This isomerism is due to the different position of the hydroxyl group in the same chain, e.g. They are obtained by treating Grignard's reagent with (i) formaldehyde (ii) ethylene oxide (iii) by dry oxygen or (iv) ethylene chlorohydrin, followed by hydrolysis of the addition product.
CH OSO 3 H
In the last example, H and OH are added to the same surface of the double bond, i.e. In this case, no intermediate carbonium ion is formed as in ordinary electrophilic addition at the double bond.
CHO H 2 , catalyst
Thus, when the transition state is approached, both the carbon atom and the electron-deficient boron atom become acidic. Thus, the reactions involve a single step with only one transition state in which hydrogen and boron both add to the carbon-carbon double bond.
OHCCH2
The hydrogen atom of one alcohol molecule is attracted to the oxygen atom of the other OH group of the other molecule and the two molecules are held together by a weak bond called a hydrogen bond, which is electrostatic in nature. In alcohols, alkyl groups have a +I effect (electron donating groups), which means that there will be an increased movement of electrons towards the oxygen atom, resulting in a difference in the acid strength of primary, secondary and tertiary alcohols.
COOH
The reaction is carried out in the presence of a dehydrating agent such as concentrated sulfuric acid or dry hydrogen chloride. Esterification is a reversible reaction and therefore, water is removed as soon as it is formed to prevent the reaction from going in the reverse direction.
H 5 Ethyl acetate
In this case, the hydrogen atom of the hydroxyl group combines with the alkyl group of the Grignard reagent and forms an alkane. The least reactive of the hydrogen halides, HCl, requires the presence of zinc chloride for reaction with primary and secondary alcohols.
CH 2 OH Ethanol
Phosphorus tribromide and phosphorus triiodide react with alcohols to give very good yields of alkyl halides.
CH 2 I Ethyl iodide
CH 3HOZnCl2-
The products differ depending on the type of alcohol and oxidizer used. alcohol requires strict conditions and results in a mixture of products.
COOH Acetic acid
The oxidation of alcohols to carboxylic acids has recently been used as a breathalyzer test to detect the level of ethanol in the breath (and therefore blood) of suspected alcohol-intoxicated persons, especially drivers. Any alcohol present in the breath is oxidized to acetic acid, leading to a change in color from orange to green in the tube.
R CNO 2
The distillate from step (a) consists of methyl alcohol and acetone and is dried over lime and then subjected to fractional distillation. The solid compound is separated and decomposed by heating with water to form methyl alcohol. It is then exposed to a pressure of 200 atmospheres and passed over a catalyst (a mixture of Zn, Cr and Cu oxides) at 350-400°C, when methyl alcohol is obtained.
The mixture is then passed through a copper tube at 200 °C under a pressure of 100 atmospheres, when methyl alcohol is obtained.
Methane
It is a brown aqueous distillate and is collected as the top layer in the settling tank. It is left as a residue in the iron retorts and used as domestic fuel. The crude methyl alcohol thus obtained is treated with anhydrous CaCl2, when a solid crystalline compound of the composition, CaCl2.4CH3OH, is formed, leaving acetone.
The mixture is then passed through a copper tube at 200°C under a pressure of 100 atmospheres when methyl alcohol is obtained. i) Methyl alcohol is a colorless flammable liquid, b.p. ii) It has a pungent vinous odor and has a burning taste. iii).
CHO +
It is a mixture of alcohols and is used in the manufacture of amyl acetate, a valuable solvent. It is a solid mass left after the distillation of the wash and is used as cattle feed. It also dissolves inorganic substances such as NaOH, KOH and sulfur. v) It has a specific intoxicating effect on the system.
Under the name Petrobol, it is used as a solvent in cosmetics and hair tonics.
CHOHCH 2
CH 2 I KCN
CH 2 COOH NH 3
CH 2 CONH 2 HNO 2
Since ethylene glycol has two hydroxyl groups, it participates in hydrogen bonding more efficiently than the monohydric alcohols. Ethylene glycol is hygroscopic and miscible with water and alcohol in all proportions but insoluble in ether. Ethylene glycol got its use as an antifreeze (under the name Prestone) due to its high boiling point, low freezing point and higher solubility in water.
Ethylene glycol has two primary alcohol groups in its molecule and, therefore, exhibits the properties of a primary alcohol to a double degree.
OH CHO
OH COOH
With KMnO4 or K2Cr2O7 the bond between the two hydroxylated carbon atoms breaks to give carboxylic acid. Compounds containing two or more –OH or >C=O groups attached to adjacent carbon atoms undergo cleavage of carbon bonds during oxidation with periodic acid. Since this oxidation is almost quantitative, valuable information is obtained from the amount of periodic acid used and from the nature and quantity of the products formed.
CHOH
Oxidation with Lead tetracetate, Pb(OAc) 4
As in most 1,2 displacements in electron-deficient atoms, the migrating group is never completely free. It does not detach from the leaving carbon until it has joined the electron-deficient carbon. An important class of acetals or cyclic ketals also called dioxanes is obtained when α-glycols react with aldehydes or ketones in the presence of p-toluenesulfonic acid.
It occurs in nature in oils and fats, which are mixtures of glycerol esters (glycerides) with higher fatty acids and unsaturated acids.
