Method for preparation of alkyl-substituted butadienes
AssigneePhillips Petroleum Company
InventorHarold M. Hawkins, deceased
Life of this patent
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Abstract
A method for forming monoolefinic alcohols and optionally alkyl-substituted conjugated dienes. A lower alcohol is oxidized to the aldehyde, and the aldehyde separated from the product mixture by reaction with a monoolefinic alcohol to form a hemialdehyde. An aliphatic isomonoolefin is reacted with a portion of the hemialdehyde stream, to form additional unsaturated monoolefinic alcohol as product, and for recycle to the aldehyde recovery step. The unsaturated monoolefinic alcohol can be dehydrated to an alkyl-substituted conjugated diene such as isoprene.
Claims21
A method for the preparation of alkyl-substituted butadienes which comprises the steps:
- a. oxidizing a lower alkanol at least in part to the corresponding lower aldehyde,
- b. contacting said lower aldehyde with an aliphatic hydrocarbyl monoolefinic alcohol, thereby forming a hemialdehyde,
- c. contacting said hemialdehyde with an aliphatic hydrocarbyl isomonoolefin represented by:
- ##STR8## wherein each R is hydrogen or a saturated hydrocarbon aliphatic radical of up to 3 carbon atoms per R group, under reaction conditions, thereby forming said aliphatic hydrocarbyl monoolefinic alcohol,
- d. recycling a portion of said aliphatic monoolefinic alcohol to said contacting step (b), and
- e. dehydrating under dehydration conditions at least a further portion of said aliphatic monoolefinic alcohol under dehydration conditions, thereby forming said alkyl-substituted butadiene.
A process for preparing isoprene which comprises the steps of:
- a. oxidizing methanol to form a formaldehyde stream comprising formaldehyde, unreacted methanol, and water,
- b. contacting said formaldehyde stream with a 3-methyl-3-buten-1-ol stream, thereby forming a hemiformal stream comprising the hemiformal of 3-methyl-3-buten-1-ol, unreacted methanol, water, and unreacted 3-methyl-3-buten-1-ol,
- c. separating said hemiformal stream into streams comprising unreacted methanol, water, 3-methyl-3-buten-1-ol, and a hemiformal concentrate,
- d. contacting said hemiformal concentrate with isobutene, thereby producing a 3-methyl-3-buten-1-ol stream further comprising unreacted isobutene,
- e. separating said 3-methyl-3-buten-1-ol stream into streams comprising recycle isobutene, and 3-methyl-3-buten-1-ol,
- f. recycling at least a portion of said 3-methyl-3-buten-1-ol to said contacting step (b) with said formaldehyde stream,
- g. recycling said unreacted isobutene to said step (d), and
- h. dehydrating a further portion of said 3-methyl-3-buten-1-ol to said isoprene.
A method for forming alkyl-substituted butadiene, which comprises:
- oxidizing a lower monoalcohol-air mixture to form a first stream comprising an aldehyde, unoxidized monoalcohol, and water,
- contacting said first stream with a recycle stream of monoolefinic alcohol effective to react with said aldehyde to form a hemialdehyde,
- recovering therefrom a second stream comprising a hemialdehyde, unoxidized monoalcohol, and water,
- separating said second stream into a third stream comprising water and lower monoalcohol, and a fourth stream comprising a hemialdehyde concentrate,
- reacting said hemialdehyde in said fourth stream with an isomonoolefin effective to thereby produce monoolefinic alcohol,
- recycling a portion of said monoolefinic alcohol as said recycle monoolefinic alcohol for the formation of further said hemialdehyde, and
- dehydrating at least a further portion of said monoolefinic alcohol, thereby forming said alkyl-substituted butadiene.
In the step of removing lower aldehydes from a crude oxidation mixture derived from the oxidation of a lower alkanol and comprising aldehyde, water, and unreacted lower alkanol, the improvement which comprises
- contacting said crude oxidation mixture with recycle aliphatic monoolefinic alcohol represented by:
- ##STR12## wherein each R is hydrogen or a saturated hydrocarbon aliphatic radical of 1 to 3 carbon atoms, thereby forming a hemialdehyde stream containing the hemialdehyde of said aldehyde and said aliphatic monoolefinic alcohol, unreacted aldehyde, water, and unreacted lower alcohol,
- separating a hemialdehyde concentrate from said hemialdehyde stream,
- contacting said hemialdehyde concentrate with an aliphatic hydrocarbyl monoolefin represented by:
- ##STR13## thereby forming aliphatic monoolefinic alcohol, recycling a portion of said aliphatic monoolefinic alcohol as said recycle aliphatic monoolefinic alcohol, and
- dehydrating a further portion of said aliphatic monoolefinic alcohol to the corresponding alkyl-substituted butadiene.
Dependencies are inferred from the claim text.