Updating record through ajax


i am trying to update a record using ajax. but i am receiving 500 internal server error. i have tried in many ways . but no luck . here is my code:

var data = { 
	{'phone' : '98987987'} 

$.ajax( {
url: ‘https://api.knackhq.com/v1/objects/object_20/records/5466cb10444a2dc26c95fe0a’,
type: “PUT”,
headers: {
“X-Knack-Application-Id”: “XXXXXXXXXXXXX”,
data: data, success: function(response) {
alert(‘Record Added!’); Knack.hideSpinner();

i am checking this api using chrome api testing tool. but same thing happens.i am giving a screenshot .

thanks for your help