Orgchem Alcohols

In ALCOHOLS, a hydroxyl (—OH) group is connected to a carbon atom.
In PHENOLS, the —OH group is connected to a benzene ring.
- Example of a parent molecule in phenols: PhOH (C6H5OH).
When two carbon groups are connected by single bonds to an oxygen, it is classified as an ETHER functional group.

Thiols: Sulfur analogs of alcohols.
Alcohols are organic compounds with an –OH (hydroxyl) group bonded to a saturated carbon atom; the –OH group is the functional group.
It must be emphasized that the hydroxyl group (—OH) should not be confused with the hydroxide ion (OH−).
Alcohols are not hydroxides; hydroxides are ionic compounds, while alcohols are molecular compounds.
The –OH group is covalently bonded to a saturated hydrocarbon.
Alcohols can be viewed structurally as:
- Alkyl derivatives of water: H-Ö-H becomes R-Ö-H
- Hydroxyl derivatives of alkanes: R-H becomes R-OH

Step 1: Name the longest carbon chain to which the hydroxyl (—OH) group is attached.
Step 2: The chain name is obtained by dropping the final '-e' from the alkane name and adding the ending '-ol.'
Step 3: Number the longest chain to give the lowest number to the carbon bearing the hydroxyl group.
Step 4: Indicate the position of the hydroxyl group by the number of the carbon it's attached to.
Step 5: Locate and name any other substituents.
Step 6: Combine the names and locations of substituents, the hydroxyl group location, and the longest chain name into the final name.

Example structures with names:
  - CH3-CH2-CH2-CH2-CH2-OH: 1-pentanol
  - CH3-CH-CH2-CH2-CH3: 3-pentanol
  - CH3-CH2-CH-CH-CH3 with two branches: 2,3-dimethyl-1-pentanol
  - CH3-CH2-(C2H5) with a -CH2OH group: 2-ethyl-1-pentanol

When alcohol has more than one —OH group, a counting prefix (di-, tri-, tetra-) is placed in front of the suffix -ol (diol, triol, tetraol).
The final 'e' of the parent hydrocarbon may not be dropped in such cases (e.g., 1,2-propanediol).
Position of each alcohol group is indicated by carbon numbers separated by commas (e.g., 1,3-butanediol).

Hydrogen Bonds: Alcohol molecules exhibit both polar and nonpolar character.
- The hydroxyl group is polar, while the alkyl group is nonpolar.
Boiling Point: Alcohols exhibit higher boiling points than their alkane counterparts of the same molecular weight due to hydrogen bonding.
Solubility: Rule of thumb: "like dissolves like." Alcohols align with polar solvents while longer carbon chains decrease solubility due to nonpolar characteristics.

Via Hydration of Alkenes: Alkenes react with water in the presence of sulfuric acid to form an alcohol.
- Example: $CH_2=CH_2 + H_2O <br>ightarrow CH_2CH_3OH$
- Markovnikov's Rule: This rule is applied to determine the predominant alcohol product.
Via Reduction of Aldehydes and Ketones: This involves the addition of hydrogen to the carbonyl group.
- Normal representations and products were specified throughout the reduction examples (e.g., ethanol produced from ethanol).
Catalyst used usually: finely divided platinum, palladium, or nickel; alternatively, treatments with sodium borohydride (NaBH4) or lithium aluminum hydride (LiAlH4).

Combustion: Alcohols combust completely in oxygen to produce carbon dioxide and water.
- E.g.: $C_2H_5OH + 3O_2 <br>ightarrow 2CO_2 + 3H_2O$
- Incomplete combustion produces carbon monoxide or soot.
Dehydration: A chemical reaction in which components of water (H and OH) are removed. It can be intramolecular or intermolecular.
- Intramolecular dehydration forms alkenes and occurs at high temperatures (180°C with H2SO4 as a catalyst).
- The major product follows Zaitsev’s Rule.
Oxidation: Primary alcohols can be converted to aldehydes and further to carboxylic acids; secondary alcohols yield ketones; tertiary alcohols yield no reaction. Oxidation agents include KMnO4, K2Cr2O7, H2CrO4.
Halogenation: Alcohols can react with hydrogen halides to produce alkyl halides under acidic conditions (order of reactivity: 3° > 2° > 1°).

An organic compound with an -OH group attached to a carbon that is part of an aromatic ring.
General formula: Ar-OH, where Ar represents an aryl group.

Derived from phenyl and alcohol; the parent name is phenol.
Hydroxyl group (—OH) is given the first priority in numbering, and its position is always considered as carbon 1.
Examples of substituted phenols:
- 2-Fluorophenol, 3-ethyl-2-methylphenol, 2,5-dichlorophenol, ortho-cresol, meta-cresol, para-cresol.

Both alcohols and phenols exhibit similar functional groups; however, their chemical properties can differ significantly.
Phenols have higher boiling points compared to hydrocarbons of equal molecular weight.
Phenols show weak acidity in solution and can react with metals to form phenoxides, demonstrating similarity in behavior to carboxylic acids but lack in dehydration reactions.

Used as antiseptics and disinfectants. For example, 2% phenol solution acts as an antiseptic (kills microorganisms in living tissue), while other phenolic compounds are used in disinfectants (such as Lysol).
Vitamin E and other phenolic compounds exhibit antioxidant properties.
Compounds like thymol, eugenol, and vanillin highlight the flavoring aspects and functional uses of phenolic compounds in various applications, including culinary and medicinal fields.