公开(公告)号：US5162085A

公开(公告)日：1992-11-10

申请号：US482530

申请日：1990-02-21

申请人： Charles Cane ,  David A. Duncan ,  Sean P. O'Connor

发明人： Charles Cane ,  David A. Duncan ,  Sean P. O'Connor

IPC分类号： C07G99/00 ,  C10M125/00 ,  C10M125/06 ,  C10M125/10 ,  C10M129/08 ,  C10M129/10 ,  C10M129/16 ,  C10M129/40 ,  C10M129/42 ,  C10M129/93 ,  C10M135/30 ,  C10M159/22 ,  C10N10/04 ,  C10N20/00 ,  C10N20/02 ,  C10N30/04 ,  C10N70/00

CPC分类号： C07G17/008 ,  C10M159/22

摘要： A process for the preparation of lubricating oil additive concentrate having a TBN greater than 300 comprises reacting at elevated temperaturecomponent (A) at least one compound which is A(i) an alkaline earth metal hydrocarbyl-substituted phenate, A(ii) a hydrocarbyl-substituted phenol, A(iii) an alkaline earth metal hydrocarbyl-substituted phenate and a source of sulphur, A(iv) a hydrocarbyl-substituted phenol and a source of sulphur, A(v) an alkaline earth metal sulphurized hydrocarbyl-substituted phenate or A(vi) a sulphurized hydrocarbyl-substituted phenol.component (B) an alkaline earth metal basecomponent (C) a defined oxygenated compoundcomponent (D) a lubricating oil,component (E) carbon dioxidecomponent (F) sufficient to provide from 2 to 40% by weight based on the weight of the concentrate, of a defined carboxylic acid or derivative thereof, andcomponent (G) an ammonium alkanoate or a mono-, di-, tri- or tetra-alkyl ammonium formate or alkanoate,the weight ratios of components (A) to (G) being such as to produce a concentrate having a TBN greater than 300.

公开(公告)号：US5281345A

公开(公告)日：1994-01-25

申请号：US556823

申请日：1990-07-23

申请人： John Crawford ,  Sean P. O'Connor ,  Charles Cane

发明人： John Crawford ,  Sean P. O'Connor ,  Charles Cane

IPC分类号： C10M125/06 ,  C10M125/10 ,  C10M129/08 ,  C10M129/10 ,  C10M129/26 ,  C10M131/04 ,  C10M159/20 ,  C10M159/22 ,  C10M159/24 ,  C10M177/00 ,  C10N10/04 ,  C10N30/04 ,  C10N40/25 ,  C10N70/00 ,  C10M159/02

CPC分类号： C10M159/20 ,  C10M159/22 ,  C10M159/24

摘要： A process for the production of a lubricating oil additive concentrate comprises reacting at elevated temperature the following components:component (A) a defined acidcomponent (B)--a calcium base added either in a single addition or in a plurality of additions at intermediate points during the reaction,component (C)--at least one compound which is (i) water, (ii) a polyhydric alcohol having 2 to 4 carbon atoms, (iii) a di- (C.sub.3 or C.sub.4) glycol, (iv) a tri-(C.sub.2 -C.sub.4) glycol, (v) a mono- or poly-alkylene glycol alkyl ether of the formula (I)R(OR.sup.1).sub.x OR.sup.2 (I) wherein R is a C.sub.1 to C.sub.6 alkyl group, R.sup.1 is an alkylene group, R.sup.2 is hydrogen or a C.sub.1 to C.sub.6 alkyl group and x is an integer from 1 to 6, (vi) a C.sub.1 to C.sub.20 monohydric alcohol, (vii) a C.sub.1 to C.sub.20 ketone, (viii) a C.sub.1 to C.sub.10 carboxylic acid ester, or (ix) a C.sub.1 to C.sub.20 ether, optionally,component (D)--a lubricating oil,component (E)--carbon dioxide added subsequent to the, or each, addition of component (B), andcomponent (F)--a compound of formula IIR.sup.3 X (II) wherein X is a halogen and R.sup.3 is an alkyl, alkenyl or alkaryl group or halo derivative thereof.

