Separation of t-amyl alcohol from isobutanol by extractive distillation

• US 4,693,788 A
• Filed: 03/17/1987
• Issued: 09/15/1987
• Est. Priority Date: 03/17/1987
• Status: Expired due to Fees

• Current Assignee: Lloyd Berg, Michael J. Shanahan
• Original Assignee: Lloyd Berg, Michael J. Shanahan
• Inventors: Berg, Lloyd, Shanahan, Michael J.
• Primary Examiner(s): BASCOMB JR, WILBUR
• Application Number:
  US07/026,451
• Time in Patent Office: 182 Days
• Field of Search: 203/60, 203/51, 203/61, 203/57, 203/64, 203/56, 568/913, 568/918
• US Class Current: 203/51
• CPC Class Codes: C07C 29/84 by extractive distillation
• CPC Class Codes: C07C 31/12 containing four carbon atoms
• CPC Class Codes: C07C 31/125 containing five to twenty-two carbon atoms

Abstract

t-Amyl alcohol and isobutanol cannot be separated from each other by distillation because of the proximity of their boiling points. t-Amyl alcohol can be readily separated from isobutanol by using extractive distillation in which the extractive agent is a higher boiling organic compound or a mixture of two or more of these. Typical examples of effective agents are: dimethylformamide; N,N-dimethylacetamide; N,N-dimethylacetamide and dimethylsulfoxide; dimethylformamide, N,N-dimethylacetamide and phthalic anhydride.

Claims

1. A method for recovering t-amyl alcohol from a mixture of t-amyl alcohol and isobutanol which comprises distilling a mixture of t-amyl alcohol and isobutanol in a rectification column in the presence of about one to two parts of extractive agent per part of t-amyl alcohol-isobutanol mixture, recovering the t-amyl alcohol as overhead product and obtaining the extractive agent and isobutanol from the stillpot, the extractive agent comprises dimethylformamide.

2. The method of claim 1 in which the extractive agent comprises dimethylformamide and at least one material from the group consisting of acetamide, benzoic acid, N,N-dimethylacetamide, phthalic anhydride, and hexahydrophthalic anhydride.

3. A method for recovering t-amyl alcohol from a mixture of t-amyl alcohol and isobutanol which comprises distilling a mixture of t-amyl alcohol and isobutanol in a rectification column in the presence of about one to two parts of extractive agent per part of t-amyl alcohol-isobutanol mixture, recovering the t-amyl alcohol as overhead product and obtaining the extractive agent and isobutanol from the stillpot, the extractive agent comprises N,N-dimethyacetamide.

4. The method of claim 3 in which the extractive agent comprises N,N-dimethylacetamide and at least one material from the group consisting of acetamide, dipropylene glycol dibenzoate, phthalic anhydride and trimellitic anhydride.