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Exhibit 31.1
 CERTIFICATION PURSUANT TO
SECTION 302 OF
THE SARBANES-OXLEY ACT OF 2002
  1.
    
    I have reviewed this Quarterly Report on Form 10-Q for the quarter ended March 31, 2007 of
Enzon Pharmaceuticals, Inc. (Enzon);
 2.
    
    Based on my knowledge, this report does not contain any untrue statement of a material fact
or omit to state a material fact necessary to make the statements made, in light of the
circumstances under which such statements were made, not misleading with respect to the period
covered by this report;
 3.
    
    Based on my knowledge, the financial statements, and other financial information included in
this report, fairly present in all material respects the financial condition, results of
operations and cash flows of the registrant as of, and for, the periods presented in this
report;
 4.
    
    The registrants other certifying officer and I are responsible for establishing and
maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and
15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules
13a-15(f) and 15d-15(f)) for the registrant and have:
 (a)
    
    designed such disclosure controls and procedures, or caused
such disclosure controls and procedures to be designed under our supervision,
to ensure that material information relating to the registrant, including its
consolidated subsidiaries, is made known to us by others within those entities,
particularly during the period in which this report is being prepared;(b)
    
    designed such internal control over financial reporting, or
caused such internal control over financial reporting to be designed under our
supervision, to provide reasonable assurance regarding the reliability of
financial reporting and the preparation of financial statements for external
purposes in accordance with generally accepted accounting principles;(c)
    
    evaluated the effectiveness of the registrants disclosure
controls and procedures and presented in this report our conclusions about the
effectiveness of the disclosure controls and procedures, as of the end of the
period covered by this report based on such evaluation; and(d)
    
    disclosed in this report any change in the registrants
internal control over financial reporting that occurred during the registrants
most recent fiscal quarter (the registrants fourth fiscal quarter in the case
of an annual report) that has materially affected, or is reasonably likely to
materially affect, the registrants internal control over financial reporting.
 5.
    
    The registrants other certifying officer and I have disclosed, based on our most recent
evaluation of internal control over financial reporting, to the registrants auditors and the
Audit Committee of the registrants board of directors (or persons performing the equivalent
functions):
 (a)
    
    All significant deficiencies and material weaknesses in the
design or operation of internal control over financial reporting which are
reasonably likely to adversely affect the registrants ability to record,
process, summarize and report financial information; and
 (b)
    
    Any fraud, whether or not material, that involves management or
other employees who have a significant role in the registrants internal
control over financial reporting.
 May 4, 2007
    By:

/s/ Jeffrey H. BuchalterJeffrey H. BuchalterPresident and Chief Executive Officer
(Principal Executive Officer) 27