string result ="{"AppointmentID":463236,"Message":"Successfully Appointment Booked","Success":true,"MessageCode":200,"isError":false,"Exception":null,"ReturnedValue":null}"
dynamic d = JsonConvert.DeserializeObject<dynamic>(result);
d.GetType () は Newtonsoft.Json.Linq.JObject です
JObjectの代わりに動的オブジェクトにデシリアライズする方法