Jī-têng kiat-ha̍p

Nâ-sek ōe-chhut jī-têng kiat-ha̍p: acetaldehyde, acetone, methyl acetate (téng-chōa, ùi tò-chhiú kàu chiàⁿ-chhiú-pêng), kah 3-oxazoline, acetone ê oxime, and propene (ē-chōa)

Jī-têng kiat-ha̍p (Hàn-jī: 二重結合; Eng-gí: double bond) sī 1 chióng kiōng-iú kiat-ha̍p, 2 ê goân-chú chi-kan hun-hiáng 4 ê kiat-ha̍p tiān-chú. Tī kiat-kò͘-sek tiong, jī-têng kiat-ha̍p ê Kì-hō sī 2 tiâu pêng-hêng-sòaⁿ (=).

Jī-têng kiat-ha̍p pí toaⁿ-kiat-ha̍p koh-khah kiông, iā koh-khah té. In ê kiat-ha̍p kip-sò͘ sī 2.

Siōng chia̍p-khòaⁿ ê jī-têng kiat-ha̍p sī 2 ê thòaⁿ-sò͘ goân-chú chi-kan, mā chhut-hiān tī alkene chi-tiong.

Goân-lí

Jī-têng kiat-ha̍p ê hêng-sêng, ē-sái iōng hūn-sêng kúi-he̍k lâi thiah-bêng. Tī ethene lāi-té, ta̍k ê thòaⁿ-sò͘ goân-chú ū 3 ê sp² kúi-he̍k chham 1 ê p kúi-he̍k. 3 ê sp² kúi-he̍k tiàm kâng 1 ê pêⁿ-bīn, hō͘-siong lóng gia̍p 120° ê kak-tō͘. p kúi-he̍k siong-tùi chit ê péng-bīn sī khiā-ti̍t--ê. Thòaⁿ-sò͘ goân-chú chiap-kīn ê sî, 2 ê sp² kúi-he̍k sio-tha̍h, hêng-sêng σ kiat-ha̍p. Siâng-sî, 2 ê p kúi-he̍k sio chiap-kīn, hêng-sêng π kiat-ha̍p. Nā-sī beh chīn-liōng sio-tha̍h, π kúi-he̍k tio̍h-ài pêng-hêng, só͘-í hūn-chú bé-sái tńg-se̍h; chit-hō te̍k-sek sán-seng cis trans ī-kò͘.

2 ê sp2 kui-ê sio-óa, hêng-sêng sp2-sp2 ê σ kiat-ha̍p.		2 ê p kúi-he̍k sio-tha̍h, tī kah σ kiat-ha̍p pêng-hêng ê pêⁿ-bīn téng-koân hêng-sêng π kiat-ha̍p.