attempt to help by katoch

ALCOHOLS
Alcohols having alkyl groups containing 5 carbons or lesser than that are soluble in water majorly due to hydrogen bonding, but in case of higher alcohols they contain hydrogen bonding along with weak wanderwaal's forces.

On adding Cl₂,H₂O to alkenes first Cl⁺ attacks then OH ^-.
attack takes place in such a way that in case of unsymmetrical alkene, Cl⁺ attacks to carbon containing more no: of hydrogen and
OH ^- attacks on the carbon having less no: of hydrogen.
THE ABOVE REACTION IS CALLED HALOHYDRIN REACTION.

IN PINACOL-PINACOLON REACTION WHY IT FAVOURS FOR THE FORMATION OF SECONDARY CARBOCATION THAN TERTIARY CARBOCATION AS WE KNOW THAT TERTIARY CARBOCATION IS THE MOST STABLE?

ANS:BECAUSE THE RESONANCE ENERGY FAVOURS THE FORMATION OF SECONDARY CARBOCATION THAN TERTIARY .

GOOD
HERE IS THE SOLUTION TO YOUR PROBLEM

WHEN H⁺ ATTACKS THE PINACOL A TERTIARY CARBOCATION FORMATION TAKES PLACE. BUT THERE TAKES PLACE 1-2 METHYL SHIFT EVEN IF THERE IS ALREADY FORMED TERTIARY CARBOCATION.AFTER METHY SHIFT, RESONANCE TAKES PLACE FOR THE FORMATION OF PINACOLONE.

THEREFORE, IT IS DUE TO THIS RESONANCE ENERGY THE FORMATION OF SECONDARY CARBOCATION TAKES PLACE.

Well you may not say favouring then, na! It is supported by resonance energy....wrong choice of word, that's all.

Lucas's test is based on the polarity of the C-OH bond which allows it to be cleaved to form a carbocation. Hence the substrates Ph-CH₂-OH and CH₂=CH-CH₂-OH give the Lucas test, as the C-OH bond is polar enough to be cleaved(forming the relatively stable benzyl and allyl cations respectively).

Oxidation Reactions of Alcohols
Simple 1º and 2º-alcohols in the gaseous state lose hydrogen when exposed to a hot copper surface. This catalytic dehydrogenation reaction produces aldehydes (as shown below) and ketones, and since the carbon atom bonded to the oxygen is oxidized, such alcohol to carbonyl conversions are generally referred to as oxidation reactions. Gas phase dehydrogenations of this kind are important in chemical manufacturing, but see little use in the research laboratory. Instead, alcohol oxidations are carried out in solution, using reactions in which the hydroxyl hydrogen is replaced by an atom or group that is readily eliminated together with the alpha-hydrogen.
The decomposition of 1º and 2º-alkyl hypochlorites, referred to earlier, is an example of such a reaction.

RCH2?OH + hot Cu RCH=O + H2
RCH2?O?Cl + base RCH=O + H?Cl
The most generally useful reagents for oxidizing 1º and 2º-alcohols are chromic acid derivatives.
Two such oxidants are Jones reagent (a solution of sodium dichromate in aqueous sulfuric acid) and pyridinium chlorochromate, C5H5NH(+)CrO3Cl(?), commonly named by the acronym PCC and used in methylene chloride solution.
In each case a chromate ester of the alcohol substrate is believed to be an intermediate, which undergoes an E2-like elimination to the carbonyl product.
The oxidation state of carbon increases by 2, while the chromium decreases by 3 (it is reduced). Since chromate reagents are a dark orange-red color (VI oxidation state) and chromium III compounds are normally green, the progress of these oxidations is easily observed.
Indeed, this is the chemical transformation on which the Breathalizer test is based. The following equations illustrate some oxidations of alcohols, using the two reagents defined here. Both reagents effect the oxidation of 2º-alcohols to ketones, but the outcome of 1º-alcohol oxidations is different. Oxidation with the PCC reagent converts 1º-alcohols to aldehydes; whereas Jones reagent continues the oxidation to the carboxylic acid product, as shown in the second reaction.
Reaction mechanisms for these transformations are displayed on clicking the "Show Mechanism" button. For the first two reactions the mechanism diagram also shows the oxidation states of carbon (blue Arabic numbers) and chromium (Roman numbers).
The general base (B:) used in these mechanisms may be anything from water to pyridine, depending on the specific reaction.

Two structural requirements for the oxidation to carbonyl products should now be obvious:
1. The carbon atom bonded to oxygen must also bear a hydrogen atom.
Tertiary alcohols (R3C?OH) cannot be oxidized in this fashion.
2. The oxygen atom must be bonded to a hydrogen atom so that a chromate ester intermediate (or other suitable leaving group) may be formed.

Ethers (R?O?R) cannot be oxidized in this fashion.
The fourth reaction above illustrates the failure of 3º-alcohols to undergo oxidation.
The second reaction mechanism explains why 1º-alcohols undergo further oxidation by Jones reagent. The aqueous solvent system used with this reagent permits hydration (addition of water) to the aldehyde carbonyl group.
The resulting hydrate (structure shown below the aldehyde) meets both the requirements stated above, and is further oxidized by the same chromate ester mechanism.

