<button class="button--red">BUTTON</button><br>
<button class="button--blue">BUTTON</button><br>
<button class="button--green">BUTTON</button><br>
<button class="button--white">BUTTON</button><br>
<button class="button--yellow">BUTTON</button>

$colors : (red:#ff0000, blue:#0000ff, green:#00ff00, white:#ffffff, yellow:#ffff00)
@each $name, $color in $colors
    .button--#{$name}
        background-color: #{$color}