摘要翻译： 用于生产润滑油添加剂浓缩物的方法包括在升高的温度下使以下组分反应：组分（A）所定义的酸组分（B） - 在中间点以单次添加或多次添加的钙碱 在反应期间，组分（C） - 至少一种化合物，其为（i）水，（ii）具有2至4个碳原子的多元醇，（iii）二（C3或C4）二醇，（iv） 三（C 2 -C 4）二醇，（v）式（I）R（OR 1）x OR 2（I）的单 - 或聚 - 亚烷基二醇烷基醚，其中R是C1至C6烷基，R1是亚烷基 基团，R 2是氢或C 1至C 6烷基，x是1至6的整数，（vi）C 1至C 20一元醇，（vii）C 1至C 20酮，（viii）C 1至C 10羧酸 酯，或（ix）C1至C20醚，任选的组分（D） - 在组分（B）添加或每次加入组分（B）和组分（F）后加入的润滑油，组分（E） - 二氧化碳， - 式I化合物 I R3X​​（II）其中X是卤素，R3是烷基，烯基或烷芳基或其卤代衍生物。

公开(公告)号：US5441652A

公开(公告)日：1995-08-15

申请号：US158143

申请日：1993-11-24

申请人： Sean P. O'Connor ,  Charles Cane

发明人： Sean P. O'Connor ,  Charles Cane

IPC分类号： C10M159/20 ,  C07G99/00 ,  C10M125/00 ,  C10M125/10 ,  C10M125/14 ,  C10M125/18 ,  C10M129/04 ,  C10M129/16 ,  C10M129/38 ,  C10M129/70 ,  C10M159/22 ,  C10M177/00 ,  C10N10/04 ,  C10N20/02 ,  C10N40/25 ,  C10N70/00

CPC分类号： C07G17/002 ,  C10M159/22

摘要： A process for the production of a lubricating oil additive concentrate having a TBN greater than 300 which process comprises reactingcomponent (A) a defined derivative of phenolcomponent (B) an alkaline earth metal base added either in a single addition of in a plurality of additions at intermediate points during the reaction,component (C) at least one compound which is (i) water, (ii) a C.sub.1 to C.sub.10 monohydric alcohol, (iii) a C.sub.1 to C.sub.20 ketone, (iv) a C.sub.1 to C.sub.10 carboxylic acid ester or (v) a C.sub.1 to C.sub.20 ether,component (D) a lubricating oil,component (E) carbon dioxide added subsequent to the, or each, addition of component (B),component (F) a defined carboxylic acid or derivativecomponent (G) at least one compound which is (i) an inorganic halide or (ii) an ammonium alkanoate or a mono-, di-, tri, or tetra-alkyl ammonium formate or alkanoate provided that, when component (G) is (ii), component (F) is not an acid chloride,the weight ratios of all components being such as to produce a concentrate having a TBN greater than 300.

摘要翻译： 一种生产TBN大于300的润滑油添加剂浓缩物的方法，该方法包括将组分（A）定义为苯酚组分（B）的衍生物，碱金属碱添加在多个 在反应中的中间点添加，组分（C）至少一种化合物，其为（i）水，（ii）C1至C10一元醇，（iii）C1至C20酮，（iv）C1至C10羧酸 酸性酯或（v）C1至C20醚，组分（D）润滑油，组分（E）二氧化碳，在组分（B），组分（F）中加入或每次加入所定义的羧酸或 衍生物组分（G）至少一种化合物，其为（i）无机卤化物或（ii）烷基铵或单 - ，二 - ，三 - 或四 - 烷基铵甲酸铵或链烷酸酯，条件是当组分（G） 是（ⅱ）中，组分（F）不是酰氯，所有组分的重量比都要生成 TBN大于300的浓缩物。

公开(公告)号：US5397484A

公开(公告)日：1995-03-14

申请号：US76384

申请日：1993-06-14

申请人： Charles Cane ,  Stephen J. Cook ,  Sean P. O'Connor

发明人： Charles Cane ,  Stephen J. Cook ,  Sean P. O'Connor

IPC分类号： C10M159/22 ,  C10N10/04 ,  C10N30/06 ,  C10N30/12 ,  C10N40/25 ,  C10N70/00

CPC分类号： C10M159/22

摘要： An additive concentrate composition having a TBN greater than 300 suitable for incorporation into a finished lubricating oil composition comprising:(I') a first alkaline earth metal sulphurised hydrocarbyl phenate, and(II') a lubricating oil,the first alkaline earth metal sulphurised hydrocarbyl phenate (I') being obtained by overbasing a second alkaline earth metal sulphurised hydrocarbyl phenate containing at least 4% by weight sulphur, or its precursors, in the presence of the lubricating oil (II'), the amount of the lubricating oil (II') being such that the ratio of the weight of the additive concentrate to the weight of the second alkaline earth metal sulphurised hydrocarbyl phenate, or its precursors, is at least 3.0.

