science tutors.
1940628
Questions Asked
3689
Tutors
1471760
Questions Answered
Start Excelling in your courses, Ask an Expert and get answers for your homework and assignments!!