-H and -OH are removed from adjacent carbon atoms of the same alcohol to produce an alkene and H2O

H+ catalyst

  H  OH. 

  |  |  

-C-C-

  |  | 

Becomes

C=C + H2O

The major product is the one that forms by removing the hydrogen from the carbon atom that has the smaller number of hydrogen atoms.

2-butanol 90% becomes 2-Butene, 10% 1-Butene

CH3-CH-CH-CH3

|   |

  H   OH

CH3-CH=CH-CH3 + H2O (90%)

Dehydration of 2 alcohols.  Ether remains and H2O

CH3-OH + CH3-OH -> CH3-O-CH3 + H2O

Methanol  Methanol         Dimethyl Ether  

One H is removed, on -OH is removed forming H2O.  The 2 alcohols are bound to the remaining ether. 

Remove 2 hydrogen atoms, one from -OH and one from the carbon bonded to the -OH.  The oxygen that makes the H2O is taken from the Oxidizing agent.

Methanol       Methanal         

CH3-OH [O] -> H-C-H + H2O

             ||

             O

One hydrogen removed from the -OH and one from the cabon bonded to the -OH group.  Ketone with a carbon-oxygen double bond attached to the alkyl groups on both sides.  Water is formed from the 2 -H removed and an O from the oxidizing agent.

CH3-CH-CH3 [O] -> CH3-C-CH3 + H2O    

    |                         ||                  

O                         O               

An additional O  adds to the aldehyde attached to the hydrogen remaining.  The O is taken from the oxidizing agent.

Acetaldehyde   Ecetic Acid

CH3-C-H [O] -> CH3-C-OH

    ||                     ||  

  O                     O

2 thiols [O] combine to create a disulfide + water

Oxidation through loss of Hydrogen atoms

CH3-S-H + CH3-S-H [O] -> CH3-S-S-CH3 + H2O

Methanethiol x2              Dimethyl disulfide