JPH0587595B2 - - Google Patents
Info
- Publication number
- JPH0587595B2 JPH0587595B2 JP63104160A JP10416088A JPH0587595B2 JP H0587595 B2 JPH0587595 B2 JP H0587595B2 JP 63104160 A JP63104160 A JP 63104160A JP 10416088 A JP10416088 A JP 10416088A JP H0587595 B2 JPH0587595 B2 JP H0587595B2
- Authority
- JP
- Japan
- Prior art keywords
- electrolytic
- electrolytic bath
- cathode
- bath solution
- fluorination
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 150000002894 organic compounds Chemical class 0.000 claims description 29
- 238000003682 fluorination reaction Methods 0.000 claims description 25
- 238000000034 method Methods 0.000 claims description 15
- 239000000243 solution Substances 0.000 description 25
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 12
- -1 cyclic aliphatic primary amines Chemical class 0.000 description 11
- 239000007788 liquid Substances 0.000 description 10
- 238000005868 electrolysis reaction Methods 0.000 description 7
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 6
- 239000002253 acid Substances 0.000 description 6
- 150000001875 compounds Chemical class 0.000 description 6
- 229910052742 iron Inorganic materials 0.000 description 6
- 239000003792 electrolyte Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 150000001412 amines Chemical class 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 4
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 4
- IMFACGCPASFAPR-UHFFFAOYSA-N tributylamine Chemical compound CCCCN(CCCC)CCCC IMFACGCPASFAPR-UHFFFAOYSA-N 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- HQABUPZFAYXKJW-UHFFFAOYSA-N butan-1-amine Chemical compound CCCCN HQABUPZFAYXKJW-UHFFFAOYSA-N 0.000 description 2
- 150000001805 chlorine compounds Chemical class 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 150000002148 esters Chemical class 0.000 description 2
- 150000002222 fluorine compounds Chemical class 0.000 description 2
- 125000001153 fluoro group Chemical group F* 0.000 description 2
- 150000004820 halides Chemical class 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 150000004812 organic fluorine compounds Chemical class 0.000 description 2
- 238000010992 reflux Methods 0.000 description 2
- YFTHZRPMJXBUME-UHFFFAOYSA-N tripropylamine Chemical compound CCCN(CCC)CCC YFTHZRPMJXBUME-UHFFFAOYSA-N 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- NJBCRXCAPCODGX-UHFFFAOYSA-N 2-methyl-n-(2-methylpropyl)propan-1-amine Chemical compound CC(C)CNCC(C)C NJBCRXCAPCODGX-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910000792 Monel Inorganic materials 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 150000008065 acid anhydrides Chemical class 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 150000001299 aldehydes Chemical class 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- 150000001338 aliphatic hydrocarbons Chemical class 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 150000004982 aromatic amines Chemical class 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 150000008378 aryl ethers Chemical class 0.000 description 1
