[JsonProperty("title",Required=Required.Always,Order=1)]
public string Title { get; set; }

[JsonProperty("date",Order=3)]
[JsonConverter(typeof(IsoDateTimeConverter))]
public DateTime Date { get; set; }

[JsonProperty(Order=2)]
[JsonConverter(typeof(TypeIdentifierJsonConverter))]
public TypeIdentifier DocTypeIdentifier { get; set; }

public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
    TypeIdentifier docTypeId;
    id= (TypeIdentifier) value;

    writer.WritePropertyName(id.ParameterName);
    writer.WriteValue(id.Value);
}

[JsonObject(MemberSerialization.OptIn)]
class Document
{
    [JsonProperty("title", Required = Required.Always, Order = 1)]
    public string Title { get; set; }

    [JsonProperty("date", Order = 3)]
    [JsonConverter(typeof(IsoDateTimeConverter))]
    public DateTime Date { get; set; }

    [JsonProperty(Order = 2)]
    public TypeIdentifier DocTypeIdentifier { get; set; }

    public string OtherStuff { get; set; }
}

class TypeIdentifier
{
    public string Value { get; set; }
    public string ParameterName { get; set; }
}

class DocumentConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return (objectType == typeof(Document));
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        Document doc = (Document)value;

        // Create a JObject from the document, respecting existing JSON attribs
        JObject jo = JObject.FromObject(value);

        // At this point the DocTypeIdentifier is not serialized correctly.
        // Fix it by replacing the property with the correct name and value.
        JProperty prop = jo.Children<JProperty>()
                           .Where(p => p.Name == "DocTypeIdentifier")
                           .First();

        prop.AddAfterSelf(new JProperty(doc.DocTypeIdentifier.ParameterName,
                                        doc.DocTypeIdentifier.Value));
        prop.Remove();

        // Write out the JSON
        jo.WriteTo(writer);
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        throw new NotImplementedException();
    }
}

JsonSerializerSettings settings = new JsonSerializerSettings();
settings.Converters.Add(new DocumentConverter());

string json = JsonConvert.SerializeObject(doc, settings);

class Program
{
    static void Main(string[] args)
    {
        Document doc = new Document
        {
            Title = "How to write a JSON converter",
            Date = DateTime.Today,
            DocTypeIdentifier = new TypeIdentifier
            {
                ParameterName = "type_id",
                Value = "26"
            },
            OtherStuff = "this should not appear in the JSON"
        };

        JsonSerializerSettings settings = new JsonSerializerSettings();
        settings.Converters.Add(new DocumentConverter());
        settings.Formatting = Formatting.Indented;

        string json = JsonConvert.SerializeObject(doc, settings);
        Console.WriteLine(json);
    }
}

{
  "title": "How to write a JSON converter",
  "type_id": "26",
  "date": "2014-03-28T00:00:00-05:00"
}