The time for completion of a Ph.D. varies, four to six years is typical. A sample timeline under the Research First program is broken down in milestones for students as below. More details of Ph.D. requirements can be found in the New Red Book.
First year (G1): complete core course in Chemistry; selection of a lab & a supervisory committee; first year of seminar
Summer before first semester (optional): research rotations
First Semester: research rotations; selection of a lab; take core courses
Second Semester: selection and first meeting of supervisory committee; selection of course work for Program of Study.
Second year (G2): continue/complete all course work; start taking cumulative exams; Research Update Interview (RUI).
First Semester: Research Update Interview with supervisory committee for progress assessment and classification; start taking cumulative exams
Second Semester: complete seminar requirement
Third year (G3): complete cumulative exams; Original Proposal Oral exam (OPO)
First Semester: complete cumulative exams
Second Semester:Original Proposal Oral exam with supervisory committee.
Fourth year (G4): evaluate research progress
Second Semester: meeting with supervisory committee; discussion of time to graduation
Complete research; write thesis; final defense of thesis work and examination by supervisory committee; Ph.D. conferred