東莞英凱教育(環(huán)球雅思分校)
ALevel化學(xué)烯烴方面的知識(shí)點(diǎn)
- 2025年4月26日
- 文章來自: dgukedu
- 分類: alevel備考
ALevel考試科目眾多,包括數(shù)理化這些常見的科目,特別是ALevel化學(xué)的部分,需要記憶的公式非常多,為了幫助大家更好的備考ALevel,下面我們就來講講烯烴方面的知識(shí)點(diǎn),一起來學(xué)習(xí)一下吧!
烯烴通過加成反應(yīng)可以生成許多高分子材料。例如,CH2=CH2可以生成聚乙烯,CH3CH=CH2可以生成聚丙烯,CH2=CHCl可以生成聚氯乙烯,CF2=CF2可以生成聚四氟乙烯。
The homologous series of alkenes has the general formula CnH2n. Alkenes are unsaturated hydrocarbons with one carbon-carbon double bond consisting of a σbond and a πbond.
烯烴同系物通式為:CnH2n。烯烴是具有一個(gè)碳碳雙鍵的不飽和碳?xì)浠衔?,碳碳雙鍵由一個(gè)σ鍵和一個(gè) π鍵組成。
Ethene is a planar molecule, other alkenes are planar of the double bond and the four adjacent atom. Many alkenes have cis-trans isomers which arise because rotation about the double bond is prevented.
乙烯是一個(gè)平面分子。烯烴的碳碳雙鍵以及與其相連的四個(gè)原子均處在同一平面上,由于碳碳雙鍵不可扭轉(zhuǎn),一些烯烴存在順反異構(gòu)體。
Alkenes are more reactive than alkanes because they contain aπbond. The characteristic reaction of the alkene functional group is addition, which occurs across the πbond. For example ethene produces ethane with hydrogen over a nickel catalyst; 1,2-dibromoethane with bromine at room temperature; chloroethane with hydrogen chloride at room temperature; ethanol with steam in the prescence of H3PO4.
>由于烯烴中存在一個(gè)π鍵,烯烴相對(duì)于烷烴來說較活潑。由于碳碳雙鍵官能團(tuán)的存在,烯烴可以通過π鍵發(fā)生加成反應(yīng)。例如,乙烯和氫氣在鎳的催化作用下可以生成乙烷,在室溫下可以與溴反應(yīng)生成1.2-二溴乙烷,在室溫下雨氯化氫反應(yīng)生成氯乙烷,在H3PO4存在的條件下與水蒸汽生成乙醇。
The mechanism of the reaction of bromine with ethene is electrophilic addition. Electrophiles accept a pair of electrons from an electron-rich atom or centre, in this case theπbond. A carbocation intermediate is formed after the addition of the first bromine atom. This rapidly reacts with a bromide ion to form 1,2-dibromoethane
乙烯與溴的反應(yīng)機(jī)理為親電加成.溴受外界影響,其一端帶微正電荷,形成親電試劑,親電試劑容易與富電子原子結(jié)合,形成π配位化合物,雙鍵中的碳在接受了第一個(gè)溴原子的進(jìn)攻之后,形成了碳正離子,碳正離子的形成促使其很快與另一個(gè)溴原子結(jié)合,形成1.2-二溴乙烷。
Alkenes produce many useful polymers by addition polymerisation. For example, poly(ethene) from CH2=CH2, poly(propene) from CH3CH=CH2, poly(chloroethene) from CH2=CHCl and poly(tetrafluoroethene) from CF2=CF2.
烯烴通過加成反應(yīng)可以生成許多高分子材料。例如,CH2=CH2可以生成聚乙烯,CH3CH=CH2可以生成聚丙烯,CH2=CHCl可以生成聚氯乙烯,CF2=CF2可以生成聚四氟乙烯。
The disposal of polymers is difficult as they are chemically inert and non-biodegradable. When burnt, they may produce toxic products such as hydrogen chloride from PVC(poly(chloroethene)). Whilst much manufacturing wast plastic is recycled, the costs of collecting and sorting most domestic plastic are too high to make recycling worthwhile. Use of the energy released on combustion (for heating buildings) is a better option for domestic waste, but treatment of flue gases is required to remove toxic pollutants. A third option is feedstock recycling where the polymers are separated and used as feedstock to make new polymers.
因?yàn)楦叻肿硬牧蠈儆诨瘜W(xué)惰性物質(zhì),并且不能夠生物降解,因此,對(duì)于高分子物質(zhì)的處理相對(duì)困難。如聚氯乙烯在焚燒情況下可以產(chǎn)生氯化氫有毒氣體。
一般有以下幾種方法:
第一,一些工業(yè)廢舊塑料可以回收利用,但是其回收利用的造價(jià)是相當(dāng)高的;
第二,利用一些本土廢舊物的燃燒能量來給建筑物供熱,但對(duì)其煙道氣中的毒氣要做有效處理;
第三,將一些高分子廢棄物分類,作為新的高分子材料給料使用。
關(guān)于ALevel化學(xué)中烯烴的知識(shí)點(diǎn)就介紹到這里了,希望大家一定要重視起來,同時(shí)小編建議大家要關(guān)注真題的練習(xí),掌握基礎(chǔ)才能提升成績,如果還想了解更多關(guān)于自學(xué)alevel成績、a水準(zhǔn)考試要求的內(nèi)容,可以添加我們的客服微信kewo11。