The following will save to the current user's desktop. Note that you should be using the document's name not the fullname, which includes the path. Where the document has not been saved, the PDF will be saved as Documentn.pdf
Code:
Sub Print1()
'
' Silent Save_to_PDF Macro
Dim strPath As String
Dim strName As String
strPath = Environ("USERPROFILE") & "\Desktop\"
strName = Replace(ActiveDocument.Name, ".docx", ".pdf")
ActiveDocument.ExportAsFixedFormat _
OutputFileName:=strPath & strName, _
ExportFormat:=wdExportFormatPDF, _
OpenAfterExport:=False, _
OptimizeFor:=wdExportOptimizeForPrint, _
Range:=wdExportAllDocument, _
Item:=wdExportDocumentContent, _
IncludeDocProps:=False, _
KeepIRM:=True, _
CreateBookmarks:=wdExportCreateNoBookmarks, _
DocStructureTags:=True, _
BitmapMissingFonts:=True, _
UseISO19005_1:=False
End Sub