摘要翻译： 一种TBN大于300的添加剂浓缩物组合物，其适用于掺入成品润滑油组合物中，该组合物包含：（I'）第一碱土金属硫化烃基酚盐和（II'）润滑油，第一碱土金属硫化烃基 酚酸盐（I'）是通过在润滑油（II'）存在下使含有至少4重量％硫或其前体的第二碱土金属硫化烃基酚盐过碱化得到的，润滑油（II '）使得添加剂浓缩物的重量与第二碱土金属硫化烃基酚盐或其前体的重量之比至少为3.0。

公开(公告)号：US5433871A

公开(公告)日：1995-07-18

申请号：US157336

申请日：1993-11-23

申请人： Sean P. O'Connor ,  John Crawford ,  Charles Cane

发明人： Sean P. O'Connor ,  John Crawford ,  Charles Cane

IPC分类号： C10M125/00 ,  C10M125/10 ,  C10M125/14 ,  C10M125/18 ,  C10M129/08 ,  C10M129/10 ,  C10M129/16 ,  C10M129/38 ,  C10M129/54 ,  C10M129/70 ,  C10M135/10 ,  C10M159/20 ,  C10M159/22 ,  C10M159/24 ,  C10M177/00 ,  C10N10/04 ,  C10N20/02 ,  C10N40/25 ,  C10N70/00

CPC分类号： C10M159/24 ,  C10M159/20 ,  C10M159/22 ,  C10M2201/082 ,  C10M2201/10 ,  C10M2207/021 ,  C10M2207/022 ,  C10M2207/04 ,  C10M2207/046 ,  C10M2207/08 ,  C10M2207/122 ,  C10M2207/126 ,  C10M2207/281 ,  C10M2209/108 ,  C10N2210/02 ,  C10N2230/04 ,  C10N2230/52 ,  C10N2270/02

摘要： A process for the production of a lubricating oil additive concentrate having a TBN greater than 300 which process comprises reacting at elevated temperaturecomponent (A) a defined mixture selected from defined sulphurized or non-sulphurized acids or calcium salts thereof,component (B) an alkaline earth metal base added either in a single addition or in a plurality of additions at intermediate points during the reaction,component (C) at least one compound which is (i) water, (ii) a polyhydric alcohol having 2 to 4 carbon atoms, (iii) a di- (C.sub.3 or C.sub.4) glycol, (iv) a tri-(C.sub.2 -C.sub.4) glycol, (v) a mono- or poly-alkylene glycol alkyl ether of the formula (I)R(OR.sup.1).sub.x OR.sup.2 (I)wherein R is a C.sub.1 to C.sub.6 alkyl group, R.sup.1 is an alkylene group, R.sup.2 is hydrogen or a C.sub.1 to C.sub.6 alkyl group and x is an integer from 1 to 6, (vi) a C.sub.1 to C.sub.20 monohydric alcohol, (vii) a C.sub.1 to C.sub.20 ketone, (viii) a C.sub.1 to C.sub.10 carboxylic acid ester, or (ix) a C.sub.1 to C.sub.20 ether,component (D) a lubricating oil,component (E) carbon dioxide added subsequent to the, or each, addition of component (B),component (F) a defined carboxylic acid or derivative,component (G) at least one compound which is (i) an inorganic halide or (ii) an ammonium alkanoate or a mono-, di-, tri- or tetra-alkyl ammonium formate or alkanoate provided that when component (G) is (ii), component (F) is not an acid chloride,the weight ratios of all components being such as to produce a concentrate having a TBN greater than 300.