- 150000001721 carbon Chemical group 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 239000011203 carbon fibre reinforced carbon Substances 0.000 description 1
- 150000001735 carboxylic acids Chemical class 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000011437 continuous method Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 150000002506 iron compounds Chemical class 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- DIAIBWNEUYXDNL-UHFFFAOYSA-N n,n-dihexylhexan-1-amine Chemical compound CCCCCCN(CCCCCC)CCCCCC DIAIBWNEUYXDNL-UHFFFAOYSA-N 0.000 description 1
- VEBPYKMCKZTFPJ-UHFFFAOYSA-N n-butyl-n-propylbutan-1-amine Chemical compound CCCCN(CCC)CCCC VEBPYKMCKZTFPJ-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 229950008618 perfluamine Drugs 0.000 description 1
- RVZRBWKZFJCCIB-UHFFFAOYSA-N perfluorotributylamine Chemical compound FC(F)(F)C(F)(F)C(F)(F)C(F)(F)N(C(F)(F)C(F)(F)C(F)(F)C(F)(F)F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)F RVZRBWKZFJCCIB-UHFFFAOYSA-N 0.000 description 1
- JAJLKEVKNDUJBG-UHFFFAOYSA-N perfluorotripropylamine Chemical compound FC(F)(F)C(F)(F)C(F)(F)N(C(F)(F)C(F)(F)C(F)(F)F)C(F)(F)C(F)(F)C(F)(F)F JAJLKEVKNDUJBG-UHFFFAOYSA-N 0.000 description 1
- 150000002989 phenols Chemical class 0.000 description 1
- 229920000570 polyether Polymers 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 150000003335 secondary amines Chemical class 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
- 235000011121 sodium hydroxide Nutrition 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 150000003460 sulfonic acids Chemical class 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 150000003512 tertiary amines Chemical class 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- 125000005270 trialkylamine group Chemical group 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Landscapes
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Description
（産業上の利用分野）
本発明は、電解浴中の陽極及び陰極の間で電気
化学的に有機化合物をフツ素化する電解フツ素化
方法に関する。
（従来技術）
有機化合物を電気化学的にフツ素化する電解フ
ツ素化方法はよく知られている。例えば、特開昭
47−18775号公報には、有機化合物を含む電解浴
液を循環させながら、有機化合物のフツ素化を行
なうことが示されている。
（発明が解決しようとする問題点）
しかしながら、上記した方法では原料の有機化
合物に対応するパーフルオロ有機化合物の収率が
十分満足できるものではない。また、上記の方法
で長期にわたつて電解フツ素化を行なうと槽電圧
に次第に上昇し、ついには電解フツ素化を停止し
なければならない場合が生じることがわかつた。
〔課題を解決するための手段〕
本発明者らは、上記した問題点に鑑み、各種の
実験を繰返した結果、電解浴液の循環が、得られ
るパーフルオロ有機化合物の収率及び電解浴槽の
槽電圧に関係することを見い出した。そして、陽
極及び陰極で挾まれた空間に於ける電解浴液の滞
在時間が特定の範囲になるように電解浴液を循環
することによつて上記の問題を解決できることを
見い出した。
即ち、本発明は、電解浴中の陽極及び陰極の間
で有機化合物のフツ素化を行なう電解フツ素化方
法に於いて、陽極及び陰極で挟まれた空間に於け
る電解浴液の一循環当りの滞在時間が0.5〜25秒
となるように電解浴液を循環させることを特徴と
する電解フツ素化方法である。
本発明に於いて、フツ素化の対象となる有機化
合物は、炭素原子に直接結合した水素原を有する
