Here's 4 Alexander Donaldsons born to Alexander Donaldsons all born 1832 +/- 5 years. (from BVRs)
DONALDSON, Alexander Archibald
Gender: Male
Birth Date: 14 Aug 1827
Birthplace: Kirkcudbright, Kirkcudbright, Scotland
Recorded in: Kirkcudbright, Kirkcudbright, Scotland
Father: Alexander Christison DONALDSON
Mother: Jane HOPE
Source: FHL Film 1068032 Dates: 1743 – 1854
DONALDSON, Alexander
Gender: Male
Birth Date: 10 Apr 1831
Birthplace: Edinburgh Parish, Edinburgh, Midlothian, Scotland
Recorded in: Edinburgh, Midlothian, Scotland
Father: Alexander DONALDSON
Mother: Janet SIMPSON
Source: FHL Film 1066691 Dates: 1809 – 1855
DONALDSON, Alexander
Gender: Male
Birth Date: 11 Jul 1832
Christening Date: 5 Aug 1832
Recorded in: Cupar, Fifeshire, Scotland
Father: Alexander DONALDSON
Mother: May LAMONT
Source: FHL Film 1040101 Dates: 1778 – 1855
DONALDSON, Alexander
Gender: Male
Birth Date: 6 Sep 1835
Birthplace: Associate Congregation, Perth, Perth, Scotland
Recorded in: Perth, Perthshire, Scotland
Collection: Associate Session Congregation
Father: Alexander DONALDSON
Mother: Euphemia WILKIE
Source: FHL Film 889486 Dates: 1743 - 1854
I hope one of these might be the one you're looking for. Good Luck!
Anne