摘要翻译： 一种生产TBN大于300的润滑油添加剂浓缩物的方法，该方法包括在升高的温度下将组分（A）与选自定义的硫化或非硫化酸或其钙盐的限定混合物反应，组分（B） （C）至少一种化合物，其为（i）水，（ii）具有2至4个碳原子的多元醇 ，（iii）二（C3或C4）二醇，（iv）三（C2-C4）二醇，（v）式（I）R（OR1）的单 - 或聚 - 亚烷基二醇烷基醚， xOR 2（I）其中R为C1至C6烷基，R1为亚烷基，R2为氢或C1至C6烷基，x为1至6的整数，（vi）C1至C20一元醇， （vii）C1至C20酮，（viii）C1至C10羧酸酯，或（ix）C1至C20醚，组分（D）润滑油，组分（E）碳二 组分（B），组分（F），所定义的羧酸或衍生物，组分（G），至少一种化合物（i）无机卤化物或（ii）链烷酸铵 或（C）是（ⅱ）组分（F）不是酰基氯，所有组分的重量比例如 产生TBN大于300的浓缩物。

公开(公告)号：US5451331A

公开(公告)日：1995-09-19

申请号：US207222

申请日：1994-03-04

申请人： Sean P. O'Connor ,  John Crawford ,  Charles Cane

发明人： Sean P. O'Connor ,  John Crawford ,  Charles Cane

IPC分类号： C10M159/20 ,  C10M125/00 ,  C10M125/10 ,  C10M125/18 ,  C10M125/20 ,  C10M129/08 ,  C10M129/16 ,  C10M129/38 ,  C10M129/54 ,  C10M129/70 ,  C10M135/30 ,  C10M159/22 ,  C10N10/04 ,  C10N20/02 ,  C10N60/10 ,  C10N70/00

CPC分类号： C10M159/22

摘要： A process for the production of a lubricating oil additive concentrate having a TBN greater than 300 comprises reacting at elevated temperaturecomponent (A) a defined salicylic acid derivative,component (B) an alkaline earth metal base added either in a single addition or in a plurality of additions at internediate points during the reaction,component (C) at least one compound which is (i) water, (ii) a polyhydric alcohol having 2 to 4 carbon atoms, (iii) a di- (C.sub.3 or C.sub.4) glycol, (iv) a tri- (C.sub.2 -C.sub.4) glycol, (iv) a mono- or poly-alkylene glycol alkyl ether of the formula (I)R(OR.sup.1).sub.x OR.sup.2 (I)wherein R is a C.sub.1 to C.sub.6 alkyl group, R.sup.1 is an alkylene group R.sup.2 is hydrogen or a C.sub.1 to C.sub.6 alkyl group and x is an integer from 1 to 6, (vi) a C.sub.1 to C.sub.20 monohydric alcohol, (vii) a C.sub.1 to C.sub.20 ketone, (viii) a C.sub.1 to C.sub.10 carboxylic acid ester, or (ix) a C.sub.1 to C.sub.20 ether,component (D) a lubricating oil,component (E) carbon dioxide added subsequent to the, or each, addition of component (B),component (F) a defined carboxylic acid or derivative, andcomponent (G) at least one compound which is (i) an inorganic halide of (ii) an ammonium alkanoate or mono-, di-, tri- or tetra-alkyl ammonium formate or alkanoate provided that, when component (G) is (ii), component (F) is not an acid chloride,the weight ratios of all components being such as to produce a concentrate having a TBN greater than 300.

摘要翻译： 生产TBN大于300的润滑油添加剂浓缩物的方法包括在升高的温度下使组分（A）与定义的水杨酸衍生物，组分（B）一起添加的碱土金属碱反应， （C）至少一种化合物，其为（i）水，（ii）具有2至4个碳原子的多元醇，（iii）二（C3或C4）二醇 ，（iv）三 - （C 2 -C 4）二醇，（iv）式（I）R（OR 1）x OR 2（I）的单 - 或多 - 亚烷基二醇烷基醚，其中R是C1至C6烷基 R1为亚烷基R2为氢或C1〜C6烷基，x为1〜6的整数，（vi）C1〜C20一元醇，（vii）C1〜C20酮，（viii）C1 至（C）的碳酸酯，或（ix）C1至C20醚，组分（D）润滑油，组分（E）中添加的组分（B），组分（F） ）定义的羧酸或衍生物，和组分（G）至少一种化合物，其是（i）无机卤化物，（ii）烷基铵或烷基甲酸烷基酯或烷酸烷基酯的单，二，三或四烷基铵 当组分（G）为（ⅱ）时，组分（F）不是酰氯，所有组分的重量比都要产生TBN大于300的浓缩物。