か、又は炭素−炭素２重結合を有する有機化合物
が何ら制御されず使用し得る。例えば、これまで
電解フツ素化の対象として知られている脂肪族炭
化水素、芳香族炭化水素等の炭化水素類；直鎖若
しくは環状の脂肪族第一アミン、第二アミン若し
くは第三アミン、芳香族アミン等のアミン類；直
鎖若しくは環状の脂肪族エーテル、芳香族エーテ
ル、ポリエーテル等のエーテル類；直鎖若しくは
環状の脂肪族アルコール、芳香族アルコール等の
アルコール類；フエノール類；脂肪族カルボン
酸、芳香族カルボン酸等及びこれらから誘導され
るクロライド、酸フルオライド等の酸ハライド、
或いは酸無水物、エステル等のカルボン酸及びそ
の誘導体類；ケトン類；アルデヒド類；脂肪族ス
ルホン酸、芳香族スルホン酸及びこれらから誘導
される酸クロライド、酸フルオライド等の酸ハラ
イド、或いはエステル等のスルホン酸及びその誘
導体類；チオエーテル等の含硫黄化合物等を挙げ
ることができる。これらの中でも電解フツ素化で
用いるフツ化水素への溶解性性を勘案すると、分
子中に酸素原子又は窒素原を有する有機化合物が
好ましい。勿論、上記した有機化合物の水素原子
が一部フツ素原子で置換された有機化合物、例え
ば、水素原子とフツ素原子の数の比（Ｈ／Ｆ）が
１／２以上であるような一部フツ素化された有機
化合物も、本発明に於ける原料として用い得るこ
とは言うまでもない。
上記した有機化合物の中でも、本発明に於いて
特に槽電圧の上昇抑効果が顕著である化合物は、
炭素原子の数が４〜50個、さらには６〜25個、特
に10〜18個である有機化合物である。また、アミ
ン類、更にはトリアルキルアミン類を原料として
用いた場合には目的とするパーフルオロ有機化合
物が高収率で得られる。上記したアミン類として
は、トリプロピルアミン、トリブチルアミン、ト
リベンチルアミン、トリヘキシルアミン、ジペン
チルブチルアミン、ジブチルプロピルアミン等を
挙げることができる。
本発明の電解フツ素化では、上記の有機化合物
をフツ素水素に溶解又は分散させて通電される。
フツ素水素としては、市販されている無水フツ化
水素酸がそのまま、或いは必要に応じて微量含さ
れている水分を予め低電流密度での電解等の公知
の方法で除去した後に用いられる。
本発明い於いては、バツチ式及び連続式のいず
れの方法で電解フツ素化を行なつても良いが、特
に原料となる有機化合物とフツ化水素とをそれぞ
れ連続的に又は間欠的に電解浴液中に補給して、
電解浴液中における原料の有機化合物および中間
生成物である種々のフツ素化有機化合物の濃度お
よび組成をほぼ定常状態に維持しつつ、長期に連
続して反応を行なう連続式が好適である。この
時、これら有機化合物の合計の濃度が一般には２
〜40重量％、更には、３〜30重量％の範囲内にな
るように選択することが好ましい。
本発明の特徴は、電解浴液の循環に際して、陽
極及び陰極で挟まれた空間に於ける電解浴液の一
循環当りの滞在時間が0.5〜25秒、好ましくは１
〜20秒、さらに好ましくは３〜20秒となるように
維持する点にある。尚、陽極及び陰極で挟まれた
空間における電解浴液の一循環当りの滞在時間と
は、相対する一対の陽極及び陰極の両者に挟まれ
た空間を電解浴液が通過するのに要する時間と言
いかえることができる。電解浴液の一循環当りの
滞在時間が上記の範囲をはずれた場合には、原料
の有機化合物に対応した目的とするパーフルオロ
有機化合物の収率が低くなる。また、電解槽の電
圧が上昇し、長期の運転に耐えられない。因に、
前記した従来の技術における電解浴液の滞在時間
は、本発明者らの計算によると約240秒である。
本発明に於いては、電解フツ素化反応を均一に
行なうために、電極の形状と電解浴液の流れ方向
との関係を次のように選ぶことが好ましい。
電解浴液を電極面にほぼ平行に流れるように
循環する。
電解浴液の流れ方向に於ける陽極と陰極とで
挟まれた空間の長さがほぼ一定となるように電極
の形状を選択する。
電解浴液の流れ方向は上記のようであれば、
上下方向及び左右方向のいずれであつても良い。
上記及びを満足する場合を具体的に例示す
ると次のようである。例えば、第１図に示したよ
うに、長方形の陽極１及び陰極２を交互に配列し
た電極を使用し、電解浴液を該電極面にほぼ平行
に、且つ、該長方形の電極の短辺３又は長辺４の
いずれか一方に対して直角方向に流す方法が挙げ
られる。第１図中、矢印Ａは短辺３に、矢印Ｂは
長辺４に対して直角方向に電解浴液を流した場合
の電解浴液の流れ方向を示す。また、第２図に示
すように帯状の陽極１（又は陰極２）を蛇行しＵ
字型に配例し、陽極１（又は陰極２）によつて形
成された空間に陰極２（又は陽極１）を挿入した
電極を使用し、電解浴液を該電極面に平行に、且
つ、該帯状の電極の巾方向に流す方法等が挙げら
れる。第２図中、矢印は電解浴液の流れ方向を示
す。
このように電極の形状と電解浴液の流れ方向と
を選択した場合には、陽極及び陰極で挟まれた空
間に於ける電解浴液の一循環当りの滞在時間は、
次式で算出される。
ｔ＝／ｖ
但し、ｔ：滞在時間（秒）
ｖ：電解浴液の電極面に平行な方向の線
速度（cm／秒）
：電解浴液の流れ方向の電極の長さ
（cm）
上記の電解浴液の循環は、電解槽内でのみ行な
うこともできるが、一般には、電解浴液を電解槽
外に一担取り出し、それを再び電解槽内に供給す
る方法で循環を行なうことが好ましい。この時、
反応の進行に伴い生成し沈降してくるパーフルオ
ロ有機化合物を効率良く電解浴液から分離した
り、また安定に反応を行う為に、電解浴液の保持
量を大きくする等の目的で、通常、循環ライン中
に循環槽を設けることが好ましい。電解浴液の循
環の手段は、ポンプを用いる方法等の公知の方法
で行なうことができる。
本発明の電解フツ素化方法で使用される電極及
び電解槽は、公知のものが何ら制限されず使用し
得る。陽極としては、通常はニツケル又はその合
金が用いられ、陰極としては、ニツケル又はその
合金の他に鉄、ステンレススチール、銅等が用い
られる。また、電解槽は、上記した陰極の材質が
そのまま使用し得る他、フツ素樹脂も用いること
ができる。上記した陽極と陰極との極間距離は、
一般には0.5〜５mm程度とすることが好ましい。
なお、電解槽が工業的規模より小さく、例えば
電解浴液の流れ方向の電極の長さが50cm以下の場
合には、電解浴液の線速度が1.5cm／秒以上、好
ましくは2.0cm／秒以上、さらに好ましくは3.0
cm／秒以上であることが、長期間にわたつて安定
な電解を行なうために好適である。
電解の条件も公知の範囲から適宜選択すれば良
