static void Main(string[] args)
		{
			var s = ReplaceStr("''adsasdasd'dsfsdf  sdfsdfdsf'asdasdasdasd''");
		}

		private static string ReplaceStr(string str)
		{
			var regExpPattern = @"^\s*'?|'?\s*$"; 
			
			var re = new Regex(regExpPattern);
			if (re.IsMatch(str))
			{
				str = re.Replace(str, "\\'");
			}
			return str;
		}

var regExpPattern =@"(['])(.*?)(?<!\\)";