公开(公告)号：US5384053A

公开(公告)日：1995-01-24

申请号：US202665

申请日：1994-02-25

申请人： Charles Cane ,  John Crawford ,  Sean P. O'Connor

发明人： Charles Cane ,  John Crawford ,  Sean P. O'Connor

IPC分类号： C10M159/20 ,  C07G99/00 ,  C10M159/24 ,  C10N10/04 ,  C10N20/02 ,  C10N40/25 ,  C10N70/00

CPC分类号： C10M159/24 ,  C07G17/004 ,  C10M2201/082 ,  C10M2203/10 ,  C10M2207/021 ,  C10M2207/022 ,  C10M2207/04 ,  C10M2207/046 ,  C10M2207/08 ,  C10M2207/126 ,  C10M2207/281 ,  C10M2209/108 ,  C10N2210/02 ,  C10N2230/04 ,  C10N2230/06 ,  C10N2230/52 ,  C10N2240/102 ,  C10N2270/02

摘要： A process for the production of a lubricating oil additive concentrate comprises reacting at elevated temperaturecomponent (A) a calcium hydrocarbyl-substituted sulphonate,component (B) an alkaline earth metal base added either in a single addition or in a plurality of additions at intermediate points during the reaction,component (C) at least one compound which is (i) a polyhydric alcohol having 2 to 4 carbon atoms, (ii) a di- (C.sub.3 or C.sub.4) glycol, (iii) a tri- (C.sub.2 -C.sub.4) glycol, (iv) a mono- or poly-alkylene glycol alkyl ether of the formula (I)R(OR.sup.1).sub.x OR.sup.2 (I)wherein R is a C.sub.1 to C.sub.6 alkyl group, R.sup.1 is an alkylene group, R.sup.2 is hydrogen or a C.sub.1 to C.sub.6 alkyl group and x is an integer from 1 to 6, (v) a C.sub.1 to C.sub.20 monohydric alcohol, (vi) a C.sub.1 to C.sub.20 ketone, (vii) a C.sub.1 to C.sub.10 carboxylic acid ester, or (viii) a C.sub.1 to C.sub.20 ether,component (D) a lubricating oil,component (E) carbon dioxide added subsequent to the, or each, addition of component (B),component (F) a defined carboxylic acid or derivative, component (G) at least one compound which is (i) an inorganic halide or (ii) an ammonium alkanoate or a mono-, di-, tri-, or tetra-alkyl ammonium formate or alkanoate provided that, when component (G) is (it), component (F) is not an acid chloride.

摘要翻译： 制备润滑油添加剂浓缩物的方法包括在升高的温度下使组分（A）烃基取代的烃磺酸钙，组分（B）在中间体中以单一添加剂或多种添加剂加入的碱土金属碱 （C）至少一种化合物，其为（i）具有2至4个碳原子的多元醇，（ii）二（C3或C4）二醇，（iii）三 - （C2- C4）二醇，（iv）式（I）R（OR1）xOR2（I）的单 - 或聚 - 亚烷基二醇烷基醚，其中R是C1-C6烷基，R1是亚烷基，R2是氢 或C1〜C6烷基，x为1〜6的整数，（v）C1〜C20一元醇，（vi）C1〜C20酮，（vii）C1〜C10羧酸酯或（viii） ）组分（D），组分（D）润滑油，组分（E）二氧化碳，在组分（B），组分（F）中加入或分别加入一种所定义的羧酸或de （G）至少一种化合物，其为（i）无机卤化物或（ii）烷基铵或单 - ，二 - ，三 - 或四 - 烷基甲酸铵或链烷酸铵，条件是当组分（ G）是（it），组分（F）不是酰氯。

公开(公告)号：US06467680B1

公开(公告)日：2002-10-22

申请号：US09685533

申请日：2000-10-10

申请人： Sean P. O'Connor ,  Eric E. Fitch

发明人： Sean P. O'Connor ,  Eric E. Fitch

IPC分类号： B23K3102

CPC分类号： B23K3/087

摘要： An assembly fixture for optical benches comprises a jig base, having at least one blind hole. The jig base is formed with a surface that is a non-wetting to solder material. The blind hole is shaped and sized in response to dimensions of the optical bench. The fixture further comprises a bench jig shroud. This shroud at least partially covers optical benches installed in the blind holes. Preferably, previsions are made in the top of the jig base at the interface with the jig shroud to facilitate its stable placement on the base.