いが、通常は温度−15〜20℃、電流密度0.1〜
6A／ｄm2、槽電圧４〜9Vの範囲で採用される。
本発明に従えば、1.5A／ｄm2以上更には3A／ｄ
m2以上の比較的高い電流密度を採用した場合に特
に好ましい効果を得ることができる。
本発明に於いては、電解浴液と中の鉄の濃度を
1.5ppm以下、さらには0.45ppm以下とすること
が、安定に長期の電解フツ素化を行なうために好
適である。この場合の鉄の濃度とは、鉄イオン、
鉄化合物等に含まれる鉄原子の総量の電解浴液に
対する濃度である。
電解フツ素化反応において陰極で発生する水素
は、有機化合物の分解により発生した沸点の低い
低分子量の化合物と共に通常、電解槽の、場合に
よつては前述した循環槽の上部に設けられた還流
冷却器をとおして排出される。
このような電解フツ素化によつて有機化合物
は、フツ素化されて部分フツ素化有機化合物とな
る。さらにフツ素化されてパーフルオロ有機化合
物も得られる。パーフルオロ有機化合物は、電解
フツ素化に於ける電解浴液から層分離して沈降
し、分子中に少量の水素原子が残存した不完全フ
ツ素化物を含む混合物として通常、電解槽又は循
環槽の下部から得られる。
目的とするパーフルオロ有機化合物の沸点が低
い場合、電解槽から気体となつて排出されること
もあり、これを冷却して回収することもできる。
（効果〕
本発明の方法によると、原料である有機化合物
に対応したパーフルオロ有機化合物が高収率で得
られる。しかも、槽電圧の上昇がなく、長期にわ
たつて安定した電解フツ素化反応が可能である。
実施例 １
面積5.6dm2（巾8.0cm、高さ70cm）、厚さ２mmの
一対のニツケル製陰陽極が２mmの間隔で配置され
ているモネル製の電解槽を用いてトリブチルアミ
ンの電解フツ素化を行つた。まず、モネル製の循
環槽（容量８）に５の水不含のフツ化水素と
トリブチルアミンをトリブチルアミンの濃度が８
重量％となるように供給した。この混合液をポン
プにより種々の速度で電解槽の下部より電極間に
流し、電極上部よりオーバーフローで再び循環槽
にもどしながら電解を開始した。徐々に電流値を
上げてゆき、40時間後より19.6A（電流密度
3.5A／ｄm2）で定電流電解を行つた。この時、
電解槽および循環槽を外部から冷却して、電解浴
液の温度を約０℃に保つた。
電解フツ素化によつて発生する水素ガスは電解
槽の上部に設けられた−35℃の還流冷却器をとお
して排出した。反応中電解浴液の量を一定に保つ
ようにフツ化水素を連続的に補給した。電解開始
後、まもなくトリブチルアミンの循環槽への供給
を開始し、電解浴液中における全アミンの濃度が
約15重量％の定常状態を維持するようにした。生
成するパーフルオロ化合物を循環槽の下部より間
欠的に抜き出した。これを40重量％のカセセイソ
ーダ水溶液とジイソブチルアミンの等容量混合物
中で120時間リフラツクスして脱フツ化水素し、
水洗後蒸留を行うことによりパーフルオロトリブ
チルアミンを得た。
電解浴液の電極間の滞在時間が20、10、５、１
秒で電解フツ素化を行つた場合の定常状態におけ
る電圧、収率等を、滞在時間が50、0.4秒の場合
（比較例）と比較して、表１に示した。
尚、電解浴液中の鉄の濃度は、いずれの場合も
0.3ppm以下であつた。
(Industrial Application Field) The present invention relates to an electrolytic fluorination method for electrochemically fluorinating an organic compound between an anode and a cathode in an electrolytic bath. (Prior Art) Electrolytic fluorination methods for electrochemically fluorinating organic compounds are well known. For example, Tokukai Akira
No. 47-18775 discloses that fluorination of organic compounds is carried out while circulating an electrolytic bath solution containing the organic compounds. (Problems to be Solved by the Invention) However, in the above-described method, the yield of the perfluoroorganic compound corresponding to the raw material organic compound is not sufficiently satisfactory. Furthermore, it has been found that when electrolytic fluorination is carried out for a long period of time using the above method, the cell voltage gradually increases, and there are cases in which the electrolytic fluorination has to be stopped. [Means for Solving the Problems] In view of the above-mentioned problems, the present inventors have repeatedly conducted various experiments and found that circulation of the electrolytic bath solution improves the yield of perfluorinated organic compounds obtained and the electrolytic bath. We found that it is related to the cell voltage. The inventors have also discovered that the above problem can be solved by circulating the electrolytic bath solution such