{
	"@odata.context": "https://portal.xpertdoc.com/odata4/v6/$metadata#ContentLibraries/$entity",
	"ContentLibraryId": "00000000-0000-0000-0000-000000000000",
	"Name": "Content Library Name",
	"Description": null,
	"Metadata": null,
	"CreatedByUserProfileId": "00000000-0000-0000-0000-000000000000",
	"CreatedDate": "2016-01-01T00:00:00.0000000Z",
	"ModifiedByUserProfileId": "00000000-0000-0000-0000-000000000000",
	"ModifiedDate": "2016-01-01T00:00:00.0000000Z",
	"Timestamp": "AAAAAAAEqeM="
}

var contentLibrary = portalContext.ContentLibraries.Where(cl => cl.Name == "Content Library Name").FirstOrDefault();


contentLibrary.Name = "New Name";
contentLibrary.ValueToChange = value;
	
portalContext.UpdateObject(contentLibrary);
portalContext.SaveChanges();