CH CH 2 Propylene
COOH CO CHOH
OH CHOH
ONO 2 CHONO 2
OH CHCl
OOC CH-OOC
CHOH
CH CH2 CHO Acrolein H unstable. i) From the analytical data it is known that the molecular formula of glycerin is C3H8O3. ii) Since it forms a triacetyl derivative during acetylation, it indicates the presence of three hydroxyl groups. iii). The main use of glycerin is in the production of nitroglycerin which is highly explosive. ii) Because of its non-drying character, glycerine is used in the manufacture of non-drying printing inks, shoe tanning, for filling gas meters and for preserving fruits. Due to its high viscosity, glycerin is used as a lubricant for watches and clocks. iv).
It is produced by gradually adding glycerin to a cold mixture of fuming nitric acid and concentrated sulfuric acid.
CH2ONO 2
Since two hydroxyl groups cannot be attached to the same carbon atom in a stable compound, three hydroxyl groups, one each, must be attached to three carbon atoms. Aromatic compounds containing one or more hydroxyl groups (-OH) directly attached to a benzene ring are known as aromatic hydroxyl compounds. If only one hydroxyl group is present in the benzene nucleus, the compounds are known as monohydric phenols.
Phenolo-Cresolm-Cresol
In recent years, a new method has been developed for the synthesis of phenol from cumene or isopropyl benzene. The rearrangement involved in the conversion of cumene hydroperoxide to phenol is a 1,2 shift to an electron-deficient oxygen atom when the phenyl group is linked to carbon in the peroxide and to oxygen in the phenol. Protonated peroxide loses a molecule of water to form an intermediate in which oxygen carries only six electrons.
At the same time, a 1, 2 shift of the phenyl group from carbon to electron-deficient oxygen occurs, yielding carbonium ions.
CO Phenol
The phenoxide ion is more stabilized at resonance than the non-ionized molecule due to delocalization of the negative charge alone. In the unionized molecule, charges are spread opposite to the phenoxide ion, increasing its energy and decreasing its stability. Thus, the equilibrium of the reaction from phenol to phenoxide will prefer to proceed in the forward direction.
The hydrogen atom of the hydroxyl group is replaced by the corresponding acyl group (RCO-).
AlCl3
OAlCl3
AlCl 2
AlCl2
Dil. HNO3
The mixture of p-nitrophenol and o-nitrophenol can be separated by steam distillation due to difference in their boiling points. p. -Nitrophenol is less volatile due to intermolecular hydrogen bonding, while o-nitrophenol is more volatile due to intramolecular hydrogen bonding. If halogenation is carried out in a solvent with low polarity, such as chloroform, CCl4 or CS2, reaction can be limited to mono halogenation.
When reduced by hydrogen at 160 °C in the presence of finely divided nickel (catalyst), it forms cyclohexanol.
AlCl3
The Claisen rearrangement is an example of pericyclic reactions and belongs to the [3.3]-sigmatropic rearrangement category. The allyl group migrates from the ether oxygen to the ring carbon ortho to it.
CH CHR
- No. Ring size Common name of the class
The reaction proceeds through a cyclic six-membered transition state in which the breaking of the oxygen-allyl bond is synchronous with the formation of a carbon-carbon bond at an ortho position. In the case of mixed ethers, the higher alkyl group determines the name of the parent hydrocarbon while the lower one forms the alkoxy group. Epoxides (oxiranes) are cyclic three-membered ethers, usually formed by peroxyoxidase oxidation of the corresponding alkenes.
The common name of an epoxide is formed by adding "oxide" to the name of the alkene being oxidized, e.g.
Oxolane
A recent application of Williamson's synthesis is a Williamson-type intramolecular reaction in which a 2-bromo hydroperoxide cyclizes to give 1,2-dioxocyclobutane (1,2-dioxetane).
O C2H5 H2SO4 Ethyl alcohol Ethyl hydrogen sulfate. i) The two C-O bonds in ethers are at an angle of about 110-132° (not linear) depending on the alkyl substitution, so the dipole moments of two C-O bonds do not cancel each other. In host-guest chemistry, an inclusion compound is a complex in which one chemical compound the host forms a cavity when molecules of a second compound ie. the gas is located. In general, the stereochemistry of this method is the same as that observed in the peroxyacid oxidation of alkenes.
Substituents that are cis to each other in the alkene remain cis in the epoxide due to halohydrin formation.
X Reactions of epoxides
- OHRLiH2CCH2
- CH 2 CH 2 CH 3 CH 3 CH 2 CH 2 CH 2 SCH 2 CH 2 OH ethanol-water, 0 0 C 2-(Butylthio)ethanol
- CH 2 OHH3O+
- OHCl
- OsO4
Predict the product you would expect from the reaction of NaBH4 with the following compounds. Discuss the following properties of alcohols:. ii) Reaction with halogen acids. iii) Reaction with phosphorus trihalides. iv) Reaction with alkali metals. Predict the products of the following reactions:. boiling hydrochloric acid sulfuric acid. ii) ethyl alcohol (iii) tert-butyl alcohol.
When one mole of each of the following compounds is treated with HIO4, what will be the product and how many moles of HIO4 will be consumed. i) CH3CHOHCH2OH (ii) HOCH2CHOHCHOHCH3.