that the electrolytic bath solution stays in the space between the anode and the cathode within a specific range. That is, the present invention provides an electrolytic fluorination method in which an organic compound is fluorinated between an anode and a cathode in an electrolytic bath. This is an electrolytic fluorination method characterized by circulating an electrolytic bath solution so that the residence time per cycle is 0.5 to 25 seconds. In the present invention, the organic compound to be fluorinated has a hydrogen atom directly bonded to a carbon atom, or an organic compound having a carbon-carbon double bond can be used without any control. For example, hydrocarbons such as aliphatic hydrocarbons and aromatic hydrocarbons that have been known as targets for electrolytic fluorination; linear or cyclic aliphatic primary amines, secondary amines, or tertiary amines, aromatic Amines such as group amines; Ethers such as linear or cyclic aliphatic ethers, aromatic ethers, and polyethers; Alcohols such as linear or cyclic aliphatic alcohols and aromatic alcohols; Phenols; Aliphatic carbons acids, aromatic carboxylic acids, etc., and acid halides such as chlorides and acid fluorides derived from these;
Or carboxylic acids and their derivatives such as acid anhydrides and esters; ketones; aldehydes; aliphatic sulfonic acids, aromatic sulfonic acids and acid halides such as acid chlorides and acid fluorides derived therefrom, or esters. Examples include sulfonic acids and derivatives thereof; sulfur-containing compounds such as thioethers. Among these, in consideration of solubility in hydrogen fluoride used in electrolytic fluorination, organic compounds having an oxygen atom or a nitrogen source in the molecule are preferred. Of course, organic compounds in which some of the hydrogen atoms of the above-mentioned organic compounds are replaced with fluorine atoms, for example, some in which the ratio of the number of hydrogen atoms to fluorine atoms (H/F) is 1/2 or more It goes without saying that fluorinated organic compounds can also be used as raw materials in the present invention. Among the above-mentioned organic compounds, compounds that have a particularly remarkable effect of suppressing the increase in cell voltage in the present invention are:
It is an organic compound having 4 to 50, even 6 to 25, especially 10 to 18 carbon atoms. In addition, when amines, or even trialkylamines, are used as raw materials, the desired perfluoroorganic compound can be obtained in high yield. Examples of the above-mentioned amines include tripropylamine, tributylamine, tribentylamine, trihexylamine, dipentylbutylamine, dibutylpropylamine, and the like. In the electrolytic fluorination of the present invention, the above-mentioned organic compound is dissolved or dispersed in fluorine-hydrogen and then energized.
