Friedrich Schleiermacher’s “Concerning the so-called first Letter of Paul to Timothy; a critical open letter to J. C. Gass” (1807) was a watershed piece in the history of the interpretation of the Pastoral Epistles, as he led the way in questioning the Pauline authorship of 1 Timothy. He argued particularly from the difference in vocabulary between 1 Timothy and other Pauline letters and from what he saw as an incoherent and discontinuous train of thought in 1 Timothy. Schleiermacher argued that 1 Timothy was created by drawing from 2 Timothy and Titus, whose authenticity he did not dispute.
In 1999 Hermann Patsch published a very helpful article which briefly summarized Schleiermacher’s arguments and how Schleiermacher’s work was received at the time. Patsch summarizes all the significant contemporary reviews as well as the reviews of Heinrich Planck’s book which was written as a response to Schleiermacher. I was pleased to discover the article is available online.
It was interesting to read that the early reviews of Schleiermacher were consistently negative. In fact, according to Patsch, Schleiermacher’s book was “more or less clearly torn to pieces, attacked in monographs.” De Wette was critical of several of Schleiermacher’s arguments but said: “He has seen what as yet no one saw: he demonstrates that the first letter to Timothy was not written by Paul.”
The debate seen in these reviews contains most of the same talking points found in the same debate today.
If you are doing any work on history of interpretation of the PE or the authorship question, this is a helpful article.
 Hermann Patsch, “The Fear of Deutero-Paulinism: The Reception of Friedrich Schleiermacher’s ‘Critical Open Letter’ concerning 1 Timothy,” Journal of Higher Criticism 6 (1999): 3-31
 Heinrich Ludwig Planck, Bemerkungen über den ersten Paulinischen Brief an den Timotheus in Beziehung auf das kritische Sendschreiben von Hrn. Prof. Fr. Schleiermacher (Göttingen: Röver, 1808).