using System;

using System.Collections.Generic;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        string json = @"

            {  

                ""d"" : {

                 ""humidity"": ""39.21"",

                 ""acc_y"": ""1.21"",

                 ""ambient_temp"": ""24.21"",

                 ""air_pressure"": ""1029.21"",

                 ""object_temp"": ""23.21"",

                 ""acc_z"": ""0.21"",

                 ""acc_x"": ""3.21"",

               } 

            }";

        Dictionary<string, object> obj = JsonConvert.DeserializeObject<Wrapper>(json).d;

        foreach (var kvp in obj)

        {

            Console.WriteLine(kvp.Key + ": " + kvp.Value);

        }

    }

}

​

class Wrapper

{

    public Dictionary<string, object> d { get; set; }

}

​