摘要翻译： 用于光学台的装配夹具包括具有至少一个盲孔的夹具基座。 夹具基底形成有不润湿焊接材料的表面。 盲孔根据光学台的尺寸成形和尺寸。 夹具还包括工作台夹具护罩。 该护罩至少部分地覆盖安装在盲孔中的光学台。 优选地，在与夹具护罩的界面处在夹具基部的顶部进行预制，以便于其稳定地放置在基座上。

公开(公告)号：US5126477A

公开(公告)日：1992-06-30

申请号：US737457

申请日：1991-07-29

申请人： Richard A'Court ,  William J. Fox ,  John E. Hamlin ,  Sean P. O'Connor

发明人： Richard A'Court ,  William J. Fox ,  John E. Hamlin ,  Sean P. O'Connor

IPC分类号： C10L1/224 ,  C10L1/232 ,  C10L1/233

CPC分类号： C10L1/224 ,  C10L1/232 ,  C10L1/2335

摘要： A process for the production of a carbamate suitable for use as a detergent additive to internal combustion engine fuels which process comprises reacting either ammonia, a primary amime or a secondary amine with a dihydrocarbyl carbonate in the presence as catalyst of a strong organic base and in the proportions necessary to produce either a mono-carbamate or a bis-carbamate. A process for the production of a carbamate having formula (I), wherein X and Y are independently either hydrogen, a hydrocarbyl group or a hetero-substituted hydrocarbyl group or the group of formula (II), wherein Z is either a divalent hydrocarbyl, a substituted hydrocarbyl group or the group of formula (III) [alkytene)m(NH)n(alkylene)m] in which n=0 to 4 and m=1 to 4, and R is a hydrocarbly or substituted hydrocarbyl group, provided that if either one of X or Y is the group of formula (II), the other of X or Y is hydrogen, which process comprises reacting a compound of formula (IV), wherein X and Y are independently either hydrogen, a hydrocarbyl group or a hetero-substituted hydrocarbyl group with a dihydrocarbyl carbonate having formula (V), wherein independently R is as defined above in the presence as catalyst of a strong organic base and in the proportions necessary to produce either a mono-carbamate or a bis-carbamate.

摘要翻译： 用于生产适合用作内燃机燃料的洗涤剂添加剂的氨基甲酸酯的方法，该方法包括在作为强有机碱的催化剂存在下，将氨，伯胺或仲胺与碳酸二烃基反应， 生产单氨基甲酸酯或双氨基甲酸酯所需的比例。 制备具有式（I）的氨基甲酸酯的方法，其中X和Y独立地为氢，烃基或杂取代的烃基或式（II）的基团，其中Z为二价烃基， 取代的烃基或式（III）[烷基] m（NH）n（亚烷基）m]的基团，其中n = 0至4且m = 1至4，并且R为烃基或取代的烃基， 如果X或Y中的任一个是式（II）的基团，X或Y中的另一个是氢，该方法包括使式（IV）化合物与其中X和Y独立地是氢，烃基 或具有式（Ⅴ）的二碳代碳酸酯的杂取代烃基，其中独立地R如上所定义，在作为强有机碱的催化剂存在下，以生成单氨基甲酸酯或双 - 氨基甲酸酯。

公开(公告)号：US5075020A

公开(公告)日：1991-12-24

申请号：US667045

申请日：1991-03-11

申请人： Sean P. O'Connor

发明人： Sean P. O'Connor

IPC分类号： C07D237/18 ,  C07D239/58 ,  C07D241/18 ,  C10M135/32 ,  C10N30/06 ,  C10N30/12 ,  C10N40/25

CPC分类号： C10M135/32 ,  C07D237/18 ,  C07D239/58 ,  C07D241/18 ,  C10M2219/09

摘要： Compounds suitable for use as extreme pressure (EP)/anti-wear (AW) agents in lubricating oil compositions, which compounds have the formula:R.sup.1 --S--X--S--S--R (I)whereinR.sup.1 is either R--S-- or hydrogen,R is independently either hydrocarbyl or substituted hydrocarbyl, andX comprises a heterocyclic ring having six atoms of which two are nitrogen atoms.