As the fluorine-hydrogen, commercially available anhydrous hydrofluoric acid is used as it is, or if necessary, after a trace amount of water contained therein has been previously removed by a known method such as electrolysis at a low current density. In the present invention, electrolytic fluorination may be carried out by either a batch method or a continuous method, but in particular, the raw organic compound and hydrogen fluoride may be electrolyzed continuously or intermittently, respectively. Replenish it into the bath liquid,
A continuous system is preferred, in which the reaction is carried out continuously over a long period of time while maintaining the concentration and composition of the raw organic compound and the various intermediate products, fluorinated organic compounds, in the electrolytic bath liquid at a substantially steady state. At this time, the total concentration of these organic compounds is generally 2
It is preferable to select it within the range of ~40% by weight, more preferably 3~30% by weight. A feature of the present invention is that during circulation of the electrolytic bath solution, the residence time of the electrolytic bath solution per circulation in the space between the anode and the cathode is 0.5 to 25 seconds, preferably 1 second.
20 seconds, more preferably 3 to 20 seconds. The residence time per circulation of the electrolytic bath in the space between the anode and the cathode is the time required for the electrolytic bath to pass through the space between the opposing anode and cathode. I can rephrase that. If the residence time per circulation of the electrolytic bath solution is out of the above range, the yield of the target perfluorinated organic compound corresponding to the raw material organic compound will be low. Additionally, the voltage of the electrolytic cell increases, making it unsustainable for long-term operation. Incidentally,
According to calculations made by the present inventors, the residence time of the electrolytic bath solution in the conventional technique described above is approximately 240 seconds. In the present invention, in order to perform the electrolytic fluorination reaction uniformly, it is preferable to select the relationship between the shape of the electrode and the flow direction of the electrolytic bath solution as follows. The electrolytic bath solution is circulated so that it flows approximately parallel to the electrode surface. The shape of the electrodes is selected so that the length of the space between the anode and the cathode in the flow direction of the electrolyte bath is approximately constant. If the flow direction of the electrolytic bath liquid is as shown above,
It may be in either the vertical direction or the horizontal direction. A specific example of a case that satisfies the above conditions is as follows. For example, as shown in FIG. 1, an electrode in which rectangular anodes 1 and cathodes 2 are arranged alternately is used, and the electrolytic bath liquid is applied almost parallel to the electrode surface and on the short side 3 of the rectangular electrode. Alternatively, a method of flowing in a direction perpendicular to one of the long sides 4 can be mentioned. In FIG. 1, arrow A indicates the flow direction of the electrolytic bath solution when the electrolytic bath solution flows in the direction perpendicular to the short side 3 and the arrow B indicates the direction perpendicular to the long side 4. In addition, as shown in Fig. 2, the belt-shaped anode 1 (or cathode 2) is meandered and U
Using an electrode arranged in the shape of a letter, with the cathode 2 (or anode 1) inserted into the space formed by the anode 1 (or cathode 2), the electrolytic bath liquid is applied parallel to the electrode surface, and Examples include a method of flowing in the width direction of the strip-shaped electrode. In FIG. 2, arrows indicate the direction of flow of the electrolyte bath. When the shape of the electrode and the flow direction of the electrolytic bath liquid are selected in this way, the residence time of the electrolytic bath liquid per circulation in the space between the anode and the cathode is:
It is calculated using the following formula. t=/v However, t: Residence time (seconds) v: Linear velocity of the electrolyte bath in the direction parallel to the electrode surface (cm/second): Length of the electrode in the flow direction of the electrolyte bath (cm) Although the electrolytic bath solution can be circulated only within the electrolytic cell, it is generally preferable to carry out the circulation by taking out a portion of the electrolytic bath liquid outside the electrolytic cell and supplying it again into the electrolytic cell. . At this time,
