I'm trying to make my image into grayscale 100% while hovering the button. The problem is it does not become greyscale image while hovering the Button. I have tried to use :active,:hover but it doesn't solve my issue. 
#image1:hover {
   filter: grayscale(100%);
}
.button1 {
  position: absolute;
  width: 500px;
  left:0;
  top: 180px;
  text-align: center;
  opacity: 0;
  transition: opacity .35s ease;
}
.button1 a {
  width: 200px;
  padding: 12px 48px;
  text-align: center;
  color: #ff991e;
  border: 1px solid #ff991e;
  z-index: 1;
  text-decoration: none;
  font-weight: bolder;
}
.image-1:hover .button1 {
  opacity: 1;
}
div.button1:hover > #image1 {
  filter: grayscale(100%);
}<div class="col-md-6 image-1">
  <img src="http://servesphere.com.ph/moto/wp-content/uploads/2017/12/Left-image.png" class="" id="image1" style="width: auto; height: 320px;">
  <div class="centered">
    <p class="title1">BRAND NEW</p>
    <div class="button1"><a href="#"> ENTER </a></div>
  </div>
</div> 
     
    