user: Question: Which formula has Thial as a chemical class?
Columns: ['Chemical class', 'Group', 'Formula', 'Prefix', 'Suffix']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Thiol', 'Sulfhydryl', 'RSH', 'sulfanyl- (-SH)', '-thiol']
SQL:

assistant: SELECT "Formula" FROM "Table" WHERE "Chemical class" = 'Thial';