It is usually used for the purpose of efficiently separating perfluorinated organic compounds that are generated and precipitated as the reaction progresses from the electrolytic bath solution, and to increase the amount of electrolytic bath solution retained in order to perform the reaction stably. It is preferable to provide a circulation tank in the circulation line. The electrolytic bath solution can be circulated by a known method such as using a pump. The electrodes and electrolytic cell used in the electrolytic fluorination method of the present invention may be any known ones without any restriction. As the anode, nickel or its alloy is usually used, and as the cathode, in addition to nickel or its alloy, iron, stainless steel, copper, etc. are used. Furthermore, in addition to the above-mentioned cathode materials that can be used as they are for the electrolytic cell, fluororesins can also be used. The distance between the anode and cathode mentioned above is
Generally, it is preferable to set it to about 0.5 to 5 mm. In addition, when the electrolytic cell is smaller than industrial scale, for example, the length of the electrode in the flow direction of the electrolytic bath liquid is 50 cm or less, the linear velocity of the electrolytic bath liquid is 1.5 cm/sec or more, preferably 2.0 cm/sec. or higher, preferably 3.0
cm/sec or more is suitable for performing stable electrolysis over a long period of time. Electrolysis conditions may be selected appropriately from known ranges, but usually the temperature is -15 to 20°C and the current density is 0.1 to 20°C.
It is used in a range of 6A/dm 2 and a cell voltage of 4 to 9V.
According to the present invention, 1.5A/dm 2 or more, and even 3A/dm
Particularly favorable effects can be obtained when a relatively high current density of m 2 or more is employed. In the present invention, the concentration of iron in the electrolytic bath solution is
A concentration of 1.5 ppm or less, more preferably 0.45 ppm or less, is suitable for stable long-term electrolytic fluorination. In this case, the concentration of iron is iron ion,
This is the concentration of the total amount of iron atoms contained in iron compounds, etc., relative to the electrolytic bath solution. Hydrogen generated at the cathode in the electrolytic fluorination reaction, along with low-molecular-weight compounds with low boiling points generated by decomposition of organic compounds, is usually collected in a reflux tank installed at the top of the electrolytic cell, or in some cases, the above-mentioned circulation tank. It is discharged through a cooler. By such electrolytic fluorination, the organic compound is fluorinated to become a partially fluorinated organic compound. Furthermore, perfluorinated organic compounds can be obtained by fluorination. Perfluorinated organic compounds are separated into layers and precipitated from the electrolytic bath solution during electrolytic fluorination, and are usually stored in an electrolytic cell or circulation tank as a mixture containing incompletely fluorinated compounds with a small amount of hydrogen atoms remaining in the molecule. obtained from the bottom of. If the target perfluoroorganic compound has a low boiling point, it may be discharged from the electrolytic cell as a gas, which can be cooled and recovered. (Effects) According to the method of the present invention, a perfluorinated organic compound corresponding to the raw material organic compound can be obtained in high yield.Moreover, there is no increase in cell voltage, and the electrolytic fluorination reaction is stable over a long period of time. Example 1 A Monel electrolytic cell with an area of 5.6 dm 2 (width 8.0 cm, height 70 cm) and a pair of nickel anodes with a thickness of 2 mm arranged at a spacing of 2 mm was used. Electrolytic fluorination of butylamine was carried out.First, 5 parts of water-free hydrogen fluoride and tributylamine were placed in a Monel circulation tank (capacity 8) until the concentration of tributylamine was 8.
% by weight. This mixed solution was pumped between the electrodes from the bottom of the electrolytic cell at various speeds, and electrolysis was started while overflowing from the top of the electrodes and returning it to the circulation tank. Gradually increase the current value to 19.6A (current density) after 40 hours.
Constant current electrolysis was performed at 3.5 A/dm 2 ). At this time,
The electrolytic bath and circulation bath were externally cooled to maintain the temperature of the electrolytic bath at about 0°C. Hydrogen gas generated by electrolytic fluorination was discharged through a -35°C reflux condenser installed at the top of the electrolytic cell. During the reaction, hydrogen fluoride was continuously replenished so as to keep the amount of the electrolytic bath solution constant. Immediately after the start of electrolysis, supply of tributylamine to the circulation tank was started so that the concentration of all amines in the electrolytic bath solution was maintained at a steady state of about 15% by weight. The generated perfluoro compound was intermittently extracted from the bottom of the circulation tank. This was refluxed for 120 hours in an equal volume mixture of 40% by weight caustic soda aqueous solution and diisobutylamine to dehydrofluoride.