Water is not present when the PCC reagent is used, so the oxidation stops at the aldehyde stage.

Another chromate oxidizing agent, similar to PCC, is pyridinium dichromate, (C5H5NH(+) )2 Cr2O7(?2), known by the acronym PDC. Both PCC and PDC are orange crystalline solids that are soluble in many organic solvents.
Since PDC is less acidic than PCC it is often used to oxidize alcohols that may be sensitive to acids. In methylene chloride solution, PDC oxidizes 1º- and 2º-alcohols in roughly the same fashion as PCC, but much more slowly. However, in DMF solution saturated 1º-alcohols are oxidized to carboxylic acids.
In both solvents allylic alcohols are oxidized efficiently to conjugated enals and enones respectively.

1. The hydroxy derivatives of aliphatic hydrocarbons are termed alcohols. They contain one or more hydroxyl (OH) groups.
Example:
Methyl Alcohol CH-3OH
Ehtyl alcohol C-2H-5OH also written as CH-3CH-2OH
Propyl alcohol C-3H-7OH also written as CH-3CH-2CH-2OH

2. Methods of Preparation of Alcohols
1. preparation from haloalkanes
2. By reduction of aldehydes, ketones and esters
3. Physical Properties:
4. Reaction with active metals - acidic character
5. Esterification
Alcohols react with monocarboxylic acids, in the presence of concentrated sulphuric acid or dry HCL gas as catalyst, to from esters. This reaction is known as esterification.

6. Dehydration
When alcohols are heated with conc. or H3PO4, at 443 K, they get dehydrated to form alkenes.
The ease of dehydration of alcohol follows the order 3>2>1 which is also the order of stability of carbocation.

7. Oxidation
The oxidation of alcohols can be carried out by a number of reagents such as acqueous, alkaline or acidified KMnO4, acidified Na2Cr2O7, nitric acid, chromic acid, etc.
8. Reaction with sodium
The cleavage in this reaction will be in the OH bond. Alcohols react with active metals to liberate hydrogen gas and form metal alkoxide.
Ethanol or Ethyl alcohol reacts with sodium to give Sodium ethoxide and hydrogen
9. Reaction with phosphorus halides
Phosphorus halides such as PCl5, PCl3, PBr3 and PI3 react with alcohols to form corresponding haloalkanes.
10. Reaction with ZnCl2/conc.-HCl
This is a reaction or test to distinguish various categories of alcohols and is termed Lucas test.
In this test, an alcohol is treated with an equimolar mixture of concentrated hydrochloric acid and anhydrous ZnCl2 (called Lucas reagent).

11. Conversion of alcohols into aldehydes and ketones
Oxidation of primary alcohol gives aldehydes.
Oxidation of secondary alcohols gives ketones.
It is difficult to oxidize tertiary alcohols.

* ii. A dihydric alcohol contains two -OH groups in the molecule
ex. ethylene glycol
CH2OH
|
CH2OH
iii. A trihydric alcohol contains three -OH groups in its molecules
ex.glycerol
CH2OH

|
CH2OH
|
CH2OH
Monohydric alcohols are represented by the general formula R-OH or CnH2n+1OH.
Monohydric alcohols are further classified according to the carbon atom to which the hydroxyl group is attached.
1. Primary alcohols: -OH group is attached to primary carbon atom. They contain the group -CH2OH
eg.: CH3CH2OH, CH3CH2CH2OH
2. Secondry alcohol: -OH group is attached to a secondary carbon atom. It contains a divalent >CHOH group.
Ex. iso-propyl alcohol
3. Tertiary alcohol: -Oh group is attached to tertiary carbon atom. C-OH group is present
* alcohols physical props :
A. Physical state: the lower members are colourless liquids and have a characteristic smell and burning taste.
The higher members(with more than 12 carbons) are colourless wax like solids.
B. Solubility: The lower members are highly soluble in water.
Amongst isomeric alcohols, the solubility increases with branching.
C. Alcohols exists associated molecules due to intermolecular hydrogen bonds.
D. Boiling points: The lowers members have low boiling points.
With the increase in molecular weight, the boiling points keep on increasing gradually.
e. Density: Generally alcohols are lighter than water.
Density of alcohols increases with molecular mass.
F. Alcohols have intoxicating effects.
Methanol is poisonous.
Ethanol is used for drinking purposes.
ALCOHOLS ACIDIC NATURE :
Alcohols are weakly acidic in nature.
They react with active metals such as sodium, potassium, magnesium, aluminium, etc. to liberate hydrogen gas and form metal alkoxide.
Liberation of hydrogen shows that alcohols are acidic in nature.
The acidic nature of alcohols is due to the presence of polar O-H bond.
As oxygen withdraws shared electron pair between O and H atoms towards itself, it can lose the proton (H+).
However, alcohols are weak acids

http://www.chemguide.co.uk/organicprops/alcohols/background.html#top