You Do Need power plug adapter while traveling from Dominican Republic to Brazil.

Here is Why You Need An Adapter

The outlet and plug type used in Brazil are C and N and in Dominican Republic are A, B and C. This is how they look like.

Dominican Republic

In Dominican Republic, outlets of type A, B and C are in use.

Type A

Type B

Type C

Brazil

In Brazil, outlets of type C and N are in use.

Type C

Type N