After washing with water, distillation was performed to obtain perfluorotributylamine. Residence time of electrolytic bath solution between electrodes is 20, 10, 5, 1
Table 1 shows the voltage, yield, etc. in a steady state when electrolytic fluorination is performed in seconds, compared with the case where residence time is 50 seconds and 0.4 seconds (comparative example). In addition, the concentration of iron in the electrolytic bath solution is
It was below 0.3ppm.
【表】
＊ 定常状態における平均値である。
＊＊ No.５及びNo.６はこの時点で電解を停止した。
実施例 ２
電解浴液中の鉄分を0.2ppm以下に調し、且つ
滞在時間を７秒に設定した以外は実施例１と同様
にしてトリプロピルアミンの電解フツ素化を行な
つた。パーフルオロトリプロピルアミンの収率は
42.5％であり、4000時間経過後も槽電圧の上昇は
なく、安定した運転が可能であつた。[Table] * Average value in steady state.
** No. 5 and No. 6 stopped electrolysis at this point.
Example 2 Electrolytic fluorination of tripropylamine was carried out in the same manner as in Example 1, except that the iron content in the electrolytic bath solution was adjusted to 0.2 ppm or less and the residence time was set to 7 seconds. The yield of perfluorotripropylamine is
42.5%, and there was no increase in cell voltage even after 4000 hours, and stable operation was possible.
第１図及び第２図は、電極の形状と電解浴液の
流れ方向との関係を示す図である。
図中、１は陽極、２は陰極、３は短辺、４は長
辺を夫々示す。
FIGS. 1 and 2 are diagrams showing the relationship between the shape of the electrode and the flow direction of the electrolyte bath. In the figure, 1 indicates an anode, 2 a cathode, 3 a short side, and 4 a long side.
Claims (1)
フツ素化を行なう電解フツ素化方法に於いて、陽
極及び陰極で挟まれた空間に於ける電解浴液の一
循環当りの滞在時間が0.5〜25秒となるように電
解浴液を循環させることを特徴とする電解フツ素
化方法。1. In an electrolytic fluorination method in which organic compounds are fluorinated between an anode and a cathode in an electrolytic bath, the residence time of the electrolytic bath solution per circulation in the space between the anode and the cathode is An electrolytic fluorination method characterized by circulating an electrolytic bath solution for 0.5 to 25 seconds.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63104160A JPH0230785A (en) | 1988-04-20 | 1988-04-28 | Method for electrolytic fluorination |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63-95630 | 1988-04-20 | ||
| JP9563088 | 1988-04-20 | ||
| JP63104160A JPH0230785A (en) | 1988-04-20 | 1988-04-28 | Method for electrolytic fluorination |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0230785A JPH0230785A (en) | 1990-02-01 |
| JPH0587595B2 true JPH0587595B2 (en) | 1993-12-17 |
Family
ID=26436854
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63104160A Granted JPH0230785A (en) | 1988-04-20 | 1988-04-28 | Method for electrolytic fluorination |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0230785A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5322597A (en) * | 1992-07-30 | 1994-06-21 | Minnesota Mining And Manufacturing Company | Bipolar flow cell and process for electrochemical fluorination |
| US6361678B1 (en) | 2000-08-22 | 2002-03-26 | 3M Innovative Properties Company | Method of detecting a short incident during electrochemical processing and a system therefor |
| US6919015B2 (en) | 2002-12-16 | 2005-07-19 | 3M Innovative Properties Company | Process for manufacturing fluoroolefins |
| CN112226783B (en) * | 2020-10-27 | 2022-03-08 | 浙江诺亚氟化工有限公司 | Electrochemical combined fluorination process |
-
1988
- 1988-04-28 JP JP63104160A patent/JPH0230785A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0230785A (en) | 1990-02-01 |
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